Computational studies of metal-metal and metal-ligand interactions

NASA Technical Reports Server (NTRS)

Barnes, Leslie A.

1992-01-01

The geometric structure of Cr(CO)6 is optimized at the modified coupled-pair functional (MCPF), single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory (including a perturbational estimate for connected triple excitations), and the force constants for the totally symmetric representation are determined. The geometry of Cr(CO)5 is partially optimized at the MCPF, CCSD and CCSD(T) levels of theory. Comparison with experimental data shows that the CCSD(T) method gives the best results for the structures and force constants, and that remaining errors are probably due to deficiencies in the one-particle basis sets used for CO. A detailed comparison of the properties of free CO is therefore given, at both the MCPF and CCSD/CCSD(T) levels of treatment, using a variety of basis sets. With very large one-particle basis sets, the SSCD(T) method gives excellent results for the bond distance, dipole moment and harmonic frequency of free CO. The total binding energies of Cr(CO)6 and Cr(CO)5 are also determined at the MCPF, CCSD and CCSD(T) levels of theory. The CCSD(T) method gives a much larger total binding energy than either the MCPF or CCSD methods. An analysis of the basis set superposition error (BSSE) at the MCPF level of treatment points out limitations in the one-particle basis used here and in a previous study. Calculations using larger basis sets reduced the BSSE, but the total binding energy of Cr(CO)6 is still significantly smaller than the experimental value, although the first CO bond dissociation energy of Cr(CO)6 is well described. An investigation of 3s3p correlation reveals only a small effect. The remaining discrepancy between the experimental and theoretical total binding energy of Cr(CO)6 is probably due to limitations in the one-particle basis, rather than limitations in the correlation treatment. In particular an additional d function and an f function on each C and O are needed to obtain quantitative results. This is underscored by the fact that even using a very large primitive se (1042 primitive functions contracted to 300 basis functions), the superposition error for the total binding energy of Cr(CO)6 is 22 kcal/mol at the MCPF level of treatment.

Total-energy Assisted Tight-binding Method Based on Local Density Approximation of Density Functional Theory

NASA Astrophysics Data System (ADS)

Fujiwara, Takeo; Nishino, Shinya; Yamamoto, Susumu; Suzuki, Takashi; Ikeda, Minoru; Ohtani, Yasuaki

2018-06-01

A novel tight-binding method is developed, based on the extended Hückel approximation and charge self-consistency, with referring the band structure and the total energy of the local density approximation of the density functional theory. The parameters are so adjusted by computer that the result reproduces the band structure and the total energy, and the algorithm for determining parameters is established. The set of determined parameters is applicable to a variety of crystalline compounds and change of lattice constants, and, in other words, it is transferable. Examples are demonstrated for Si crystals of several crystalline structures varying lattice constants. Since the set of parameters is transferable, the present tight-binding method may be applicable also to molecular dynamics simulations of large-scale systems and long-time dynamical processes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Kyoungsoo, E-mail: kpark16@illinois.ed; Paulino, Glaucio H.; Roesler, Jeffery

A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. Inmore » addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.« less

Variational formulation and stability analysis of a three dimensional superelastic model for shape memory alloys

NASA Astrophysics Data System (ADS)

Alessi, Roberto; Pham, Kim

2016-02-01

This paper presents a variational framework for the three-dimensional macroscopic modelling of superelastic shape memory alloys in an isothermal setting. Phase transformation is accounted through a unique second order tensorial internal variable, acting as the transformation strain. Postulating the total strain energy density as the sum of a free energy and a dissipated energy, the model depends on two material scalar functions of the norm of the transformation strain and a material scalar constant. Appropriate calibration of these material functions allows to render a wide range of constitutive behaviours including stress-softening and stress-hardening. The quasi-static evolution problem of a domain is formulated in terms of two physical principles based on the total energy of the system: a stability criterion, which selects the local minima of the total energy, and an energy balance condition, which ensures the consistency of the evolution of the total energy with respect to the external loadings. The local phase transformation laws in terms of Kuhn-Tucker relations are deduced from the first-order stability condition and the energy balance condition. The response of the model is illustrated with a numerical traction-torsion test performed on a thin-walled cylinder. Evolutions of homogeneous states are given for proportional and non-proportional loadings. Influence of the stress-hardening/softening properties on the evolution of the transformation domain is emphasized. Finally, in view of an identification process, the issue of stability of homogeneous states in a multi-dimensional setting is answered based on the study of second-order derivative of the total energy. Explicit necessary and sufficient conditions of stability are provided.

Correlation energy functional within the GW -RPA: Exact forms, approximate forms, and challenges

NASA Astrophysics Data System (ADS)

Ismail-Beigi, Sohrab

2010-05-01

In principle, the Luttinger-Ward Green’s-function formalism allows one to compute simultaneously the total energy and the quasiparticle band structure of a many-body electronic system from first principles. We present approximate and exact expressions for the correlation energy within the GW -random-phase approximation that are more amenable to computation and allow for developing efficient approximations to the self-energy operator and correlation energy. The exact form is a sum over differences between plasmon and interband energies. The approximate forms are based on summing over screened interband transitions. We also demonstrate that blind extremization of such functionals leads to unphysical results: imposing physical constraints on the allowed solutions (Green’s functions) is necessary. Finally, we present some relevant numerical results for atomic systems.

DFTB3: Extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB).

PubMed

Gaus, Michael; Cui, Qiang; Elstner, Marcus

2012-04-10

The self-consistent-charge density-functional tight-binding method (SCC-DFTB) is an approximate quantum chemical method derived from density functional theory (DFT) based on a second-order expansion of the DFT total energy around a reference density. In the present study we combine earlier extensions and improve them consistently with, first, an improved Coulomb interaction between atomic partial charges, and second, the complete third-order expansion of the DFT total energy. These modifications lead us to the next generation of the DFTB methodology called DFTB3, which substantially improves the description of charged systems containing elements C, H, N, O, and P, especially regarding hydrogen binding energies and proton affinities. As a result, DFTB3 is particularly applicable to biomolecular systems. Remaining challenges and possible solutions are also briefly discussed.

Kinetic Energy of Hydrocarbons as a Function of Electron Density and Convolutional Neural Networks.

PubMed

Yao, Kun; Parkhill, John

2016-03-08

We demonstrate a convolutional neural network trained to reproduce the Kohn-Sham kinetic energy of hydrocarbons from an input electron density. The output of the network is used as a nonlocal correction to conventional local and semilocal kinetic functionals. We show that this approximation qualitatively reproduces Kohn-Sham potential energy surfaces when used with conventional exchange correlation functionals. The density which minimizes the total energy given by the functional is examined in detail. We identify several avenues to improve on this exploratory work, by reducing numerical noise and changing the structure of our functional. Finally we examine the features in the density learned by the neural network to anticipate the prospects of generalizing these models.

Accurate Energies and Orbital Description in Semi-Local Kohn-Sham DFT

NASA Astrophysics Data System (ADS)

Lindmaa, Alexander; Kuemmel, Stephan; Armiento, Rickard

2015-03-01

We present our progress on a scheme in semi-local Kohn-Sham density-functional theory (KS-DFT) for improving the orbital description while still retaining the level of accuracy of the usual semi-local exchange-correlation (xc) functionals. DFT is a widely used tool for first-principles calculations of properties of materials. A given task normally requires a balance of accuracy and computational cost, which is well achieved with semi-local DFT. However, commonly used semi-local xc functionals have important shortcomings which often can be attributed to features of the corresponding xc potential. One shortcoming is an overly delocalized representation of localized orbitals. Recently a semi-local GGA-type xc functional was constructed to address these issues, however, it has the trade-off of lower accuracy of the total energy. We discuss the source of this error in terms of a surplus energy contribution in the functional that needs to be accounted for, and offer a remedy for this issue which formally stays within KS-DFT, and, which does not harshly increase the computational effort. The end result is a scheme that combines accurate total energies (e.g., relaxed geometries) with an improved orbital description (e.g., improved band structure).

Thermodynamics of the living organisms. Allometric relationship between the total metabolic energy, chemical energy and body temperature in mammals

NASA Astrophysics Data System (ADS)

Atanasov, Atanas Todorov

2017-11-01

The study present relationship between the total metabolic energy (ETME(c), J) derived as a function of body chemical energy (Gchem, J) and absolute temperature (Tb, K) in mammals: ETME(c) =Gchem (Tb/Tn). In formula the temperature Tn =2.73K appears normalization temperature. The calculated total metabolic energy ETME(c) differs negligible from the total metabolic energy ETME(J), received as a product between the basal metabolic rate (Pm, J/s) and the lifespan (Tls, s) of mammals: ETME = Pm×Tls. The physical nature and biological mean of the normalization temperature (Tn, K) is unclear. It is made the hypothesis that the kTn energy (where k= 1.3806×10-23 J/K -Boltzmann constant) presents energy of excitation states (modes) in biomolecules and body structures that could be in equilibrium with chemical energy accumulated in body. This means that the accumulated chemical energy allows trough all body molecules and structures to propagate excitations states with kTn energy with wavelength in the rage of width of biological membranes. The accumulated in biomolecules chemical energy maintains spread of the excited states through biomolecules without loss of energy.

Analysis of the total kinetic energy of fission fragments with the Langevin equation

NASA Astrophysics Data System (ADS)

Usang, M. D.; Ivanyuk, F. A.; Ishizuka, C.; Chiba, S.

2017-12-01

We analyzed the total kinetic energy (TKE) of fission fragments with three-dimensional Langevin calculations for a series of actinides and Fm isotopes at various excitation energies. This allowed us to establish systematic trends of TKE with Z2/A1 /3 of the fissioning system and as a function of excitation energy. In the mass-energy distributions of fission fragments we see the contributions from the standard, super-long, and super-short (in the case of 258Fm) fission modes. For the fission fragments mass distribution of 258Fm we obtained a single peak mass distribution. The decomposition of TKE into the prescission kinetic energy and Coulomb repulsion showed that decrease of TKE with growing excitation energy is accompanied by a decrease of prescission kinetic energy. It was also found that transport coefficients (friction and inertia tensors) calculated by a microscopic model and by macroscopic models give drastically different behaviors of TKE as a function of excitation energy. The results obtained with microscopic transport coefficients are much closer to experimental data than those calculated with macroscopic ones.

Modeling of clover detector in addback mode

NASA Astrophysics Data System (ADS)

Kshetri, R.

2012-07-01

Based on absorption and scattering of gamma-rays, a formalism has been presented for modeling the clover germanium detector in addback mode and to predict its response for high energy γ-rays. In the present formalism, the operation of a bare clover detector could be described in terms of three quantities only. Considering an additional parameter, the formalism could be extended for suppressed clover. Using experimental data on relative single crystal efficiency and addback factor as input, the peak-to-total ratio has been calculated for three energies (Eγ = 3.401, 5.324 and 10.430 MeV) where direct measurement of peak-to-total ratio is impossible due to absence of a radioactive source having single monoenergetic gamma-ray of that energy. The experimental validation and consistency of the formalism have been shown considering data for TIGRESS clover detector. In a recent work (R. Kshetri, JINST 2012 7 P04008), we showed that for a given γ-ray energy, the formalism could be used to predict the peak-to-total ratio as a function of number of detector modules. In the present paper, we have shown that for a given composite detector (clover detector is considered here), the formalism could be used to predict the peak-to-total ratio as a function of γ-ray energy.

Erosion and deuterium retention of CLF-1 steel exposed to deuterium plasma

NASA Astrophysics Data System (ADS)

Qiao, L.; Wang, P.; Hu, M.; Gao, L.; Jacob, W.; Fu, E. G.; Luo, G. N.

2017-12-01

In recent years reduced activation ferritic martensitic steel has been proposed as the plasma-facing material in remote regions of the first wall. This study reports the erosion and deuterium retention behaviours in CLF-1 steel exposed to deuterium (D) plasma in a linear experimental plasma system as function of incident ion energy and fluence. The incident D ion energy ranges from 30 to 180 eV at a flux of 4 × 1021 D m-2 s-1 up to a fluence of 1025 D m-2. SEM images revealed a clear change of the surface morphology as functions of incident fluence and impinging energy. The mass loss results showed a decrease of the total sputtering yield of CLF-1 steel with increasing incident fluence by up to one order of magnitude. The total sputtering yield of CLF-1 steel after 7.2 × 1024 D m-2 deuterium plasma exposure reduced by a factor of 4 compared with that of pure iron, which can be attributed to the enrichment of W at the surface due to preferential sputtering of iron and chromium. After D plasma exposure, the total deuterium retention in CLF-1 steel samples measured by TDS decreased with increasing incident fluence and energy, and a clear saturation tendency as function of incident fluence or energy was also observed.

Measurements of the inclusive neutrino and antineutrino charged current cross sections in MINERvA using the low-ν flux method

NASA Astrophysics Data System (ADS)

Devan, J.; Ren, L.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Budd, H.; Cai, T.; Carneiro, M. F.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Endress, E.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Gallagher, H.; Ghosh, A.; Gran, R.; Harris, D. A.; Higuera, A.; Hurtado, K.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman, Paolone, V.; Park, J.; Patrick, C. E.; Perdue, G. N.; Ramirez, M. A.; Ransome, R. D.; Ray, H.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tice, B. G.; Valencia, E.; Wolcott, J.; Wospakrik, M.; Minerva Collaboration

2016-12-01

The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an in situ prediction of the shape of the flux as a function of neutrino energy from 2-50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy (ν ) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-ν flux technique, the first time it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeV energies. The cross section measurements presented are the most precise measurements to date below 5 GeV.

Measurements of the inclusive neutrino and antineutrino charged current cross sections in MINERvA using the low- ν flux method

DOE PAGES

Devan, J.

2016-12-20

The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an in situ prediction of the shape of the flux as a function of neutrino energy from 2–50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy (ν) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-ν flux technique, the first timemore » it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeV energies. Lastly, the cross section measurements presented are the most precise measurements to date below 5 GeV.« less

Tuning electronic properties in graphene quantum dots by chemical functionalization: Density functional theory calculations

NASA Astrophysics Data System (ADS)

Abdelsalam, Hazem; Elhaes, Hanan; Ibrahim, Medhat A.

2018-03-01

The energy gap and dipole moment of chemically functionalized graphene quantum dots are investigated by density functional theory. The energy gap can be tuned through edge passivation by different elements or groups. Edge passivation by oxygen considerably decreases the energy gap in hexagonal nanodots. Edge states in triangular quantum dots can also be manipulated by passivation with fluorine. The dipole moment depends on: (a) shape and edge termination of the quantum dot, (b) attached group, and (c) position to which the groups are attached. Depending on the position of attached groups, the total dipole can be increased, decreased, or eliminated.

NASA B737 flight test results of the Total Energy Control System

NASA Technical Reports Server (NTRS)

Bruce, K. R.; Kelly, J. R.; Person, L. H., Jr.

1986-01-01

The Total Energy Control System was developed and tested in September 1985 during five flights on the NASA Langley Transport System Research Vehicle, a modified Boeing B737. In the system, the total kinetic and potential energy of the aircraft is controlled by the throttles, and the energy distribution is controlled by the elevator. A common inner loop is used for each mode of the autopilot, and all the control functions of a conventional pitch autopilot and autothrottle are integrated into a single generalized control concept, providing decoupled flightpath and maneuver control, and a coordinated throttle response for all maneuvers. No instabilities or design problems requiring gain adjustment in flight were found, and comparison with simulation results showed excellent path tracking.

Spectroscopic analysis of transition state energy levels - Bending-rotational spectrum and lifetime analysis of H3 quasibound states

NASA Technical Reports Server (NTRS)

Zhao, Meishan; Mladenovic, Mirjana; Truhlar, Donald G.; Schwenke, David W.; Sharafeddin, Omar

1989-01-01

Converged quantum mechanical calculations of scattering matrices and transition probabilities are reported for the reaction of H with H2 with total angular momentum 0, 1, and 4 as functions of total energy in the range 0.85-1.15 eV on an accurate potential energy surface. The resonance structure is illustrated with Argand diagrams. State-to-state reactive collision delay times and lifetimes are presented. For J = 0, 1, and 4, the lowest-energy H3 resonance is at total energies of 0.983, 0.985, and 1.01 eV, respectively, with lifetimes of about 16-17 fs. For J = 1 and 4 there is a higher-energy resonance at 1.10-1.11 eV. For J = 1 the lifetime is about 4 fs and for J = 4 it is about 1 fs.

Derivative discontinuity and exchange-correlation potential of meta-GGAs in density-functional theory.

PubMed

Eich, F G; Hellgren, Maria

2014-12-14

We investigate fundamental properties of meta-generalized-gradient approximations (meta-GGAs) to the exchange-correlation energy functional, which have an implicit density dependence via the Kohn-Sham kinetic-energy density. To this purpose, we construct the most simple meta-GGA by expressing the local exchange-correlation energy per particle as a function of a fictitious density, which is obtained by inverting the Thomas-Fermi kinetic-energy functional. This simple functional considerably improves the total energy of atoms as compared to the standard local density approximation. The corresponding exchange-correlation potentials are then determined exactly through a solution of the optimized effective potential equation. These potentials support an additional bound state and exhibit a derivative discontinuity at integer particle numbers. We further demonstrate that through the kinetic-energy density any meta-GGA incorporates a derivative discontinuity. However, we also find that for commonly used meta-GGAs the discontinuity is largely underestimated and in some cases even negative.

Derivative discontinuity and exchange-correlation potential of meta-GGAs in density-functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eich, F. G., E-mail: eichf@missouri.edu; Hellgren, Maria

2014-12-14

We investigate fundamental properties of meta-generalized-gradient approximations (meta-GGAs) to the exchange-correlation energy functional, which have an implicit density dependence via the Kohn-Sham kinetic-energy density. To this purpose, we construct the most simple meta-GGA by expressing the local exchange-correlation energy per particle as a function of a fictitious density, which is obtained by inverting the Thomas-Fermi kinetic-energy functional. This simple functional considerably improves the total energy of atoms as compared to the standard local density approximation. The corresponding exchange-correlation potentials are then determined exactly through a solution of the optimized effective potential equation. These potentials support an additional bound state andmore » exhibit a derivative discontinuity at integer particle numbers. We further demonstrate that through the kinetic-energy density any meta-GGA incorporates a derivative discontinuity. However, we also find that for commonly used meta-GGAs the discontinuity is largely underestimated and in some cases even negative.« less

Atomic electron energies including relativistic effects and quantum electrodynamic corrections

NASA Technical Reports Server (NTRS)

Aoyagi, M.; Chen, M. H.; Crasemann, B.; Huang, K. N.; Mark, H.

1977-01-01

Atomic electron energies have been calculated relativistically. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first order correction to the local approximation was thus included. Quantum-electrodynamic corrections were made. For all orbitals in all atoms with 2 less than or equal to Z less than or equal to 106, the following quantities are listed: total energies, electron kinetic energies, electron-nucleus potential energies, electron-electron potential energies consisting of electrostatic and Breit interaction (magnetic and retardation) terms, and vacuum polarization energies. These results will serve for detailed comparison of calculations based on other approaches. The magnitude of quantum electrodynamic corrections is exhibited quantitatively for each state.

Angular distributions for H- formation in single collisions of H+ on Mg

NASA Astrophysics Data System (ADS)

Alvarez, I.; Cisneros, C.; Russek, A.

1982-07-01

Absolute differential cross sections have been measured for H- formation in single collisions of H+ on Mg in the energy range from 0.5 to 5.0 keV. Total cross sections, obtained by direct integration of these differential cross sections, are in good agreement with earlier total-cross-section measurements of Morgan and Eriksen in the energy range common to the two experiments and are in good agreement with the calculated total cross sections of Olson and Liu. The differential cross sections are strongly peaked in the forward direction. The functional form and scaling properties of this forward peak strongly indicate that it is a glory maximum, which occurs when the classical deflection function changes over from attractive to repulsive at some finite impact parameter. The differential cross sections from 1.0 to 5.0 keV show no other structure, but below 1.0 keV a τ-dependent structure is observed which becomes more pronounced as the collision energy decreases. 1982 The American Physical Society.

NASA B737 flight test results of the total energy control system

NASA Technical Reports Server (NTRS)

Bruce, Kevin R.

1987-01-01

The Total Energy Control System (TECS) is an integrated autopilot/autothrottle developed by BCAC that was test flown on NASA Langley's Transport System Research Vehicle (i.e., a highly modified Boeing B737). This systems was developed using principles of total energy in which the total kinetic and potential energy of the airplane was controlled by the throttles, and the energy distribution controled by the elevator. TECS integrates all the control functions of a conventional pitch autopilot and autothrottle into a single generalized control concept. This integration provides decoupled flightpath and maneuver control, as well as a coordinated throttle response for all maneuvers. A mode hierarchy was established to preclude exceeding airplane safety and performance limits. The flight test of TECS took place as a series of five flights over a 33-week period during September 1985 at NASA Langley. Most of the original flight test plan was completed within the first three flights with the system not exhibiting any instabilities or design problems that required any gain adjustment during flight.

The effects of a high-animal- and a high-vegetable-protein diet on mineral balance and bowel function of young men.

PubMed

Van Dokkum, W; Wesstra, A; Luyken, R; Hermus, R J

1986-09-01

1. Twelve young men were given for periods of 20 d, each of three mixed diets, namely a low-protein (LP) diet (9% total energy as protein, 67% of animal origin), a high-animal-protein (HA) diet (16% total energy as protein, 67% of animal origin) and a high-vegetable-protein (HV) diet (16% total energy as protein, 67% of vegetable origin). Retention of calcium, magnesium, iron, zinc and copper as well as various bowel function indices were investigated during each dietary period. 2. Neither the HA diet nor the HV diet changed the retention of the minerals considerably. Only Fe balance decreased significantly on the HV diet. 3. Substituting the HV diet for the HA diet resulted in significant increases in faecal wet weight (17 g/d), defaecation frequency (0.12 stools/d), faecal volatile fatty acids (2.6 mmol/d) and a decrease in faecal bile acids (128 mumol/d). 4. It is concluded that a HV diet, rather than a HA diet is to be recommended with respect to bowel function, whereas the HV diet does not necessarily have a significant influence on mineral retention.

FAMBE-pH: A Fast and Accurate Method to Compute the Total Solvation Free Energies of Proteins

PubMed Central

Vorobjev, Yury N.; Vila, Jorge A.

2009-01-01

A fast and accurate method to compute the total solvation free energies of proteins as a function of pH is presented. The method makes use of a combination of approaches, some of which have already appeared in the literature; (i) the Poisson equation is solved with an optimized fast adaptive multigrid boundary element (FAMBE) method; (ii) the electrostatic free energies of the ionizable sites are calculated for their neutral and charged states by using a detailed model of atomic charges; (iii) a set of optimal atomic radii is used to define a precise dielectric surface interface; (iv) a multilevel adaptive tessellation of this dielectric surface interface is achieved by using multisized boundary elements; and (v) 1:1 salt effects are included. The equilibrium proton binding/release is calculated with the Tanford–Schellman integral if the proteins contain more than ∼20–25 ionizable groups; for a smaller number of ionizable groups, the ionization partition function is calculated directly. The FAMBE method is tested as a function of pH (FAMBE-pH) with three proteins, namely, bovine pancreatic trypsin inhibitor (BPTI), hen egg white lysozyme (HEWL), and bovine pancreatic ribonuclease A (RNaseA). The results are (a) the FAMBE-pH method reproduces the observed pKa's of the ionizable groups of these proteins within an average absolute value of 0.4 pK units and a maximum error of 1.2 pK units and (b) comparison of the calculated total pH-dependent solvation free energy for BPTI, between the exact calculation of the ionization partition function and the Tanford–Schellman integral method, shows agreement within 1.2 kcal/mol. These results indicate that calculation of total solvation free energies with the FAMBE-pH method can provide an accurate prediction of protein conformational stability at a given fixed pH and, if coupled with molecular mechanics or molecular dynamics methods, can also be used for more realistic studies of protein folding, unfolding, and dynamics, as a function of pH. PMID:18683966

A density functional for core-valence correlation energy

NASA Astrophysics Data System (ADS)

Ranasinghe, Duminda S.; Frisch, Michael J.; Petersson, George A.

2015-12-01

A density functional, ɛCV-DFT(ρc, ρv), describing the core-valence correlation energy has been constructed as a linear combination of ɛLY Pcorr(ρc), ɛV WN5corr(ρc, ρv), ɛPBEcorr(ρc, ρv), ɛSlaterex(ρc, ρv), ɛHCTHex(ρc, ρv), ɛHFex(ρc, ρv), and F CV -DFT (" separators=" N i , Z i ) , a function of the nuclear charges. This functional, with 6 adjustable parameters, reproduces (±0.27 kcal/mol rms error) a benchmark set of 194 chemical energy changes including 9 electron affinities, 18 ionization potentials, and 167 total atomization energies covering the first- and second-rows of the periodic table. This is almost twice the rms error (±0.16 kcal/mol) obtained with CCSD(T)/MTsmall calculations, but less than half the rms error (±0.65 kcal/mol) obtained with MP2/GTlargeXP calculations, and somewhat smaller than the rms error (±0.39 kcal/mol) obtained with CCSD/MTsmall calculations. The largest positive and negative errors from ɛCV-DFT(ρc, ρv) were 0.88 and -0.75 kcal/mol with the set of 194 core-valence energy changes ranging from +3.76 kcal/mol for the total atomization energy of propyne to -9.05 kcal/mol for the double ionization of Mg. Evaluation of the ɛCV-DFT(ρc, ρv) functional requires less time than a single SCF iteration, and the accuracy is adequate for any model chemistry based on the CCSD(T) level of theory.

Theoretical L-shell Coster-Kronig energies 11 or equal to z or equal to 103

NASA Technical Reports Server (NTRS)

Chen, M. H.; Crasemann, B.; Huang, K. N.; Aoyagi, M.; Mark, H.

1976-01-01

Relativistic relaxed-orbital calculations of L-shell Coster-Kronig transition energies have been performed for all possible transitions in atoms with atomic numbers. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first-order approximation to the local approximation was thus included. Quantum-electrodynamic corrections were made. Each transition energy was computed as the difference between results of separate self-consistent-field calculations for the initial, singly ionized state and the final two-hole state. The following quantities are listed: total transition energy, 'electric' (Dirac-Hartree-Fock-Slater) contribution, magnetic and retardation contributions, and contributions due to vacuum polarization and self energy.

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Schlereth, J.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Frasconi, F.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Geitz, G.; Grothe, M.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mass, A.; Mengel, S.; Mollen, J.; Paul, E.; Rembser, Ch.; Schattevoy, R.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. J.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Böttcher, S.; Coldewey, C.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Göttlicher, P.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Hultschig, H.; Iga, Y.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Kröger, W.; Krüger, J.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mańczak, O.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; De Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Schroeder, J.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, I.; Jamieson, V. A.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Fürtjes, A.; Hagge, L.; Lohrmann, E.; Mainusch, J.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Terron, J.; Zetsche, F.; Bacon, T. C.; Beuselinck, R.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Zhang, Y.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; del Peso, J.; Puga, J.; de Trocóniz, J. F.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Laurent, M. St.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kobrin, V. D.; Kuzmin, V. A.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Bentvelsen, S.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Jong, P.; de Kamps, M.; Kooijman, P.; Kruse, A.; O'Dell, V.; Tenner, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Daniels, D.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Luffman, P. E.; Lindemann, L.; McFall, J.; Nath, C.; Quadt, A.; Uijterwaal, H.; Walczak, R.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Iori, M.; Marini, G.; Mattioli, M.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Dubbs, T.; Heusch, C.; Van Hook, M.; Hubbard, B.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Biltzinger, J.; Seifert, R. J.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nagira, T.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Crombie, M. B.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Kochocki, J.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchuła, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Revel, D.; Shapira, A.; Ali, I.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Tsurugai, T.; Bhadra, S.; Frisken, W. R.; Furutani, K. M.; ZEUS Collaboration

1995-02-01

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the γp centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.

Competition between surface chemisorption and cage formation in Fe12O12 clusters

NASA Astrophysics Data System (ADS)

Gutsev, G. L.; Weatherford, C. A.; Jena, P.; Johnson, E.; Ramachandran, B. R.

2013-01-01

The electronic and geometrical structures of the clusters composed of 12 iron and 12 oxygen atoms are obtained using all-electron density functional theory. It is found that the states with geometrical structures corresponding to oxygen chemisorbed on the ground-state Fe12 cluster surface (Fe12O12) are close in total energy to the states whose geometrical configurations are hollow cages (FeO)12. The lowest total energy state is the ferrimagnetic triplet state of Fe12O12. A ferrimagnetic nonet state of (FeO)12 is only marginally higher in total energy. The clusters are rich in nearly degenerate isomers. Oxygen adsorption dramatically quenches the spin of Fe12 clusters.

Microhartree precision in density functional theory calculations

NASA Astrophysics Data System (ADS)

Gulans, Andris; Kozhevnikov, Anton; Draxl, Claudia

2018-04-01

To address ultimate precision in density functional theory calculations we employ the full-potential linearized augmented plane-wave + local-orbital (LAPW + lo) method and justify its usage as a benchmark method. LAPW + lo and two completely unrelated numerical approaches, the multiresolution analysis (MRA) and the linear combination of atomic orbitals, yield total energies of atoms with mean deviations of 0.9 and 0.2 μ Ha , respectively. Spectacular agreement with the MRA is reached also for total and atomization energies of the G2-1 set consisting of 55 molecules. With the example of α iron we demonstrate the capability of LAPW + lo to reach μ Ha /atom precision also for periodic systems, which allows also for the distinction between the numerical precision and the accuracy of a given functional.

Temperature and energy effects on secondary electron emission from SiC ceramics induced by Xe17+ ions.

PubMed

Zeng, Lixia; Zhou, Xianming; Cheng, Rui; Wang, Xing; Ren, Jieru; Lei, Yu; Ma, Lidong; Zhao, Yongtao; Zhang, Xiaoan; Xu, Zhongfeng

2017-07-25

Secondary electron emission yield from the surface of SiC ceramics induced by Xe 17+ ions has been measured as a function of target temperature and incident energy. In the temperature range of 463-659 K, the total yield gradually decreases with increasing target temperature. The decrease is about 57% for 3.2 MeV Xe 17+ impact, and about 62% for 4.0 MeV Xe 17+ impact, which is much larger than the decrease observed previously for ion impact at low charged states. The yield dependence on the temperature is discussed in terms of work function, because both kinetic electron emission and potential electron emission are influenced by work function. In addition, our experimental data show that the total electron yield gradually increases with the kinetic energy of projectile, when the target is at a constant temperature higher than room temperature. This result can be explained by electronic stopping power which plays an important role in kinetic electron emission.

Active Space Dependence in Multiconfiguration Pair-Density Functional Theory.

PubMed

Sharma, Prachi; Truhlar, Donald G; Gagliardi, Laura

2018-02-13

In multiconfiguration pair-density functional theory (MC-PDFT), multiconfiguration self-consistent-field calculations and on-top density functionals are combined to describe both static and dynamic correlation. Here, we investigate how the MC-PDFT total energy and its components depend on the active space choice in the case of the H 2 and N 2 molecules. The active space dependence of the on-top pair density, the total density, the ratio of on-top pair density to half the square of the electron density, and the satisfaction of the virial theorem are also explored. We find that the density and on-top pair density do not change significantly with changes in the active space. However, the on-top ratio does change significantly with respect to active space change, and this affects the on-top energy. This study provides a foundation for designing on-top density functionals and automatizing the active space choice in MC-PDFT.

Dynamic biomechanical examination of the lumbar spine with implanted total spinal segment replacement (TSSR) utilizing a pendulum testing system.

PubMed

Daniels, Alan H; Paller, David J; Koruprolu, Sarath; Palumbo, Mark A; Crisco, Joseph J

2013-01-01

Biomechanical investigations of spinal motion preserving implants help in the understanding of their in vivo behavior. In this study, we hypothesized that the lumbar spine with implanted total spinal segment replacement (TSSR) would exhibit decreased dynamic stiffness and more rapid energy absorption compared to native functional spinal units under simulated physiologic motion when tested with the pendulum system. Five unembalmed, frozen human lumbar functional spinal units were tested on the pendulum system with axial compressive loads of 181 N, 282 N, 385 N, and 488 N before and after Flexuspine total spinal segment replacement implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5°; resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and bending stiffness (N-m/°) was calculated and compared for each testing mode. The total spinal segment replacement reached equilibrium with significantly fewer cycles to equilibrium compared to the intact functional spinal unit at all loads in flexion (p<0.011), and at loads of 385 N and 488 N in lateral bending (p<0.020). Mean bending stiffness in flexion, extension, and lateral bending increased with increasing load for both the intact functional spinal unit and total spinal segment replacement constructs (p<0.001), with no significant differences in stiffness between the intact functional spinal unit and total spinal segment replacement in any of the test modes (p>0.18). Lumbar functional spinal units with implanted total spinal segment replacement were found to have similar dynamic bending stiffness, but absorbed energy at a more rapid rate than intact functional spinal units during cyclic loading with an unconstrained pendulum system. Although the effects on clinical performance of motion preserving devices is not fully known, these results provide further insight into the biomechanical behavior of this device under approximated physiologic loading conditions.

Dynamic Biomechanical Examination of the Lumbar Spine with Implanted Total Spinal Segment Replacement (TSSR) Utilizing a Pendulum Testing System

PubMed Central

Daniels, Alan H.; Paller, David J.; Koruprolu, Sarath; Palumbo, Mark A.; Crisco, Joseph J.

2013-01-01

Background Biomechanical investigations of spinal motion preserving implants help in the understanding of their in vivo behavior. In this study, we hypothesized that the lumbar spine with implanted total spinal segment replacement (TSSR) would exhibit decreased dynamic stiffness and more rapid energy absorption compared to native functional spinal units under simulated physiologic motion when tested with the pendulum system. Methods Five unembalmed, frozen human lumbar functional spinal units were tested on the pendulum system with axial compressive loads of 181 N, 282 N, 385 N, and 488 N before and after Flexuspine total spinal segment replacement implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5°; resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and bending stiffness (N-m/°) was calculated and compared for each testing mode. Results The total spinal segment replacement reached equilibrium with significantly fewer cycles to equilibrium compared to the intact functional spinal unit at all loads in flexion (p<0.011), and at loads of 385 N and 488 N in lateral bending (p<0.020). Mean bending stiffness in flexion, extension, and lateral bending increased with increasing load for both the intact functional spinal unit and total spinal segment replacement constructs (p<0.001), with no significant differences in stiffness between the intact functional spinal unit and total spinal segment replacement in any of the test modes (p>0.18). Conclusions Lumbar functional spinal units with implanted total spinal segment replacement were found to have similar dynamic bending stiffness, but absorbed energy at a more rapid rate than intact functional spinal units during cyclic loading with an unconstrained pendulum system. Although the effects on clinical performance of motion preserving devices is not fully known, these results provide further insight into the biomechanical behavior of this device under approximated physiologic loading conditions. PMID:23451222

Evidence that multiple genetic variants of MC4R play a functional role in the regulation of energy expenditure and appetite in Hispanic children1234

PubMed Central

Cole, Shelley A; Voruganti, V Saroja; Cai, Guowen; Haack, Karin; Kent, Jack W; Blangero, John; Comuzzie, Anthony G; McPherson, John D; Gibbs, Richard A

2010-01-01

Background: Melanocortin-4-receptor (MC4R) haploinsufficiency is the most common form of monogenic obesity; however, the frequency of MC4R variants and their functional effects in general populations remain uncertain. Objective: The aim was to identify and characterize the effects of MC4R variants in Hispanic children. Design: MC4R was resequenced in 376 parents, and the identified single nucleotide polymorphisms (SNPs) were genotyped in 613 parents and 1016 children from the Viva la Familia cohort. Measured genotype analysis (MGA) tested associations between SNPs and phenotypes. Bayesian quantitative trait nucleotide (BQTN) analysis was used to infer the most likely functional polymorphisms influencing obesity-related traits. Results: Seven rare SNPs in coding and 18 SNPs in flanking regions of MC4R were identified. MGA showed suggestive associations between MC4R variants and body size, adiposity, glucose, insulin, leptin, ghrelin, energy expenditure, physical activity, and food intake. BQTN analysis identified SNP 1704 in a predicted micro-RNA target sequence in the downstream flanking region of MC4R as a strong, probable functional variant influencing total, sedentary, and moderate activities with posterior probabilities of 1.0. SNP 2132 was identified as a variant with a high probability (1.0) of exerting a functional effect on total energy expenditure and sleeping metabolic rate. SNP rs34114122 was selected as having likely functional effects on the appetite hormone ghrelin, with a posterior probability of 0.81. Conclusion: This comprehensive investigation provides strong evidence that MC4R genetic variants are likely to play a functional role in the regulation of weight, not only through energy intake but through energy expenditure. PMID:19889825

Neutral-atom electron binding energies from relaxed-orbital relativistic Hartree-Fock-Slater calculations for Z between 2 and 106

NASA Technical Reports Server (NTRS)

Huang, K.-N.; Aoyagi, M.; Mark, H.; Chen, M. H.; Crasemann, B.

1976-01-01

Electron binding energies in neutral atoms have been calculated relativistically, with the requirement of complete relaxation. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first-order correction to the local approximation was thus included. Quantum-electrodynamic corrections were made. For all elements with atomic numbers ranging from 2 to 106, the following quantities are listed: total energies, electron kinetic energies, electron-nucleus potential energies, electron-electron potential energies consisting of electrostatic and Breit interaction (magnetic and retardation) terms, and vacuum polarization energies. Binding energies including relaxation are listed for all electrons in all atoms over the indicated range of atomic numbers. A self-energy correction is included for the 1s, 2s, and 2p(1/2) levels. Results for selected atoms are compared with energies calculated by other methods and with experimental values.

Final excitation energy of fission fragments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, Karl-Heinz; Jurado, Beatriz

We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission, where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition in statistical equilibrium for different level-density descriptions as a function of the total intrinsic excitation energy of themore » fissioning system. Excitation energies are found to be strongly enhanced in the heavy fragment, if the level density follows a constant-temperature behavior at low energies, e.g., in the composed Gilbert-Cameron description.« less

Density functional theory calculations of the water interactions with ZrO2 nanoparticles Y2O3 doped

NASA Astrophysics Data System (ADS)

Subhoni, Mekhrdod; Kholmurodov, Kholmirzo; Doroshkevich, Aleksandr; Asgerov, Elmar; Yamamoto, Tomoyuki; Lyubchyk, Andrei; Almasan, Valer; Madadzada, Afag

2018-03-01

Development of a new electricity generation techniques is one of the most relevant tasks, especially nowadays under conditions of extreme growth in energy consumption. The exothermic heterogeneous electrochemical energy conversion to the electric energy through interaction of the ZrO2 based nanopowder system with atmospheric moisture is one of the ways of electric energy obtaining. The questions of conversion into the electric form of the energy of water molecules adsorption in 3 mol% Y2O3 doped ZrO2 nanopowder systems were investigated using the density functional theory calculations. The density functional theory calculations has been realized as in the Kohn-Sham formulation, where the exchange-correlation potential is approximated by a functional of the electronic density. The electronic density, total energy and band structure calculations are carried out using the all-electron, full potential, linear augmented plane wave method of the electronic density and related approximations, i.e. the local density, the generalized gradient and their hybrid approximations.

The derivative discontinuity of the exchange-correlation functional.

PubMed

Mori-Sánchez, Paula; Cohen, Aron J

2014-07-28

The derivative discontinuity is a key concept in electronic structure theory in general and density functional theory in particular. The electronic energy of a quantum system exhibits derivative discontinuities with respect to different degrees of freedom that are a consequence of the integer nature of electrons. The classical understanding refers to the derivative discontinuity of the total energy as a function of the total number of electrons (N), but it can also manifest at constant N. Examples are shown in models including several hydrogen systems with varying numbers of electrons or nuclear charge (Z), as well as the 1-dimensional Hubbard model (1DHM). Two sides of the problem are investigated: first, the failure of currently used approximate exchange-correlation functionals in DFT and, second, the importance of the derivative discontinuity in the exact electronic structure of molecules, as revealed by full configuration interaction (FCI). Currently, all approximate functionals, including hybrids, miss the derivative discontinuity, leading to basic errors that can be seen in many ways: from the complete failure to give the total energy of H2 and H2(+), to the missing gap in Mott insulators such as stretched H2 and the thermodynamic limit of the 1DHM, or a qualitatively incorrect density in the HZ molecule with two electrons and incorrect electron transfer processes. Description of the exact particle behaviour of electrons is emphasised, which is key to many important physical processes in real systems, especially those involving electron transfer, and offers a challenge for the development of new exchange-correlation functionals.

Landscape of an exact energy functional

NASA Astrophysics Data System (ADS)

Cohen, Aron J.; Mori-Sánchez, Paula

2016-04-01

One of the great challenges of electronic structure theory is the quest for the exact functional of density functional theory. Its existence is proven, but it is a complicated multivariable functional that is almost impossible to conceptualize. In this paper the asymmetric two-site Hubbard model is studied, which has a two-dimensional universe of density matrices. The exact functional becomes a simple function of two variables whose three-dimensional energy landscape can be visualized and explored. A walk on this unique landscape, tilted to an angle defined by the one-electron Hamiltonian, gives a valley whose minimum is the exact total energy. This is contrasted with the landscape of some approximate functionals, explaining their failure for electron transfer in the strongly correlated limit. We show concrete examples of pure-state density matrices that are not v representable due to the underlying nonconvex nature of the energy landscape. The exact functional is calculated for all numbers of electrons, including fractional, allowing the derivative discontinuity to be visualized and understood. The fundamental gap for all possible systems is obtained solely from the derivatives of the exact functional.

Shear-strain gradient induced polarization reversal in ferroelectric BaTiO3 thin films: A first-principles total-energy study

NASA Astrophysics Data System (ADS)

Li, Guannan; Huang, Xiaokun; Hu, Jingsan; Zhang, Weiyi

2017-04-01

Based on the first-principles total-energy calculation, we have studied the shear-strain gradient effect on the polarization reversal of ferroelectric BaTiO3 thin films. By calculating the energies of double-domain supercells for different electric polarization, shear-strain gradients, and domain-wall displacement, we extracted, in addition to the domain-wall energy, the polarization energy, elastic energy, and flexoelectric coefficient of a single domain. The constructed Landau-Devonshire phenomenological theory yields a critical shear-strain gradient of 9.091 ×107/m (or a curvature radius (R ) of 110 Å) for reversing the 180∘ domain at room temperature, which is on the same order of the experimentally estimated value of 3.333 ×107/m (R =300 Å ). In contrast to the commonly used linear response theory, the flexoelectric coefficient derived from fitting the total energy to a Landau-Devonshire energy functional does not depend on the specific pseudopotential. Thus, our method offers an alternative numerical approach to study the flexoelectric effect.

Effect of carbon-composite knee-ankle-foot orthoses on walking efficiency and gait in former polio patients.

PubMed

Brehm, Merel-Anne; Beelen, Anita; Doorenbosch, Caroline A M; Harlaar, Jaap; Nollet, Frans

2007-10-01

To investigate the effects of total-contact fitted carbon-composite knee-ankle-foot orthoses (KAFOs) on energy cost of walking in patients with former polio who normally wear a conventional leather/metal KAFO or plastic/metal KAFO. A prospective uncontrolled study with a multiple baseline and follow-up design. Follow-up measurements continued until 26 weeks after intervention. Twenty adults with polio residuals (mean age 55 years). Each participant received a new carbon-composite KAFO, fitted according to a total-contact principle, which resulted in a rigid, lightweight and well-fitting KAFO. Energy cost of walking, walking speed, biomechanics of gait, physical functioning and patient satisfaction. The energy cost decreased significantly, by 8%, compared with the original KAFO. Furthermore, the incremention energy cost during walking with the carbon-composite KAFO was reduced by 18% towards normative values. An improvement in knee flexion, forward excursion of the centre of pressure, peak ankle moment, and timing of peak ankle power were significantly associated with the decrease in energy cost. Walking speed and physical functioning remained unchanged. In patients with former polio, carbon-composite KAFOs are superior to conventional leather/metal and plastic/metal KAFOs with respect to improving walking efficiency and gait, and are therefore important in reducing overuse and maintaining functional abilities in polio survivors.

From The Cover: The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties.

PubMed

Xu, Xin; Goddard, William A

2004-03-02

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee-Yang-Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energies [over the most popular and accurate method, B3LYP (Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional)]. X3LYP also leads to a good description of dipole moments, polarizabilities, and accurate excitation energies from s to d orbitals for transition metal atoms and ions. We suggest that X3LYP will be useful for predicting ligand binding in proteins and DNA.

From The Cover: The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties

NASA Astrophysics Data System (ADS)

Xu, Xin; Goddard, William A., III

2004-03-01

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee-Yang-Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energies [over the most popular and accurate method, B3LYP (Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional)]. X3LYP also leads to a good description of dipole moments, polarizabilities, and accurate excitation energies from s to d orbitals for transition metal atoms and ions. We suggest that X3LYP will be useful for predicting ligand binding in proteins and DNA.

The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties

PubMed Central

Xu, Xin; Goddard, William A.

2004-01-01

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee–Yang–Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energies [over the most popular and accurate method, B3LYP (Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional)]. X3LYP also leads to a good description of dipole moments, polarizabilities, and accurate excitation energies from s to d orbitals for transition metal atoms and ions. We suggest that X3LYP will be useful for predicting ligand binding in proteins and DNA. PMID:14981235

Low-energy ion distribution functions on a magnetically quiet day at geostationary altitude /L = 7/

NASA Technical Reports Server (NTRS)

Singh, N.; Raitt, W. J.; Yasuhara, F.

1982-01-01

Ion energy and pitch angle distribution functions are examined for a magnetically quiet day using averaged data from ATS 6. For both field-aligned and perpendicular fluxes, the populations have a mixture of characteristic energies, and the distribution functions can be fairly well approximated by Maxwellian distributions over three different energy bands in the range 3-600 eV. Pitch angle distributions varying with local time, and energy distributions are used to compute total ion density. Pitch angle scattering mechanisms responsible for the observed transformation of pitch angle distribution are examined, and it is found that a magnetic noise of a certain power spectral density belonging to the electromagnetic ion cyclotron mode near the ion cyclotron frequency can be effective in trapping the field aligned fluxes by pitch angle scattering.

Ground-state energies of simple metals

NASA Technical Reports Server (NTRS)

Hammerberg, J.; Ashcroft, N. W.

1974-01-01

A structural expansion for the static ground-state energy of a simple metal is derived. Two methods are presented, one an approach based on single-particle band structure which treats the electron gas as a nonlinear dielectric, the other a more general many-particle analysis using finite-temperature perturbation theory. The two methods are compared, and it is shown in detail how band-structure effects, Fermi-surface distortions, and chemical-potential shifts affect the total energy. These are of special interest in corrections to the total energy beyond third order in the electron-ion interaction and hence to systems where differences in energies for various crystal structures are exceptionally small. Preliminary calculations using these methods for the zero-temperature thermodynamic functions of atomic hydrogen are reported.

Structural expansions for the ground state energy of a simple metal

NASA Technical Reports Server (NTRS)

Hammerberg, J.; Ashcroft, N. W.

1973-01-01

A structural expansion for the static ground state energy of a simple metal is derived. An approach based on single particle band structure which treats the electron gas as a non-linear dielectric is presented, along with a more general many particle analysis using finite temperature perturbation theory. The two methods are compared, and it is shown in detail how band-structure effects, Fermi surface distortions, and chemical potential shifts affect the total energy. These are of special interest in corrections to the total energy beyond third order in the electron ion interaction, and hence to systems where differences in energies for various crystal structures are exceptionally small. Preliminary calculations using these methods for the zero temperature thermodynamic functions of atomic hydrogen are reported.

Low-energy fusion dynamics of weakly bound nuclei: A time dependent perspective

NASA Astrophysics Data System (ADS)

Diaz-Torres, A.; Boselli, M.

2016-05-01

Recent dynamical fusion models for weakly bound nuclei at low incident energies, based on a time-dependent perspective, are briefly presented. The main features of both the PLATYPUS model and a new quantum approach are highlighted. In contrast to existing timedependent quantum models, the present quantum approach separates the complete and incomplete fusion from the total fusion. Calculations performed within a toy model for 6Li + 209Bi at near-barrier energies show that converged excitation functions for total, complete and incomplete fusion can be determined with the time-dependent wavepacket dynamics.

The IRAS radiation environment

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.

1978-01-01

Orbital flux integration for three selected mission altitudes and geographic instantaneous flux-mapping for nominal flight-path altitude were used to determine the external charged particle radiation predicted for the Infrared Astronomy Satellite. A current field model was used for magnetic field definitions for three nominal circular trajectories and for the geographic mapping positions. Innovative analysis features introduced include (1) positional fluxes as a function of time and energy for the most severe pass through the South Atlantic Anomaly; (2) total positional doses as a function of time and shield thickness; (3) comparison mapping fluxes for ratios of positional intensities to orbit integrated averages; and (4) statistical exposure-time history of a trajectory as a function of energy indicating, in percent of total mission duration, the time intervals over which the instantaneous fluxes would exceed the orbit integrated averages. Results are presented in tables and graphs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Sunniva J.; Zeiser, Fabio; Wilson, J. N.

Prompt-fission γ rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modeling nuclear reactors. In this work we present prompt γ-ray emission characteristics in fission as a function of the nuclear excitation energy of the fissioning system. Emitted γ-ray spectra were measured, and γ-ray multiplicities and average and total γ energies per fission were determined for the 233U(d,pf) reaction for excitation energies between 4.8 and 10 MeV, and for the 239Pu(d,pf) reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energymore » above the fission barrier, despite the fact that an extra ~5 MeV of energy is potentially available in the excited fragments for γ decay. The measured results are compared with model calculations made for prompt γ-ray emission with the fission model code gef. In conclusion, further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate (d,p) reaction.« less

Factor demand in Swedish manufacturing industry with special reference to the demand for energy. Instantaneous adjustment models; some results

NASA Astrophysics Data System (ADS)

Sjoeholm, K. R.

1981-02-01

The dual approach to the theory of production is used to estimate factor demand functions of the Swedish manufacturing industry. Two approximations of the cost function, the translog and the generalized Leontief models, are used. The price elasticities of the factor demand do not seem to depend on the choice of model. This is at least true as to the sign pattern and as to the inputs capital, labor, total energy and other materials. Total energy is separated into solid fuels, gasoline, fuel oil, electricity and a residual. Fuel oil and electricity are found to be substitutes by both models. Capital and energy are shown to be substitutes. This implies that Swedish industry will save more energy if the capital cost can be reduced. Both models are, in the best versions, able to detect an inappropriate variable. The assumption of perfect competition on the product market, is shown to be inadequate by both models. When this assumption is relaxed, the normal substitution pattern among the inputs is resumed.

Time-dependent density-functional tight-binding method with the third-order expansion of electron density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimoto, Yoshio, E-mail: nishimoto.yoshio@fukui.kyoto-u.ac.jp

2015-09-07

We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of themore » third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.« less

Time-dependent density-functional tight-binding method with the third-order expansion of electron density.

PubMed

Nishimoto, Yoshio

2015-09-07

We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of the third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.

Investigation of the electronic, magnetic and optical properties of newest carbon allotrope

NASA Astrophysics Data System (ADS)

Kazemi, Samira; Moradian, Rostam

2018-05-01

We investigate triple properties of monolayer pentagon graphene that include electronic, magnetic and optical properties based on density functional theory (DFT). Our results show that in the electronic and magnetic properties this structure with a direct energy gap of about 2.2 eV along Γ - Γ direction and total magnetic moment of 0.0013 μB per unit cell is almost a non-magnetic semiconductor. Also, its optical properties show that if this allotrope used in solar cell technology, its efficiency in the low energy will be better, because, in the range of energy, its loss energy function and reflectivity will be minimum.

Density-functional theory for internal magnetic fields

NASA Astrophysics Data System (ADS)

Tellgren, Erik I.

2018-01-01

A density-functional theory is developed based on the Maxwell-Schrödinger equation with an internal magnetic field in addition to the external electromagnetic potentials. The basic variables of this theory are the electron density and the total magnetic field, which can equivalently be represented as a physical current density. Hence, the theory can be regarded as a physical current density-functional theory and an alternative to the paramagnetic current density-functional theory due to Vignale and Rasolt. The energy functional has strong enough convexity properties to allow a formulation that generalizes Lieb's convex analysis formulation of standard density-functional theory. Several variational principles as well as a Hohenberg-Kohn-like mapping between potentials and ground-state densities follow from the underlying convex structure. Moreover, the energy functional can be regarded as the result of a standard approximation technique (Moreau-Yosida regularization) applied to the conventional Schrödinger ground-state energy, which imposes limits on the maximum curvature of the energy (with respect to the magnetic field) and enables construction of a (Fréchet) differentiable universal density functional.

Industry Efficiency and Total Factor Productivity Growth under Resources and Environmental Constraint in China

PubMed Central

Tao, Feng; Li, Ling; Xia, X. H.

2012-01-01

The growth of China's industry has been seriously depending on energy and environment. This paper attempts to apply the directional distance function and the Luenberger productivity index to measure the environmental efficiency, environmental total factor productivity, and its components at the level of subindustry in China over the period from 1999 to 2009 while considering energy consumption and emission of pollutants. This paper also empirically examines the determinants of efficiency and productivity change. The major findings are as follows. Firstly, the main sources of environmental inefficiency of China's industry are the inefficiency of gross industrial output value, the excessive energy consumption, and pollutant emissions. Secondly, the highest growth rate of environmental total factor productivity among the three industrial categories is manufacturing, followed by mining, and production and supply of electricity, gas, and water. Thirdly, foreign direct investment, capital-labor ratio, ownership structure, energy consumption structure, and environmental regulation have varying degrees of effects on the environmental efficiency and environmental total factor productivity. PMID:23365517

Industry efficiency and total factor productivity growth under resources and environmental constraint in China.

PubMed

Tao, Feng; Li, Ling; Xia, X H

2012-01-01

The growth of China's industry has been seriously depending on energy and environment. This paper attempts to apply the directional distance function and the Luenberger productivity index to measure the environmental efficiency, environmental total factor productivity, and its components at the level of subindustry in China over the period from 1999 to 2009 while considering energy consumption and emission of pollutants. This paper also empirically examines the determinants of efficiency and productivity change. The major findings are as follows. Firstly, the main sources of environmental inefficiency of China's industry are the inefficiency of gross industrial output value, the excessive energy consumption, and pollutant emissions. Secondly, the highest growth rate of environmental total factor productivity among the three industrial categories is manufacturing, followed by mining, and production and supply of electricity, gas, and water. Thirdly, foreign direct investment, capital-labor ratio, ownership structure, energy consumption structure, and environmental regulation have varying degrees of effects on the environmental efficiency and environmental total factor productivity.

Locv Calculations for Polarized Liquid 3He with the Spin-Dependent Correlation

NASA Astrophysics Data System (ADS)

Bordbar, G. H.; Karimi, M. J.

We have used the lowest order constrained variational (LOCV) method to calculate some ground-state properties of polarized liquid 3 He at zero temperature with the spin-dependent correlation function employing the Lennard-Jones and Aziz pair potentials. We have seen that the total energy of polarized liquid 3He increases with increasing polarization. For all polarizations, it is shown that the total energy in the spin-dependent case is lower than the spin-independent case. We have seen that the difference between the energies of spin-dependent and spin-independent cases decreases by increasing the polarization. We have shown that the main contribution of the potential energy comes from the spin-triplet state.

Ground-state energies and highest occupied eigenvalues of atoms in exchange-only density-functional theory

NASA Astrophysics Data System (ADS)

Li, Yan; Harbola, Manoj K.; Krieger, J. B.; Sahni, Viraht

1989-11-01

The exchange-correlation potential of the Kohn-Sham density-functional theory has recently been interpreted as the work required to move an electron against the electric field of its Fermi-Coulomb hole charge distribution. In this paper we present self-consistent results for ground-state total energies and highest occupied eigenvalues of closed subshell atoms as obtained by this formalism in the exchange-only approximation. The total energies, which are an upper bound, lie within 50 ppm of Hartree-Fock theory for atoms heavier than Be. The highest occupied eigenvalues, as a consequence of this interpretation, approximate well the experimental ionization potentials. In addition, the self-consistently calculated exchange potentials are very close to those of Talman and co-workers [J. D. Talman and W. F. Shadwick, Phys. Rev. A 14, 36 (1976); K. Aashamar, T. M. Luke, and J. D. Talman, At. Data Nucl. Data Tables 22, 443 (1978)].

Mass-number and excitation-energy dependence of the spin cutoff parameter

DOE PAGES

Grimes, S. M.; Voinov, A. V.; Massey, T. N.

2016-07-12

Here, the spin cutoff parameter determining the nuclear level density spin distribution ρ(J) is defined through the spin projection as < J 2 z > 1/2 or equivalently for spherical nuclei, (< J(J+1) >/3) 1/2. It is needed to divide the total level density into levels as a function of J. To obtain the total level density at the neutron binding energy from the s-wave resonance count, the spin cutoff parameter is also needed. The spin cutoff parameter has been calculated as a function of excitation energy and mass with a super-conducting Hamiltonian. Calculations have been compared with two commonlymore » used semiempirical formulas. A need for further measurements is also observed. Some complications for deformed nuclei are discussed. The quality of spin cut off parameter data derived from isomeric ratio measurement is examined.« less

Solid-solution aqueous-solution equilibria: thermodynamic theory and representation

USGS Publications Warehouse

Glynn, P.D.; Reardon, E.J.

1990-01-01

Thorstenson and Plummer's (1977) "stoichiometric saturation' model is reviewed, and a general relation between stoichiometric saturation Kss constants and excess free energies of mixing is derived for a binary solid-solution B1-xCxA: GE = RT[ln Kss - xln(xKCA) - (l-x)ln((l-x)KBA)]. This equation allows a suitable excess free energy function, such as Guggenheim's (1937) sub-regular function, to be fitted from experimentally determined Kss constants. Solid-phase free energies and component activity-coefficients can then be determined from one or two fitted parameters and from the endmember solubility products KBA and KCA. A general form of Lippmann's (1977,1980) "solutus equation is derived from an examination of Lippmann's (1977,1980) "total solubility product' model. Lippmann's ??II or "total solubility product' variable is used to represent graphically not only thermodynamic equilibrium states and primary saturation states but also stoichiometric saturation and pure phase saturation states. -from Authors

MITHRAS: A Program of Simultaneous Radar Observations of the High-Latitude Auroral Zone.

DTIC Science & Technology

1982-11-01

Latitude * and Time for Chatanika ..... ................. ... 38 111-5 Cross Polar Cap Potential Versus Solar-Wind Energy Parameter...49 vii 9 III-10 Scatter Plot of Pedersen Conductivities as a Function of Average Energy for Two Levels of Total...Precipitated Energy ....... ....... ......... .. 51 -IIl-1 For Initial Time and Steady State, (a) Latitudinal Profile of the Meridional Electric-Field

Energy dependence of the prompt γ -ray emission from the ( d , p ) -induced fission of U * 234 and Pu * 240

DOE PAGES

Rose, Sunniva J.; Zeiser, Fabio; Wilson, J. N.; ...

2017-07-05

Prompt-fission γ rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modeling nuclear reactors. In this work we present prompt γ-ray emission characteristics in fission as a function of the nuclear excitation energy of the fissioning system. Emitted γ-ray spectra were measured, and γ-ray multiplicities and average and total γ energies per fission were determined for the 233U(d,pf) reaction for excitation energies between 4.8 and 10 MeV, and for the 239Pu(d,pf) reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energymore » above the fission barrier, despite the fact that an extra ~5 MeV of energy is potentially available in the excited fragments for γ decay. The measured results are compared with model calculations made for prompt γ-ray emission with the fission model code gef. In conclusion, further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate (d,p) reaction.« less

Orthogonality of embedded wave functions for different states in frozen-density embedding theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zech, Alexander; Wesolowski, Tomasz A.; Aquilante, Francesco

2015-10-28

Other than lowest-energy stationary embedded wave functions obtained in Frozen-Density Embedding Theory (FDET) [T. A. Wesolowski, Phys. Rev. A 77, 012504 (2008)] can be associated with electronic excited states but they can be mutually non-orthogonal. Although this does not violate any physical principles — embedded wave functions are only auxiliary objects used to obtain stationary densities — working with orthogonal functions has many practical advantages. In the present work, we show numerically that excitation energies obtained using conventional FDET calculations (allowing for non-orthogonality) can be obtained using embedded wave functions which are strictly orthogonal. The used method preserves the mathematicalmore » structure of FDET and self-consistency between energy, embedded wave function, and the embedding potential (they are connected through the Euler-Lagrange equations). The orthogonality is built-in through the linearization in the embedded density of the relevant components of the total energy functional. Moreover, we show formally that the differences between the expectation values of the embedded Hamiltonian are equal to the excitation energies, which is the exact result within linearized FDET. Linearized FDET is shown to be a robust approximation for a large class of reference densities.« less

Ultraviolet optical absorptions of semiconducting copper phosphate glasses

NASA Technical Reports Server (NTRS)

Bae, Byeong-Soo; Weinberg, Michael C.

1993-01-01

Results are presented of a quantitative investigation of the change in UV optical absorption in semiconducting copper phosphate glasses with batch compositions of 40, 50, and 55 percent CuO, as a function of the Cu(2+)/Cu(total) ratio in the glasses for each glass composition. It was found that optical energy gap, E(opt), of copper phosphate glass is a function of both glass composition and Cu(2+)/Cu(total) ratio in the glass. E(opt) increases as the CuO content for fixed Cu(2+)/Cu(total) ratio and the Cu(2+)/Cu(total) ratio for fixed glass composition are reduced.

Energy and energy gradient matrix elements with N-particle explicitly correlated complex Gaussian basis functions with L =1

NASA Astrophysics Data System (ADS)

Bubin, Sergiy; Adamowicz, Ludwik

2008-03-01

In this work we consider explicitly correlated complex Gaussian basis functions for expanding the wave function of an N-particle system with the L =1 total orbital angular momentum. We derive analytical expressions for various matrix elements with these basis functions including the overlap, kinetic energy, and potential energy (Coulomb interaction) matrix elements, as well as matrix elements of other quantities. The derivatives of the overlap, kinetic, and potential energy integrals with respect to the Gaussian exponential parameters are also derived and used to calculate the energy gradient. All the derivations are performed using the formalism of the matrix differential calculus that facilitates a way of expressing the integrals in an elegant matrix form, which is convenient for the theoretical analysis and the computer implementation. The new method is tested in calculations of two systems: the lowest P state of the beryllium atom and the bound P state of the positronium molecule (with the negative parity). Both calculations yielded new, lowest-to-date, variational upper bounds, while the number of basis functions used was significantly smaller than in previous studies. It was possible to accomplish this due to the use of the analytic energy gradient in the minimization of the variational energy.

Energy and energy gradient matrix elements with N-particle explicitly correlated complex Gaussian basis functions with L=1.

PubMed

Bubin, Sergiy; Adamowicz, Ludwik

2008-03-21

In this work we consider explicitly correlated complex Gaussian basis functions for expanding the wave function of an N-particle system with the L=1 total orbital angular momentum. We derive analytical expressions for various matrix elements with these basis functions including the overlap, kinetic energy, and potential energy (Coulomb interaction) matrix elements, as well as matrix elements of other quantities. The derivatives of the overlap, kinetic, and potential energy integrals with respect to the Gaussian exponential parameters are also derived and used to calculate the energy gradient. All the derivations are performed using the formalism of the matrix differential calculus that facilitates a way of expressing the integrals in an elegant matrix form, which is convenient for the theoretical analysis and the computer implementation. The new method is tested in calculations of two systems: the lowest P state of the beryllium atom and the bound P state of the positronium molecule (with the negative parity). Both calculations yielded new, lowest-to-date, variational upper bounds, while the number of basis functions used was significantly smaller than in previous studies. It was possible to accomplish this due to the use of the analytic energy gradient in the minimization of the variational energy.

Effects of intraduodenal infusion of L-tryptophan on ad libitum eating, antropyloroduodenal motility, glycemia, insulinemia, and gut peptide secretion in healthy men.

PubMed

Steinert, Robert E; Luscombe-Marsh, Natalie D; Little, Tanya J; Standfield, Scott; Otto, Bärbel; Horowitz, Michael; Feinle-Bisset, Christine

2014-09-01

Changes in gut motor and hormonal function contribute to the eating-inhibitory and glucose-lowering effects of protein. The effect of amino acids, the digestive products of protein, on gastrointestinal function, eating, and glycemia has not been investigated comprehensively. We tested the hypothesis that L-tryptophan (L-Trp) stimulates gastrointestinal motor and hormonal functions, inhibits eating, and modulates glycemia. Design, Settings, Participants, and Intervention: Ten healthy, normal-weight men were studied in randomized, double-blind fashion, each receiving a 90-minute intraduodenal infusion of L-Trp at 0.075 (total 6.75 kcal) or 0.15 (total 13.5 kcal) kcal/min or saline (control). Antropyloroduodenal motility, plasma ghrelin, cholecystokinin, glucagon-like peptide-1, peptide tyrosine tyrosine, insulin, glucagon, blood glucose, and appetite perceptions were measured. Food intake was quantified from a buffet meal after the infusion. Intraduodenal L-Trp suppressed antral pressures (P < .05) and stimulated pyloric pressures (P < .01) and markedly increased cholecystokinin and glucagon (both P < .001). Glucagon-like peptide-1 and peptide tyrosine tyrosine increased modestly (both P < .001), but there was no effect on total ghrelin. Insulin increased slightly (P < .05) without affecting blood glucose. Plasma L-Trp increased substantially (P < .001). All effects were dose-related and associated with increased fullness and substantially decreased energy intake (P < .001). There was a strong inverse correlation between energy intake and plasma L-Trp (r = -0.70; P < .001). Low caloric intraduodenal loads of L-Trp affect gut motor and hormonal function and markedly reduce energy intake. A strong inverse correlation between energy intake and plasma L-Trp suggests that, beyond gut mechanisms, direct effects of circulating L-Trp mediate its eating-inhibitory effect.

Semi-local machine-learned kinetic energy density functional with third-order gradients of electron density

NASA Astrophysics Data System (ADS)

Seino, Junji; Kageyama, Ryo; Fujinami, Mikito; Ikabata, Yasuhiro; Nakai, Hiromi

2018-06-01

A semi-local kinetic energy density functional (KEDF) was constructed based on machine learning (ML). The present scheme adopts electron densities and their gradients up to third-order as the explanatory variables for ML and the Kohn-Sham (KS) kinetic energy density as the response variable in atoms and molecules. Numerical assessments of the present scheme were performed in atomic and molecular systems, including first- and second-period elements. The results of 37 conventional KEDFs with explicit formulae were also compared with those of the ML KEDF with an implicit formula. The inclusion of the higher order gradients reduces the deviation of the total kinetic energies from the KS calculations in a stepwise manner. Furthermore, our scheme with the third-order gradient resulted in the closest kinetic energies to the KS calculations out of the presented functionals.

Molecular Mechanics: The Method and Its Underlying Philosophy.

ERIC Educational Resources Information Center

Boyd, Donald B.; Lipkowitz, Kenny B.

1982-01-01

Molecular mechanics is a nonquantum mechanical method for solving problems concerning molecular geometries and energy. Methodology based on: the principle of combining potential energy functions of all structural features of a particular molecule into a total force field; derivation of basic equations; and use of available computer programs is…

Band structures in coupled-cluster singles-and-doubles Green's function (GFCCSD)

NASA Astrophysics Data System (ADS)

Furukawa, Yoritaka; Kosugi, Taichi; Nishi, Hirofumi; Matsushita, Yu-ichiro

2018-05-01

We demonstrate that the coupled-cluster singles-and-doubles Green's function (GFCCSD) method is a powerful and prominent tool drawing the electronic band structures and the total energies, which many theoretical techniques struggle to reproduce. We have calculated single-electron energy spectra via the GFCCSD method for various kinds of systems, ranging from ionic to covalent and van der Waals, for the first time: the one-dimensional LiH chain, one-dimensional C chain, and one-dimensional Be chain. We have found that the bandgap becomes narrower than in HF due to the correlation effect. We also show that the band structures obtained from the GFCCSD method include both quasiparticle and satellite peaks successfully. Besides, taking one-dimensional LiH as an example, we discuss the validity of restricting the active space to suppress the computational cost of the GFCCSD method. We show that the calculated results without bands that do not contribute to the chemical bonds are in good agreement with full-band calculations. With the GFCCSD method, we can calculate the total energies and spectral functions for periodic systems in an explicitly correlated manner.

Vibrational analysis and quantum chemical calculations of 2,2‧-bipyridine Zinc(II) halide complexes

NASA Astrophysics Data System (ADS)

Ozel, Aysen E.; Kecel, Serda; Akyuz, Sevim

2007-05-01

In this study the molecular structure and vibrational spectra of Zn(2,2'-bipyridine)X 2 (X = Cl and Br) complexes were studied in their ground states by computational vibrational study and scaled quantum mechanical (SQM) analysis. The geometry optimization, vibrational wavenumber and intensity calculations of free and coordinated 2,2'-bipyridine were carried out with the Gaussian03 program package by using Hartree-Fock (HF) and Density Functional Theory (DFT) with B3LYP functional and 6-31G (d,p) basis set. The total energy distributions (TED) of the vibrational modes were calculated by using Scaled Quantum Mechanical (SQM) analysis. Fundamentals were characterised by their total energy distributions. Coordination sensitive modes of 2,2'-bipyridine were determined.

Total energy based flight control system

NASA Technical Reports Server (NTRS)

Lambregts, Antonius A. (Inventor)

1985-01-01

An integrated aircraft longitudinal flight control system uses a generalized thrust and elevator command computation (38), which accepts flight path angle, longitudinal acceleration command signals, along with associated feedback signals, to form energy rate error (20) and energy rate distribution error (18) signals. The engine thrust command is developed (22) as a function of the energy rate distribution error and the elevator position command is developed (26) as a function of the energy distribution error. For any vertical flight path and speed mode the outerloop errors are normalized (30, 34) to produce flight path angle and longitudinal acceleration commands. The system provides decoupled flight path and speed control for all control modes previously provided by the longitudinal autopilot, autothrottle and flight management systems.

Generalized Jastrow variational method for liquid3He-4He mixtures at T=0 K

NASA Astrophysics Data System (ADS)

Mirabbaszadeh, K.

1989-07-01

The ground state energy of a dilute solution of mass-3 fermions in liquid4He is analyzed by a variational procedure based on the Jastrow many body theory. The antisymmetry of the wave function for fermions is incorporated following the procedure given by Lado, Inguva, and Smith. A set of coupled integrodifferential equations is solved in the hypernetted chain approximation yielding expressions for the binding energy of3He-4He mixtures; the radial distribution function is given together with the total energy for various values of density and the interparticle separation r s.

Study of component technologies for fuel cell on-site integrated energy system. Volume 2: Appendices

NASA Technical Reports Server (NTRS)

Lee, W. D.; Mathias, S.

1980-01-01

This data base catalogue was compiled in order to facilitate the analysis of various on site integrated energy system with fuel cell power plants. The catalogue is divided into two sections. The first characterizes individual components in terms of their performance profiles as a function of design parameters. The second characterizes total heating and cooling systems in terms of energy output as a function of input and control variables. The integrated fuel cell systems diagrams and the computer analysis of systems are included as well as the cash flows series for baseline systems.

An all-electron density functional theory study of the structure and properties of the neutral and singly charged M12 and M13 clusters: M = Sc-Zn.

PubMed

Gutsev, G L; Weatherford, C W; Belay, K G; Ramachandran, B R; Jena, P

2013-04-28

The electronic and geometrical structures of the M12 and M13 clusters where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn along with their singly negatively and positively charged ions are studied using all-electron density functional theory within the generalized gradient approximation. The geometries corresponding to the lowest total energy states of singly and negatively charged ions of V13, Mn12, Co12, Ni13, Cu13, Zn12, and Zn13 are found to be different from the geometries of the corresponding neutral parents. The computed ionization energies of the neutrals, vertical electron detachment energies from the anions, and energies required to remove a single atom from the M13 and M13(+) clusters are in good agreement with experiment. The change in a total spin magnetic moment of the cation or anion with respect to a total spin magnetic moment of the corresponding neutral is consistent with the one-electron model in most cases, i.e., they differ by ±1.0 μ(B). Exceptions are found only for Sc12(-), Ti12(+), Mn12(-), Mn12(+), Fe12(-), Fe13(+), and Co12(+).

Complex Correlation Kohn-T Method of Calculating Total and Elastic Cross Sections. Part 1; Electron-Hydrogen Elastic Scattering

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We report on the first part of a study of electron-hydrogen scattering, using a method which allows for the ab initio calculation of total and elastic cross sections at higher energies. In its general form the method uses complex 'radial' correlation functions, in a (Kohn) T-matrix formalism. The titled method, abbreviated Complex Correlation Kohn T (CCKT) method, is reviewed, in the context of electron-hydrogen scattering, including the derivation of the equation for the (complex) scattering function, and the extraction of the scattering information from the latter. The calculation reported here is restricted to S-waves in the elastic region, where the correlation functions can be taken, without loss of generality, to be real. Phase shifts are calculated using Hylleraas-type correlation functions with up to 95 terms. Results are rigorous lower bounds; they are in general agreement with those of Schwartz, but they are more accurate and outside his error bounds at a couple of energies,

Toward a Unified View of Black-Hole High-Energy States

NASA Technical Reports Server (NTRS)

Nowak, Michael A.

1995-01-01

We present here a review of high-energy (greater than 1 keV) observations of seven black-hole candidates, six of which have estimated masses. In this review we focus on two parameters of interest: the ratio of 'nonthermal' to total luminosity as a function of the total luminosity divided by the Eddington luminosity, and the root-mean-square (rms) variability as a function of the nonthermal-to-total luminosity ratio. Below approx. 10% Eddington luminosity, the sources tend to be strictly nonthermal (the so called 'off' and 'low' states). Above this luminosity the sources become mostly thermal (the 'high' state). with the nonthermal component increasing with luminosity (the 'very high' and 'flare' states). There are important exceptions to this behavior, however, and no steady - as opposed to transient - source has been observed over a wide range of parameter space. In addition, the rms variability is positively correlated with the ratio of nonthermal to total luminosity, although there may be a minimum level of variability associated with 'thermal' states. We discuss these results in light of theoretical models and find that currently no single model describes the full range of black-hole high-energy behavior. In fact, the observations are exactly opposite from what one expects based upon simple notions of accretion disk instabilities.

Energy Management Policies in Distributed Residential Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Sisi; Sun, Jingtao

2016-01-01

In this paper, we study energy management problems in communities with several neighborhood-level Residential Energy Systems (RESs). We consider control problems from both community level and residential level to handle external changes such as restriction on peak demand and restriction on the total demand from the electricity grid. We propose three policies to handle the problems at community level. Based on the collected data from RESs such as predicted energy load, the community controller analyzes the policies, distribute the results to the RES, and each RES can then control and schedule its own energy load based on different coordination functions.more » We utilize a framework to integrate both policy analysis and coordination of functions. With the use of our approach, we show that the policies are useful to resolve the challenges of energy management under external changes.« less

Preliminary analysis of the Jimo coastal ecosystem with the ecopath model

NASA Astrophysics Data System (ADS)

Su, Meng

2016-12-01

The Jimo coast encompasses an area of 2157 km2, and the ecosystem is valuable both socially and economically with regional fisheries substantially contributing to the value. A mass-balanced trophic model consisting of 15 functional ecological groups was developed for the coastal ecosystem using the Ecopath model in Ecopath with Ecosim (EwE) software (version 6.4.3). The results of the model simulations indicated that the trophic levels of the functional groups varied between 1.0 and 3.76, and the total production of the system was estimated to be 5112.733 t km-2 yr-1 with a total energy transfer efficiency of 17.6%. The proportion of the total flow originating from detritus was estimated to be 48%, whereas that from primary producers was 52%, indicating that the grazing food chain dominated the energy flow. The ratio of total primary productivity to total respiration in the system was 3.78, and the connectivity index was 0.4. The fin cycling index and the mean path length of the energy flow were 4.92% and 2.57%, respectively, which indicated that the ecosystem exhibits relatively low maturity and stability. The mixed trophic impact (MTI) procedure suggested that the ecological groups at lower trophic levels dominated the feeding dynamics in the Jimo coastal ecosystem. Overfishing is thought to be the primary reason for the degeneration of the Jimo coastal ecosystem, resulting in a decline in the abundance of pelagic and demersal fish species and a subsequent shift to the predominance of lower-trophic-level functional groups. Finally, we offered some recommendations for improving current fishery management practices.

Exploring the origin of the internal rotational barrier for molecules with one rotatable dihedral angle

PubMed Central

Liu, Shubin; Govind, Niranjan; Pedersen, Lee G.

2008-01-01

Continuing our recent endeavor, we systematically investigate in this work the origin of internal rotational barriers for small molecules using the new energy partition scheme proposed recently by one of the authors [S. B. Liu, J. Chem. Phys. 126, 244103 (2007)], where the total electronic energy is decomposed into three independent components, steric, electrostatic, and fermionic quantum. Specifically, we focus in this work on six carbon, nitrogen, and oxygen containing hydrides, CH3CH3, CH3NH2, CH3OH, NH2NH2, NH2OH, and H2O2, with only one rotatable dihedral angle ∠H–X–Y–H (X,Y=C,N,O). The relative contributions of the different energy components to the total energy difference as a function of the internal dihedral rotation will be considered. Both optimized-geometry (adiabatic) and fixed-geometry (vertical) differences are examined, as are the results from the conventional energy partition and natural bond orbital analysis. A wealth of strong linear relationships among the total energy difference and energy component differences for different systems have been observed but no universal relationship applicable to all systems for both cases has been discovered, indicating that even for simple systems such as these, there exists no omnipresent, unique interpretation on the nature and origin of the internal rotation barrier. Different energy components can be employed for different systems in the rationalization of the barrier height. Confirming that the two differences, adiabatic and vertical, are disparate in nature, we find that for the vertical case there is a unique linear relationship applicable to all the six molecules between the total energy difference and the sum of the kinetic and electrostatic energy differences. For the adiabatic case, it is the total potential energy difference that has been found to correlate well with the total energy difference except for ethane whose rotation barrier is dominated by the quantum effect. PMID:19044862

Thermodynamic analysis of energy density in pressure retarded osmosis: The impact of solution volumes and costs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reimund, Kevin K.; McCutcheon, Jeffrey R.; Wilson, Aaron D.

A general method was developed for estimating the volumetric energy efficiency of pressure retarded osmosis via pressure-volume analysis of a membrane process. The resulting model requires only the osmotic pressure, π, and mass fraction, w, of water in the concentrated and dilute feed solutions to estimate the maximum achievable specific energy density, uu, as a function of operating pressure. The model is independent of any membrane or module properties. This method utilizes equilibrium analysis to specify the volumetric mixing fraction of concentrated and dilute solution as a function of operating pressure, and provides results for the total volumetric energy densitymore » of similar order to more complex models for the mixing of seawater and riverwater. Within the framework of this analysis, the total volumetric energy density is maximized, for an idealized case, when the operating pressure is π/(1+√w⁻¹), which is lower than the maximum power density operating pressure, Δπ/2, derived elsewhere, and is a function of the solute osmotic pressure at a given mass fraction. It was also found that a minimum 1.45 kmol of ideal solute is required to produce 1 kWh of energy while a system operating at “maximum power density operating pressure” requires at least 2.9 kmol. Utilizing this methodology, it is possible to examine the effects of volumetric solution cost, operation of a module at various pressure, and operation of a constant pressure module with various feed.« less

Measurements of electron detection efficiencies in solid state detectors.

NASA Technical Reports Server (NTRS)

Lupton, J. E.; Stone, E. C.

1972-01-01

Detailed laboratory measurement of the electron response of solid state detectors as a function of incident electron energy, detector depletion depth, and energy-loss discriminator threshold. These response functions were determined by exposing totally depleted silicon surface barrier detectors with depletion depths between 50 and 1000 microns to the beam from a magnetic beta-ray spectrometer. The data were extended to 5000 microns depletion depth using the results of previously published Monte Carlo electron calculations. When the electron counting efficiency of a given detector is plotted as a function of energy-loss threshold for various incident energies, the efficiency curves are bounded by a smooth envelope which represents the upper limit to the detection efficiency. These upper limit curves, which scale in a simple way, make it possible to easily estimate the electron sensitivity of solid-state detector systems.

Self-consistent Green's function embedding for advanced electronic structure methods based on a dynamical mean-field concept

NASA Astrophysics Data System (ADS)

Chibani, Wael; Ren, Xinguo; Scheffler, Matthias; Rinke, Patrick

2016-04-01

We present an embedding scheme for periodic systems that facilitates the treatment of the physically important part (here a unit cell or a supercell) with advanced electronic structure methods, that are computationally too expensive for periodic systems. The rest of the periodic system is treated with computationally less demanding approaches, e.g., Kohn-Sham density-functional theory, in a self-consistent manner. Our scheme is based on the concept of dynamical mean-field theory formulated in terms of Green's functions. Our real-space dynamical mean-field embedding scheme features two nested Dyson equations, one for the embedded cluster and another for the periodic surrounding. The total energy is computed from the resulting Green's functions. The performance of our scheme is demonstrated by treating the embedded region with hybrid functionals and many-body perturbation theory in the GW approach for simple bulk systems. The total energy and the density of states converge rapidly with respect to the computational parameters and approach their bulk limit with increasing cluster (i.e., computational supercell) size.

Functional integration of vertical flight path and speed control using energy principles

NASA Technical Reports Server (NTRS)

Lambregts, A. A.

1984-01-01

A generalized automatic flight control system was developed which integrates all longitudinal flight path and speed control functions previously provided by a pitch autopilot and autothrottle. In this design, a net thrust command is computed based on total energy demand arising from both flight path and speed targets. The elevator command is computed based on the energy distribution error between flight path and speed. The engine control is configured to produce the commanded net thrust. The design incorporates control strategies and hierarchy to deal systematically and effectively with all aircraft operational requirements, control nonlinearities, and performance limits. Consistent decoupled maneuver control is achieved for all modes and flight conditions without outer loop gain schedules, control law submodes, or control function duplication.

Analyzing Carbohydrate-Based Regenerative Fuel Cells as a Power Source for Unmanned Aerial Vehicles

DTIC Science & Technology

2008-03-01

conventional means of generating electrical energy, such as turbines and internal combustion engines, in that the conventional methods normally have an...have 24 hours of daylight, this means that it must be able to store enough exergy (the total amount of energy that can theoretically be converted to...useful work, differentiated from useful energy by the efficiency of converting energy to work) to function during the time when exergy consumption is

Convergent evolution of reduced energy demands in extremophile fish

PubMed Central

Arias-Rodriguez, Lenin; Tobler, Michael

2017-01-01

Convergent evolution in organismal function can arise from nonconvergent changes in traits that contribute to that function. Theory predicts that low resource availability and high maintenance costs in extreme environments select for reductions in organismal energy demands, which could be attained through modifications of body size or metabolic rate. We tested for convergence in energy demands and underlying traits by investigating livebearing fish (genus Poecilia) that have repeatedly colonized toxic, hydrogen sulphide-rich springs. We quantified variation in body size and routine metabolism across replicated sulphidic and non-sulphidic populations in nature, modelled total organismal energy demands, and conducted a common-garden experiment to test whether population differences had a genetic basis. Sulphidic populations generally exhibited smaller body sizes and lower routine metabolic rates compared to non-sulphidic populations, which together caused significant reductions in total organismal energy demands in extremophile populations. Although both mechanisms contributed to variation in organismal energy demands, variance partitioning indicated reductions of body size overall had a greater effect than reductions of routine metabolism. Finally, population differences in routine metabolism documented in natural populations were maintained in common-garden reared individuals, indicating evolved differences. In combination with other studies, these results suggest that reductions in energy demands may represent a common theme in adaptation to physiochemical stressors. Selection for reduced energy demand may particularly affect body size, which has implications for life history evolution in extreme environments. PMID:29077740

Association between melanocortin-4 receptor mutations and eating behaviors in obese patients: a case--control study.

PubMed

Valette, M; Poitou, C; Kesse-Guyot, E; Bellisle, F; Carette, C; Le Beyec, J; Hercberg, S; Clément, K; Czernichow, S

2014-06-01

Melanocortin-4 receptor (MC4R) gene mutations are involved in the leptin-melanocortin pathways that control food intake. The effect of these mutations on eating behavior phenotypes is still debated. To determine the association between functional MC4R mutations and eating behaviors, dietary intake and physical activity, we sequenced the MC4R gene in 4653 obese adults. Among them, 19 adults carriers of functional MC4R mutation were matched on age, sex and body mass index with two randomly-paired controls without MC4R mutation (n=57). We found that eating behaviors and physical activity did not differ between groups. In particular, cases were not at increased risk of binge eating disorders. Subjects carriers of MC4R mutation reported a higher proportion of dietary carbohydrates intakes (43.2±7.1 and 39.2±8.1% of total energy intake, respectively, P=0.048) and a lower proportion of dietary lipids (34.3±6.7 and 38.5±6.7% of total energy intake, respectively, P=0.018). In conclusion, mutation carriers differ from controls by a higher consumption of carbohydrates counterbalanced by a lower consumption of lipids expressed as percentage of total energy intake. However, functional MC4R mutations do not have a higher risk of compulsive eating contrary to what was previously suggested.

Teaching Qualitative Energy-Eigenfunction Shape with Physlets

ERIC Educational Resources Information Center

Belloni, Mario; Christian, Wolfgang; Cox, Anne J.

2007-01-01

More than 35 years ago, French and Taylor outlined an approach to teach students and teachers alike how to understand "qualitative plots of bound-state wave functions." They described five fundamental statements based on the quantum-mechanical concepts of probability and energy (total and potential), which could be used to deduce the shape of…

76 FR 20089 - Energy Conservation Program: Energy Conservation Standards for Fluorescent Lamp Ballasts

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-11

... = high output. ** The proposed standards are based on an equation that is a function of the natural... High estimate Discount rate (emerging (existing Primary estimate technologies, roll- technologies, up...$) is the average of the low and high values used in DOE's analysis. [dagger] Total Benefits for both...

Study on conformational stability, molecular structure, vibrational spectra, NBO, TD-DFT, HOMO and LUMO analysis of 3,5-dinitrosalicylic acid by DFT techniques

NASA Astrophysics Data System (ADS)

Sebastian, S.; Sylvestre, S.; Jayabharathi, J.; Ayyapan, S.; Amalanathan, M.; Oudayakumar, K.; Herman, Ignatius A.

2015-02-01

In this work we analyzed the vibrational spectra of 3,5-dinitrosalicylic acid (3,5DNSA) molecule. The total energy of eight possible conformers can be calculated by Density Functional Theory with 6-31G(d,p) as basis set to find the most stable conformer. Computational result identify the most stable conformer of 3,5DNSA is C6. The assignments of the vibrational spectra have been carried out by computing Total Energy Distribution (TED). The molecular geometry, second order perturbation energies and Electron Density (ED) transfer from filled lone pairs of Lewis base to unfilled Lewis acid sites for 3,5-DNSA molecular analyzed on the basis of Natural Bond Orbital (NBO) analysis. The formation of inter and intramolecular hydrogen bonding between sbnd OH and sbnd COOH group gave the evidence for the formation of dimer formation for 3,5-DNSA molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra.

Self-consistent many-electron theory of electron work functions and surface potential characteristics for selected metals

NASA Technical Reports Server (NTRS)

Smith, J. R.

1969-01-01

Electron work functions, surface potentials, and electron number density distributions and electric fields in the surface region of 26 metals were calculated from first principles within the free electron model. Calculation proceeded from an expression of the total energy as a functional of the electron number density, including exchange and correlation energies, as well as a first inhomogeneity term. The self-consistent solution was obtained via a variational procedure. Surface barriers were due principally to many-body effects; dipole barriers were small only for some alkali metals, becoming quite large for the transition metals. Surface energies were inadequately described by this model, which neglects atomistic effects. Reasonable results were obtained for electron work functions and surface potential characteristics, maximum electron densities varying by a factor of over 60.

Probabilistic Forecast of Solar Particle Fluence for Mission Durations and Exposure Assessment in Consideration of Integral Proton Fluence at High Energies

NASA Astrophysics Data System (ADS)

Kim, M. Y.; Tylka, A. J.; Dietrich, W. F.; Cucinotta, F. A.

2012-12-01

The occasional occurrence of solar particle events (SPEs) with large amounts of energy is non-predictable, while the expected frequency is strongly influenced by solar cycle activity. The potential for exposure to large SPEs with high energy levels is the major concern during extra-vehicular activities (EVAs) on the Moon, near Earth object, and Mars surface for future long duration space missions. We estimated the propensity for SPE occurrence with large proton fluence as a function of time within a typical future solar cycle from a non-homogeneous Poisson model using the historical database for measurements of protons with energy > 30 MeV, Φ30. The database includes a comprehensive collection of historical data set for the past 5 solar cycles. Using all the recorded proton fluence of SPEs, total fluence distributions of Φ30, Φ60, and Φ100 were simulated ranging from its 5th to 95th percentile for each mission durations. In addition to the total particle intensity of SPEs, the detailed energy spectra of protons, especially at high energy levels, were recognized as extremely important for assessing the radiation cancer risk associated with energetic particles for large events. For radiation exposure assessments of major SPEs, we used the spectral functional form of a double power law in rigidity (the so-called Band function), which have provided a satisfactory representation of the combined satellite and neutron monitor data from ~10 MeV to ~10 GeV. The dependencies of exposure risk were evaluated as a function of proton fluence at a given energy threshold of 30, 60, and 100 MeV, and overall risk prediction was improved as the energy level threshold increases from 30 to 60 to 100 MeV. The results can be applied to the development of approaches of improved radiation protection for astronauts, as well as the optimization of mission planning and shielding for future space missions.

Ionic strength independence of charge distributions in solvation of biomolecules

NASA Astrophysics Data System (ADS)

Virtanen, J. J.; Sosnick, T. R.; Freed, K. F.

2014-12-01

Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other.

Attenuation of thermal neutrons by an imperfect single crystal

NASA Astrophysics Data System (ADS)

Naguib, K.; Adib, M.

1996-06-01

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3 - 40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range.

Generalized Jastrow Variational Method for Liquid HELIUM-3-HELIUM-4 Mixtures at T = 0 K.

NASA Astrophysics Data System (ADS)

Mirabbaszadeh, Kavoos

Microscopic theory of dilute liquid { ^3 He}-{^4 He} mixtures is of great interest, because it provides a physical realization of a nearly degenerate weakly interacting Fermion system. An understanding of properties of the mixtures has received considerable attention both theoretically and experimentally over the past thirty years. We present here a variational procedure based on the Jastrow function for the ground state of {^3 He}- {^4 He} mixtures by minimizing the total energy of the mixture using the hypernetted-chain (HNC) approximation and the Percus-Yevick (PY) approximation for the two body correlation functions. Our goal is to compute from first principles the internal energy of the system and the various two body correlation functions at various densities and compare the results with experiment. The Jastrow variational method for the ground state energy of liquid {^4 He} consists of the following ansatz for the wave function Psi_alpha {rm(vec r_{1 alpha},} {vec r_{2alpha},} dots, {vec r_{N _alpha})} = prod _{rm i < j} {rm f_ {alphaalpha}(r_{ij}). } For a {^3 He } system the corresponding ansatz is Psi_beta {rm( vec r_{1beta},} {vec r_{2beta },} dots, {vec r_{N_beta})} = {[prod _{i < j} f_{betabeta }(r_{ij})]} Phi {rm( vec r_{1beta},} {vec r_{2beta },} dots, {vec r_{Nbeta}),} where Phi is a Slater determinant of plane waves for the ground state of the Fermion system. The total energy per particle can be written in the form: E = x_sp{alpha}{2} E_{alphaalpha} + x_sp{beta}{2 }E_{betabeta } + 2x_{alpha} x_{beta}E _{alphabeta}, where E_{alphaalpha} , E_{betabeta} , E_{alphabeta} are unknown parameters to be determined from a microscopic theory. Using the Jastrow wave function Psi for the mixture, a general expression is given for the ground state energy in terms of the two body potential and two and three body correlation functions. The Kirkwood Super-position Approximation (KSA) is used for the three-body correlation functions. The antisymmetry of the wave function for Fermions is incorporated following the procedure given earlier by Lado, Inguva and Smith. This procedure for treating the antisymmetry of the wave function simplifies the equations for the two-body correlation functions considerably. The equations for the correlation functions are solved in the hypernetted-chain approximation. Once the two-particle correlation functions for the mixture ( ^3He-^4He) have been obtained, the energy is minimized with respect to the variational parameters involved in the Jastrow wave function. The binding energy and the optimal correlation functions are then obtained as a function of the concentration of ^3He atoms in the mixture. (Abstract shortened with permission of author.).

MN15-L: A New Local Exchange-Correlation Functional for Kohn-Sham Density Functional Theory with Broad Accuracy for Atoms, Molecules, and Solids.

PubMed

Yu, Haoyu S; He, Xiao; Truhlar, Donald G

2016-03-08

Kohn-Sham density functional theory is widely used for applications of electronic structure theory in chemistry, materials science, and condensed-matter physics, but the accuracy depends on the quality of the exchange-correlation functional. Here, we present a new local exchange-correlation functional called MN15-L that predicts accurate results for a broad range of molecular and solid-state properties including main-group bond energies, transition metal bond energies, reaction barrier heights, noncovalent interactions, atomic excitation energies, ionization potentials, electron affinities, total atomic energies, hydrocarbon thermochemistry, and lattice constants of solids. The MN15-L functional has the same mathematical form as a previous meta-nonseparable gradient approximation exchange-correlation functional, MN12-L, but it is improved because we optimized it against a larger database, designated 2015A, and included smoothness restraints; the optimization has a much better representation of transition metals. The mean unsigned error on 422 chemical energies is 2.32 kcal/mol, which is the best among all tested functionals, with or without nonlocal exchange. The MN15-L functional also provides good results for test sets that are outside the training set. A key issue is that the functional is local (no nonlocal exchange or nonlocal correlation), which makes it relatively economical for treating large and complex systems and solids. Another key advantage is that medium-range correlation energy is built in so that one does not need to add damped dispersion by molecular mechanics in order to predict accurate noncovalent binding energies. We believe that the MN15-L functional should be useful for a wide variety of applications in chemistry, physics, materials science, and molecular biology.

Considerations about projectile and target X-rays induced during heavy ion bombardment

NASA Astrophysics Data System (ADS)

Fernandes, F.; Bauer, D. V.; Duarte, A.; Ferrari, T. M.; Niekraszewicz, L. A. B.; Amaral, L.; Dias, J. F.

2018-02-01

In this work we present some results concerning the X-rays emitted by heavy ions during target bombardment. In this case, Cl4+ and Cl5+ ions with energies from 4 MeV to 10 MeV were employed to irradiate vitreous carbon planchets. Moreover, total X-ray production cross sections of titanium X-rays induced by chlorine ions were obtained as well for the same energy range. Only inner shell transitions were considered in the present work. The titanium target consisted of a thin film deposited over vitreous carbon planchets. The results indicate that the projectile X-ray yields increase as a function of the bombarding energy for the present energy range. Effects due to projectile charge state appears to be of minor importance at these low ion velocities. It is shown that a simple exponential function can represent the continuum background of such complex spectra. The chlorine transition rates Kβ/Kα obtained from chlorine acting as a projectile interacting with a carbon target are about half the value when compared to the chlorine Kβ/Kα ratios obtained when a LiCl target is bombarded with C+ and C3+ ions with energies from 2 MeV to 6 MeV. As far as the total X-ray production cross sections of Ti induced by chlorine ions are concerned, the ECPSSR theory underestimates the Ti total X-rays production cross sections by several orders of magnitude. The role of electron capture and possible mechanisms responsible for these effects are discussed.

Topology Trivialization and Large Deviations for the Minimum in the Simplest Random Optimization

NASA Astrophysics Data System (ADS)

Fyodorov, Yan V.; Le Doussal, Pierre

2014-01-01

Finding the global minimum of a cost function given by the sum of a quadratic and a linear form in N real variables over (N-1)-dimensional sphere is one of the simplest, yet paradigmatic problems in Optimization Theory known as the "trust region subproblem" or "constraint least square problem". When both terms in the cost function are random this amounts to studying the ground state energy of the simplest spherical spin glass in a random magnetic field. We first identify and study two distinct large-N scaling regimes in which the linear term (magnetic field) leads to a gradual topology trivialization, i.e. reduction in the total number {N}_{tot} of critical (stationary) points in the cost function landscape. In the first regime {N}_{tot} remains of the order N and the cost function (energy) has generically two almost degenerate minima with the Tracy-Widom (TW) statistics. In the second regime the number of critical points is of the order of unity with a finite probability for a single minimum. In that case the mean total number of extrema (minima and maxima) of the cost function is given by the Laplace transform of the TW density, and the distribution of the global minimum energy is expected to take a universal scaling form generalizing the TW law. Though the full form of that distribution is not yet known to us, one of its far tails can be inferred from the large deviation theory for the global minimum. In the rest of the paper we show how to use the replica method to obtain the probability density of the minimum energy in the large-deviation approximation by finding both the rate function and the leading pre-exponential factor.

Universal binding energy relation for cleaved and structurally relaxed surfaces.

PubMed

Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V

2014-02-05

The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress-displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements.

Comparison of local exchange potentials of electron-N2 scattering

NASA Astrophysics Data System (ADS)

Rumble, J. R., Jr.; Truhlar, D. G.

1980-05-01

Vibrationally and electronically elastic electron scattering by N2 at 2-30 eV impact energy is considered. Static, static-exchange, and static-exchange-plus-polarization potentials, Cade-Sales-Wahl and INDO/1s wave functions, and semiclassical exchange and Hara free-electron-gas exchange potentials are examined. It is shown that the semiclassical exchange approximation is too attractive at low energy for N2. It is also shown quantitatively by consideration of partial and total integral cross sections how the effects of approximations to exchange become smaller as the incident energy is increased until the differences are about 8% for the total integral cross section at 30 eV.

Conformational free energy of melts of ring-linear polymer blends.

PubMed

Subramanian, Gopinath; Shanbhag, Sachin

2009-10-01

The conformational free energy of ring polymers in a blend of ring and linear polymers is investigated using the bond-fluctuation model. Previously established scaling relationships for the free energy of a ring polymer are shown to be valid only in the mean-field sense, and alternative functional forms are investigated. It is shown that it may be difficult to accurately express the total free energy of a ring polymer by a simple scaling argument, or in closed form.

Optimal operation management of fuel cell/wind/photovoltaic power sources connected to distribution networks

NASA Astrophysics Data System (ADS)

Niknam, Taher; Kavousifard, Abdollah; Tabatabaei, Sajad; Aghaei, Jamshid

2011-10-01

In this paper a new multiobjective modified honey bee mating optimization (MHBMO) algorithm is presented to investigate the distribution feeder reconfiguration (DFR) problem considering renewable energy sources (RESs) (photovoltaics, fuel cell and wind energy) connected to the distribution network. The objective functions of the problem to be minimized are the electrical active power losses, the voltage deviations, the total electrical energy costs and the total emissions of RESs and substations. During the optimization process, the proposed algorithm finds a set of non-dominated (Pareto) optimal solutions which are stored in an external memory called repository. Since the objective functions investigated are not the same, a fuzzy clustering algorithm is utilized to handle the size of the repository in the specified limits. Moreover, a fuzzy-based decision maker is adopted to select the 'best' compromised solution among the non-dominated optimal solutions of multiobjective optimization problem. In order to see the feasibility and effectiveness of the proposed algorithm, two standard distribution test systems are used as case studies.

Tests of the SIBYLL 2.3 high-energy hadronic interaction model using the KASCADE-Grande muon data

NASA Astrophysics Data System (ADS)

Arteaga-Velázquez, J. C.; Rivera-Rangel, D.; Apel, W. D.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; Souza, V. de; Pierro, F. Di; Doll, P.; Engel, R.; Fuhrmann, D.; Gherghel-Lascu, A.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Kampert, K. H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Zabierowski, J.

2018-01-01

The KASCADE-Grande observatory was a ground-based air shower array dedicated to study the energy and composition of cosmic rays in the energy interval E = 1 PeV -1 EeV. The experiment consisted of different detector systems which allowed the simultaneous measurement of distinct components of air showers (EAS), such as the muon content. In this contribution, we study the total muon number and the lateral density distribution of muons in EAS detected by KASCADE-Grande as a function of the zenith angle and the total number of charged particles. The attenuation length of the muon content of EAS is also measured. The results are compared with the predictions of the SIBYLL 2.3 high-energy hadronic interaction model.

Computer simulation of surface and film processes

NASA Technical Reports Server (NTRS)

Tiller, W. A.; Halicioglu, M. T.

1983-01-01

Adequate computer methods, based on interactions between discrete particles, provide information leading to an atomic level understanding of various physical processes. The success of these simulation methods, however, is related to the accuracy of the potential energy function representing the interactions among the particles. The development of a potential energy function for crystalline SiO2 forms that can be employed in lengthy computer modelling procedures was investigated. In many of the simulation methods which deal with discrete particles, semiempirical two body potentials were employed to analyze energy and structure related properties of the system. Many body interactions are required for a proper representation of the total energy for many systems. Many body interactions for simulations based on discrete particles are discussed.

Exchange-Hole Dipole Dispersion Model for Accurate Energy Ranking in Molecular Crystal Structure Prediction.

PubMed

Whittleton, Sarah R; Otero-de-la-Roza, A; Johnson, Erin R

2017-02-14

Accurate energy ranking is a key facet to the problem of first-principles crystal-structure prediction (CSP) of molecular crystals. This work presents a systematic assessment of B86bPBE-XDM, a semilocal density functional combined with the exchange-hole dipole moment (XDM) dispersion model, for energy ranking using 14 compounds from the first five CSP blind tests. Specifically, the set of crystals studied comprises 11 rigid, planar compounds and 3 co-crystals. The experimental structure was correctly identified as the lowest in lattice energy for 12 of the 14 total crystals. One of the exceptions is 4-hydroxythiophene-2-carbonitrile, for which the experimental structure was correctly identified once a quasi-harmonic estimate of the vibrational free-energy contribution was included, evidencing the occasional importance of thermal corrections for accurate energy ranking. The other exception is an organic salt, where charge-transfer error (also called delocalization error) is expected to cause the base density functional to be unreliable. Provided the choice of base density functional is appropriate and an estimate of temperature effects is used, XDM-corrected density-functional theory is highly reliable for the energetic ranking of competing crystal structures.

Neural network approach to quantum-chemistry data: accurate prediction of density functional theory energies.

PubMed

Balabin, Roman M; Lomakina, Ekaterina I

2009-08-21

Artificial neural network (ANN) approach has been applied to estimate the density functional theory (DFT) energy with large basis set using lower-level energy values and molecular descriptors. A total of 208 different molecules were used for the ANN training, cross validation, and testing by applying BLYP, B3LYP, and BMK density functionals. Hartree-Fock results were reported for comparison. Furthermore, constitutional molecular descriptor (CD) and quantum-chemical molecular descriptor (QD) were used for building the calibration model. The neural network structure optimization, leading to four to five hidden neurons, was also carried out. The usage of several low-level energy values was found to greatly reduce the prediction error. An expected error, mean absolute deviation, for ANN approximation to DFT energies was 0.6+/-0.2 kcal mol(-1). In addition, the comparison of the different density functionals with the basis sets and the comparison of multiple linear regression results were also provided. The CDs were found to overcome limitation of the QD. Furthermore, the effective ANN model for DFT/6-311G(3df,3pd) and DFT/6-311G(2df,2pd) energy estimation was developed, and the benchmark results were provided.

Collision cross sections of N2 by H+ impact at keV energies within time-dependent density-functional theory

NASA Astrophysics Data System (ADS)

Yu, W.; Gao, C.-Z.; Zhang, Y.; Zhang, F. S.; Hutton, R.; Zou, Y.; Wei, B.

2018-03-01

We calculate electron capture and ionization cross sections of N2 impacted by the H+ projectile at keV energies. To this end, we employ the time-dependent density-functional theory coupled nonadiabatically to molecular dynamics. To avoid the explicit treatment of the complex density matrix in the calculation of cross sections, we propose an approximate method based on the assumption of constant ionization rate over the period of the projectile passing the absorbing boundary. Our results agree reasonably well with experimental data and semi-empirical results within the measurement uncertainties in the considered energy range. The discrepancies are mainly attributed to the inadequate description of exchange-correlation functional and the crude approximation for constant ionization rate. Although the present approach does not predict the experiments quantitatively for collision energies below 10 keV, it is still helpful to calculate total cross sections of ion-molecule collisions within a certain energy range.

Impact of dietary plane of energy during the dry period on lipoprotein parameters in the transition period in dairy cattle.

PubMed

Newman, A; Mann, S; Nydam, D V; Overton, T R; Behling-Kelly, E

2016-02-01

The high energy demands of dairy cows during the transition period from late gestation into early lactation can place them at an increased risk for the development of metabolic and infectious diseases. Modification of the dry period diet has been investigated as a preventive means to minimize the detrimental aspects of metabolic shifts during the transition period. Studies investigating the impact of dry period diet on lipid parameters during the transition period have largely focused on markers of lipolysis and ketogenesis. Total cholesterol declines during the periparturient period and increases in early lactation. The impact total energy in the dry period diet has on the ability of the cow to maintain total serum cholesterol, as well as its natural high-density lipoprotein-rich status, during this metabolically challenging window is not clear. The impact of lipoproteins on inflammation and immune function may have a clinical impact on the cow's ability to ward off production-related diseases. In this study, we hypothesized that the provision of adequate, but not excessive, total metabolizable energy, would better allow the cow to maintain total cholesterol and a higher relative proportion of HDL throughout the transition period. Cows were allocated to one of three dry period dietary treatment groups following a randomized block design. Total serum triglycerides, cholesterol and lipoprotein fractions were measured on a weekly basis from approximately 7 weeks pre-calving to 6 weeks post-calving. The cows on the high energy diet maintained total serum cholesterol as compared to the cows provided a lower energy diet, but there was no significant increase in the LDL fraction of lipoproteins between diet treatment groups. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

Gallium diffusion in zinc oxide via the paired dopant-vacancy mechanism

NASA Astrophysics Data System (ADS)

Sky, T. N.; Johansen, K. M.; Riise, H. N.; Svensson, B. G.; Vines, L.

2018-02-01

Isochronal and isothermal diffusion experiments of gallium (Ga) in zinc oxide (ZnO) have been performed in the temperature range of 900-1050 °C. The samples used consisted of a sputter-deposited and highly Ga-doped ZnO film at the surface of a single-crystal bulk material. We use a novel reaction diffusion (RD) approach to demonstrate that the diffusion behavior of Ga in ZnO is consistent with zinc vacancy (VZn) mediation via the formation and dissociation of GaZnVZn complexes. In the RD modeling, experimental diffusion data are fitted utilizing recent density-functional-theory estimates of the VZn formation energy and the binding energy of GaZnVZn. From the RD modeling, a migration energy of 2.3 eV is deduced for GaZnVZn, and a total/effective activation energy of 3.0 eV is obtained for the Ga diffusion. Furthermore, and for comparison, employing the so-called Fair model, a total/effective activation energy of 2.7 eV is obtained for the Ga diffusion, reasonably close to the total value extracted from the RD-modeling.

Charged-particle multiplicity and pseudorapidity distributions measured with the PHOBOS detector in Au+Au, Cu+Cu, d+Au, and p+p collisions at ultrarelativistic energies

NASA Astrophysics Data System (ADS)

Alver, B.; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Chetluru, V.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kotuła, J.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Li, W.; Lin, W. T.; Loizides, C.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wadsworth, B.; Walters, P.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

2011-02-01

Pseudorapidity distributions of charged particles emitted in Au+Au, Cu+Cu, d+Au, and p+p collisions over a wide energy range have been measured using the PHOBOS detector at the BNL Relativistic Heavy-Ion Collider (RHIC). The centrality dependence of both the charged particle distributions and the multiplicity at midrapidity were measured. Pseudorapidity distributions of charged particles emitted with |η|<5.4, which account for between 95% and 99% of the total charged-particle emission associated with collision participants, are presented for different collision centralities. Both the midrapidity density dNch/dη and the total charged-particle multiplicity Nch are found to factorize into a product of independent functions of collision energy, sNN, and centrality given in terms of the number of nucleons participating in the collision, Npart. The total charged particle multiplicity, observed in these experiments and those at lower energies, assumes a linear dependence of (lnsNN)2 over the full range of collision energy of sNN=2.7-200 GeV.

Theoretical model of ruminant adipose tissue metabolism in relation to the whole animal.

PubMed

Baldwin, R L; Yang, Y T; Crist, K; Grichting, G

1976-09-01

Based on theoretical considerations and experimental data, estimates of contributions of adipose tissue to energy expenditures in a lactating cow and a growing steer were developed. The estimates indicate that adipose energy expenditures range between 5 and 10% of total animal heat production dependent on productive function and diet. These energy expenditures can be partitioned among maintenance (3%), lipogenesis (1-5%) and lipolysis and triglyceride resynthesis (less thatn 1.0%). Specific sites at which acute and chronic effectors can act to produce changes in adipose function, and changes in adipose function produced by diet and during pregnancy, lactation and aging were discussed with emphasis being placed on the need for additional, definitive studies of specific interactions among pregnancy, diet, age, lactation and growth in producing ruminants.

Urinary extracorporeal shock wave lithotripsy: equipment, techniques, and overview.

PubMed

Pfister, R C; Papanicolaou, N; Yoder, I C

1988-01-01

Second generation urinary lithotriptors are characterized by extensive technical alterations and significant equipment improvement in the functional, logistical, and medical aspects of shock wave lithotripsy (SWL). These newer devices feature a water bath-free environment, a reduced anesthesia requirement, improved imaging, functional uses in addition to lithotripsy, or combinations thereof. Shock wave generation by spark gap, electromagnetic, piezoelectric and microexplosive techniques are related to their peak energy, frequency, and total energy capabilities which impacts on both anesthesia needs and the length and number of treatment sessions required to pulverize calculi. A master table summarizes the types of SW energy, coupling, imaging systems, patient transport, functional features, cost, and treatment effectiveness of 12 worldwide lithotriptors in various stages of investigative and clinical trials as monitored by the Food and Drug Administration (FDA) of America.

On the accuracy of density functional theory and wave function methods for calculating vertical ionization energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKechnie, Scott; Booth, George H.; Cohen, Aron J.

The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density-functional theory (DFT) and wave function methods: Hartree-Fock theory (HF), second-order Møller-Plesset perturbation theory (MP2) and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionizationmore » energies obtained from total energy diff calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.« less

Using Wannier functions to improve solid band gap predictions in density functional theory

DOE PAGES

Ma, Jie; Wang, Lin-Wang

2016-04-26

Enforcing a straight-line condition of the total energy upon removal/addition of fractional electrons on eigen states has been successfully applied to atoms and molecules for calculating ionization potentials and electron affinities, but fails for solids due to the extended nature of the eigen orbitals. Here we have extended the straight-line condition to the removal/addition of fractional electrons on Wannier functions constructed within the occupied/unoccupied subspaces. It removes the self-interaction energies of those Wannier functions, and yields accurate band gaps for solids compared to experiments. It does not have any adjustable parameters and the computational cost is at the DFT level.more » This method can also work for molecules, providing eigen energies in good agreement with experimental ionization potentials and electron affinities. Our approach can be viewed as an alternative approach of the standard LDA+U procedure.« less

Some characteristics of intense geomagnetic storms and their energy budget

NASA Astrophysics Data System (ADS)

Vichare, Geeta; Alex, S.; Lakhina, G. S.

2005-03-01

The present study analyses nine intense geomagnetic storms (∣Dst∣ > 175 nT) with the aid of ACE satellite measurements and ground magnetic field values at Alibag Magnetic Observatory. The study confirms the crucial role of southward IMF in triggering the storm main phase as well as controlling the magnitude of the storm. The main phase interval shows clear dependence on the duration of southward IMF. An attempt is made to identify the multipeak signature in the ring current energy injection rate during main phase of the storm. In order to quantify the energy budget of magnetic storms, the present paper computes the solar wind energies, magnetospheric coupling energies, auroral and Joule heating energies, and the ring current energies for each storm under examination. Computation of the solar wind- magnetosphere coupling function considers the variation of the size of the magnetosphere by using the measured solar wind ram pressure. During the main phase of the storm, the solar wind kinetic energy ranges from 9 × 1017 to 72 × 1017 J with an average of 30 × 1017 J; the total energy dissipated in the auroral ionosphere varies between 2 × 1015 and 9 × 1015 J, whereas ring current energies range from 8 × 1015 to 19 × 1015 J. For the total storm period, about 3.5% of total solar wind kinetic energy is available for the redistribution in the magnetosphere, and around 20% of this goes into the inner magnetosphere and in the auroral ionosphere of both the hemispheres. It is found that during main phase of the storm, almost 5% of the total solar wind kinetic energy is available for the redistribution in the magnetosphere, whereas during the recovery phase the percentage becomes 2.3%.

Nonlocal kinetic energy functionals by functional integration.

PubMed

Mi, Wenhui; Genova, Alessandro; Pavanello, Michele

2018-05-14

Since the seminal studies of Thomas and Fermi, researchers in the Density-Functional Theory (DFT) community are searching for accurate electron density functionals. Arguably, the toughest functional to approximate is the noninteracting kinetic energy, T s [ρ], the subject of this work. The typical paradigm is to first approximate the energy functional and then take its functional derivative, δT s [ρ]δρ(r), yielding a potential that can be used in orbital-free DFT or subsystem DFT simulations. Here, this paradigm is challenged by constructing the potential from the second-functional derivative via functional integration. A new nonlocal functional for T s [ρ] is prescribed [which we dub Mi-Genova-Pavanello (MGP)] having a density independent kernel. MGP is constructed to satisfy three exact conditions: (1) a nonzero "Kinetic electron" arising from a nonzero exchange hole; (2) the second functional derivative must reduce to the inverse Lindhard function in the limit of homogenous densities; (3) the potential is derived from functional integration of the second functional derivative. Pilot calculations show that MGP is capable of reproducing accurate equilibrium volumes, bulk moduli, total energy, and electron densities for metallic (body-centered cubic, face-centered cubic) and semiconducting (crystal diamond) phases of silicon as well as of III-V semiconductors. The MGP functional is found to be numerically stable typically reaching self-consistency within 12 iterations of a truncated Newton minimization algorithm. MGP's computational cost and memory requirements are low and comparable to the Wang-Teter nonlocal functional or any generalized gradient approximation functional.

Nonlocal kinetic energy functionals by functional integration

NASA Astrophysics Data System (ADS)

Mi, Wenhui; Genova, Alessandro; Pavanello, Michele

2018-05-01

Since the seminal studies of Thomas and Fermi, researchers in the Density-Functional Theory (DFT) community are searching for accurate electron density functionals. Arguably, the toughest functional to approximate is the noninteracting kinetic energy, Ts[ρ], the subject of this work. The typical paradigm is to first approximate the energy functional and then take its functional derivative, δ/Ts[ρ ] δ ρ (r ) , yielding a potential that can be used in orbital-free DFT or subsystem DFT simulations. Here, this paradigm is challenged by constructing the potential from the second-functional derivative via functional integration. A new nonlocal functional for Ts[ρ] is prescribed [which we dub Mi-Genova-Pavanello (MGP)] having a density independent kernel. MGP is constructed to satisfy three exact conditions: (1) a nonzero "Kinetic electron" arising from a nonzero exchange hole; (2) the second functional derivative must reduce to the inverse Lindhard function in the limit of homogenous densities; (3) the potential is derived from functional integration of the second functional derivative. Pilot calculations show that MGP is capable of reproducing accurate equilibrium volumes, bulk moduli, total energy, and electron densities for metallic (body-centered cubic, face-centered cubic) and semiconducting (crystal diamond) phases of silicon as well as of III-V semiconductors. The MGP functional is found to be numerically stable typically reaching self-consistency within 12 iterations of a truncated Newton minimization algorithm. MGP's computational cost and memory requirements are low and comparable to the Wang-Teter nonlocal functional or any generalized gradient approximation functional.

Stability of boundary layer flow based on energy gradient theory

NASA Astrophysics Data System (ADS)

Dou, Hua-Shu; Xu, Wenqian; Khoo, Boo Cheong

2018-05-01

The flow of the laminar boundary layer on a flat plate is studied with the simulation of Navier-Stokes equations. The mechanisms of flow instability at external edge of the boundary layer and near the wall are analyzed using the energy gradient theory. The simulation results show that there is an overshoot on the velocity profile at the external edge of the boundary layer. At this overshoot, the energy gradient function is very large which results in instability according to the energy gradient theory. It is found that the transverse gradient of the total mechanical energy is responsible for the instability at the external edge of the boundary layer, which induces the entrainment of external flow into the boundary layer. Within the boundary layer, there is a maximum of the energy gradient function near the wall, which leads to intensive flow instability near the wall and contributes to the generation of turbulence.

Measurement of the inclusive energy spectrum in the very forward direction in proton-proton collisions at $$ \\sqrt{s}=13 $$ TeV

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2017-08-11

The differential cross section for inclusive particle production as a function of energy in proton-proton collisions at a center-of-mass energy of 13 TeV is measured in the very forward region of the CMS detector. The measurement is based on data collected with the CMS apparatus at the LHC, and corresponds to an integrated luminosity of 0.34 μb –1. The energy is measured in the CASTOR calorimeter, which covers the pseudorapidity region -6.6 < η < -5.2. The results are given as a function of the total energy deposited in CASTOR, as well as of its electromagnetic and hadronic components. Furthermore,more » the spectra are sensitive to the modeling of multiparton interactions in pp collisions, and provide new constraints for hadronic interaction models used in collider and in high energy cosmic ray physics.« less

Electron and proton absorption calculations for a graphite/epoxy composite model. [large space structures

NASA Technical Reports Server (NTRS)

Long, E. R., Jr.

1979-01-01

The Bethe-Bloch stopping power relations for inelastic collisions were used to determine the absorption of electron and proton energy in cured neat epoxy resin and the absorption of electron energy in a graphite/epoxy composite. Absorption of electron energy due to bremsstrahlung was determined. Electron energies from 0.2 to 4.0 MeV and proton energies from 0.3 to 1.75 MeV were used. Monoenergetic electron energy absorption profiles for models of pure graphite, cured neat epoxy resin, and graphite/epoxy composites are reported. A relation is determined for depth of uniform energy absorption in a composite as a function of fiber volume fraction and initial electron energy. Monoenergetic proton energy absorption profiles are reported for the neat resin model. A relation for total proton penetration in the epoxy resin as a function of initial proton energy is determined. Electron energy absorption in the composite due to bremsstrahlung is reported. Electron and proton energy absorption profiles in cured neat epoxy resin are reported for environments approximating geosynchronous earth orbit.

Note: The performance of new density functionals for a recent blind test of non-covalent interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mardirossian, Narbe; Head-Gordon, Martin

Benchmark datasets of non-covalent interactions are essential for assessing the performance of density functionals and other quantum chemistry approaches. In a recent blind test, Taylor et al. benchmarked 14 methods on a new dataset consisting of 10 dimer potential energy curves calculated using coupled cluster with singles, doubles, and perturbative triples (CCSD(T)) at the complete basis set (CBS) limit (80 data points in total). Finally, the dataset is particularly interesting because compressed, near-equilibrium, and stretched regions of the potential energy surface are extensively sampled.

Note: The performance of new density functionals for a recent blind test of non-covalent interactions

DOE PAGES

Mardirossian, Narbe; Head-Gordon, Martin

2016-11-09

Benchmark datasets of non-covalent interactions are essential for assessing the performance of density functionals and other quantum chemistry approaches. In a recent blind test, Taylor et al. benchmarked 14 methods on a new dataset consisting of 10 dimer potential energy curves calculated using coupled cluster with singles, doubles, and perturbative triples (CCSD(T)) at the complete basis set (CBS) limit (80 data points in total). Finally, the dataset is particularly interesting because compressed, near-equilibrium, and stretched regions of the potential energy surface are extensively sampled.

Bound states and propagating modes in quantum wires with sharp bends and/or constrictions

NASA Astrophysics Data System (ADS)

Razavy, M.

1997-06-01

A number of interesting problems of quantum wires with different geometries can be studied with the help of conformal mapping. These include crossed wires, twisting wires, conductors with constrictions, and wires with a bend. Here the Helmholz equation with Dirichlet boundary condition on the surface of the wire is transformed to a Schröautdinger-like equation with an energy-dependent nonseparable potential but with boundary conditions given on two straight lines. By expanding the wave function in terms of the Fourier series of one of the variables one obtains an infinite set of coupled ordinary differential equations. Only the propagating modes plus a few of the localized modes contribute significantly to the total wave function. Once the problem is solved, one can express the results in terms of the original variables using the inverse conformal mapping. As an example, the total wave function, the components of the current density, and the bound-state energy for a Γ-shaped quantum wire is calculated in detail.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Depriest, Kendall

Unsuccessful attempts by members of the radiation effects community to independently derive the Norgett-Robinson-Torrens (NRT) damage energy factors for silicon in ASTM standard E722-14 led to an investigation of the software coding and data that produced those damage energy factors. The ad hoc collaboration to discover the reason for lack of agreement revealed a coding error and resulted in a report documenting the methodology to produce the response function for the standard. The recommended changes in the NRT damage energy factors for silicon are shown to have significant impact for a narrow energy region of the 1-MeV(Si) equivalent fluence responsemore » function. However, when evaluating integral metrics over all neutrons energies in various spectra important to the SNL electronics testing community, the change in the response results in a small decrease in the total 1- MeV(Si) equivalent fluence of ~0.6% compared to the E722-14 response. Response functions based on the newly recommended NRT damage energy factors have been produced and are available for users of both the NuGET and MCNP codes.« less

An Analysis of energy consumption and economic growth of Cobb-Douglas production function based on ECM

NASA Astrophysics Data System (ADS)

Guo, Wei-wei

2018-02-01

Energy is one of the important factors affecting economic growth, the motive force of the economic development of countries in the world, essential for the world economic development and people’s living material resources, an important resource of the relationship between the national economies. The paper sums up the evaluation and literatures on energy consumption and economic growth at home and abroad, thinks “southern talk” as the energy consumption and economic growth in the time division, makes a series of empirical tests on the relationship between total energy consumption and economic growth in China from 1978 to 1991 and from 1992 to 2016.The results show that total energy consumption is a one-way causal relationship between economic growths in china, Economic growth has a strong dependence on energy, there is a co-integration relationship between energy consumption and economic growth. However, economic growth depends on the energy consumption decreased year by year in China, The way of economic growth is changing from the extensive economic growth mode to intensive mode of economic growth.

Combining Density Functional Theory and Green's Function Theory: Range-Separated, Nonlocal, Dynamic, and Orbital-Dependent Hybrid Functional.

PubMed

Kananenka, Alexei A; Zgid, Dominika

2017-11-14

We present a rigorous framework which combines single-particle Green's function theory with density functional theory based on a separation of electron-electron interactions into short- and long-range components. Short-range contribution to the total energy and exchange-correlation potential is provided by a density functional approximation, while the long-range contribution is calculated using an explicit many-body Green's function method. Such a hybrid results in a nonlocal, dynamic, and orbital-dependent exchange-correlation functional of a single-particle Green's function. In particular, we present a range-separated hybrid functional called srSVWN5-lrGF2 which combines the local-density approximation and the second-order Green's function theory. We illustrate that similarly to density functional approximations, the new functional is weakly basis-set dependent. Furthermore, it offers an improved description of the short-range dynamic correlation. The many-body contribution to the functional mitigates the many-electron self-interaction error present in many density functional approximations and provides a better description of molecular properties. Additionally, we illustrate that the new functional can be used to scale down the self-energy and, therefore, introduce an additional sparsity to the self-energy matrix that in the future can be exploited in calculations for large molecules or periodic systems.

Study of dust particle charging in weakly ionized inert gases taking into account the nonlocality of the electron energy distribution function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filippov, A. V., E-mail: fav@triniti.ru; Dyatko, N. A.; Kostenko, A. S.

2014-11-15

The charging of dust particles in weakly ionized inert gases at atmospheric pressure has been investigated. The conditions under which the gas is ionized by an external source, a beam of fast electrons, are considered. The electron energy distribution function in argon, krypton, and xenon has been calculated for three rates of gas ionization by fast electrons: 10{sup 13}, 10{sup 14}, and 10{sup 15} cm{sup −1}. A model of dust particle charging with allowance for the nonlocal formation of the electron energy distribution function in the region of strong plasma quasi-neutrality violation around the dust particle is described. The nonlocalitymore » is taken into account in an approximation where the distribution function is a function of only the total electron energy. Comparative calculations of the dust particle charge with and without allowance for the nonlocality of the electron energy distribution function have been performed. Allowance for the nonlocality is shown to lead to a noticeable increase in the dust particle charge due to the influence of the group of hot electrons from the tail of the distribution function. It has been established that the screening constant virtually coincides with the smallest screening constant determined according to the asymptotic theory of screening with the electron transport and recombination coefficients in an unperturbed plasma.« less

Solving the Schroedinger Equation of Atoms and Molecules without Analytical Integration Based on the Free Iterative-Complement-Interaction Wave Function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakatsuji, H.; Nakashima, H.; Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510

2007-12-14

A local Schroedinger equation (LSE) method is proposed for solving the Schroedinger equation (SE) of general atoms and molecules without doing analytic integrations over the complement functions of the free ICI (iterative-complement-interaction) wave functions. Since the free ICI wave function is potentially exact, we can assume a flatness of its local energy. The variational principle is not applicable because the analytic integrations over the free ICI complement functions are very difficult for general atoms and molecules. The LSE method is applied to several 2 to 5 electron atoms and molecules, giving an accuracy of 10{sup -5} Hartree in total energy.more » The potential energy curves of H{sub 2} and LiH molecules are calculated precisely with the free ICI LSE method. The results show the high potentiality of the free ICI LSE method for developing accurate predictive quantum chemistry with the solutions of the SE.« less

Initial Stage of Aerosol Formation from Oversaturated Vapors

NASA Astrophysics Data System (ADS)

Lushnikov, A. A.; Zagainov, V. A.; Lyubovtseva, Yu. S.

2018-03-01

The formation of aerosol particles from oversaturated vapor was considered assuming that the stable nuclei of the new phase contain two (dimers) or three (trimers) condensing vapor molecules. Exact expressions were derived and analyzed for the partition functions of the dimer and trimer suspended in a carrier gas for the rectangular well and repulsive core intermolecular potentials. The equilibrium properties of these clusters and the nucleation rate of aerosol particles were discussed. The bound states of clusters were introduced using a limitation on their total energy: molecular clusters with a negative total energy were considered to exclude configurations with noninteracting fragments.

An aPPARent Functional Consequence in Skeletal Muscle Physiology via Peroxisome Proliferator-Activated Receptors.

PubMed

Phua, Wendy Wen Ting; Wong, Melissa Xin Yu; Liao, Zehuan; Tan, Nguan Soon

2018-05-10

Skeletal muscle comprises 30⁻40% of the total body mass and plays a central role in energy homeostasis in the body. The deregulation of energy homeostasis is a common underlying characteristic of metabolic syndrome. Over the past decades, peroxisome proliferator-activated receptors (PPARs) have been shown to play critical regulatory roles in skeletal muscle. The three family members of PPAR have overlapping roles that contribute to the myriad of processes in skeletal muscle. This review aims to provide an overview of the functions of different PPAR members in energy homeostasis as well as during skeletal muscle metabolic disorders, with a particular focus on human and relevant mouse model studies.

FAST TRACK COMMUNICATION: Finite-temperature magnetism in bcc Fe under compression

NASA Astrophysics Data System (ADS)

Sha, Xianwei; Cohen, R. E.

2010-09-01

We investigate the contributions of finite-temperature magnetic fluctuations to the thermodynamic properties of bcc Fe as functions of pressure. First, we apply a tight-binding total-energy model parameterized to first-principles linearized augmented plane-wave computations to examine various ferromagnetic, anti-ferromagnetic, and noncollinear spin spiral states at zero temperature. The tight-binding data are fit to a generalized Heisenberg Hamiltonian to describe the magnetic energy functional based on local moments. We then use Monte Carlo simulations to compute the magnetic susceptibility, the Curie temperature, heat capacity, and magnetic free energy. Including the finite-temperature magnetism improves the agreement with experiment for the calculated thermal expansion coefficients.

An aPPARent Functional Consequence in Skeletal Muscle Physiology via Peroxisome Proliferator-Activated Receptors

PubMed Central

Phua, Wendy Wen Ting; Wong, Melissa Xin Yu; Liao, Zehuan

2018-01-01

Skeletal muscle comprises 30–40% of the total body mass and plays a central role in energy homeostasis in the body. The deregulation of energy homeostasis is a common underlying characteristic of metabolic syndrome. Over the past decades, peroxisome proliferator-activated receptors (PPARs) have been shown to play critical regulatory roles in skeletal muscle. The three family members of PPAR have overlapping roles that contribute to the myriad of processes in skeletal muscle. This review aims to provide an overview of the functions of different PPAR members in energy homeostasis as well as during skeletal muscle metabolic disorders, with a particular focus on human and relevant mouse model studies. PMID:29747466

Jacob's Ladder as Sketched by Escher: Assessing the Performance of Broadly Used Density Functionals on Transition Metal Surface Properties.

PubMed

Vega, Lorena; Ruvireta, Judit; Viñes, Francesc; Illas, Francesc

2018-01-09

The present work surveys the performance of various widely used density functional theory exchange-correlation (xc) functionals in describing observable surface properties of a total of 27 transition metals with face-centered cubic (fcc), body-centered cubic (bcc), or hexagonal close-packed (hcp) crystallographic structures. A total of 81 low Miller index surfaces were considered employing slab models. Exemplary xc functionals within the three first rungs of Jacob's ladder were considered, including the Vosko-Wilk-Nusair xc functional within the local density approximation, the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA), and the Tao-Perdew-Staroverov-Scuseria functional as a meta-GGA functional. Hybrids were excluded in the survey because they are known to fail in properly describing metallic systems. In addition, two variants of PBE were considered, PBE adapted for solids (PBEsol) and revised PBE (RPBE), aimed at improving adsorption energies. Interlayer atomic distances, surface energies, and surface work functions were chosen as the scrutinized properties. A comparison with available experimental data, including single-crystal and polycrystalline values, shows that no xc functional is best at describing all of the surface properties. However, in statistical mean terms the PBEsol xc functional is advised, while PBE is recommended when considering both bulk and surface properties. On the basis of the present results, a discussion of adapting GGA functionals to the treatment of metallic surfaces in an alternative way to meta-GGA or hybrids is provided.

A Comparison of Energy Provision by Diet Order in a Long-Term Care Facility

ERIC Educational Resources Information Center

Durant, Matthew

2008-01-01

Involuntary weight loss (IWL) is common in the North American elderly population and affects as many as 60 per cent of nursing home residents, representing a threat to health and function. Investigation into nutrient provision in a long-term care (LTC) centre showed that mean total energy exposure over the 5-week menu cycle differed significantly…

Experimental and theoretical studies on solar energy for energy conversion

NASA Technical Reports Server (NTRS)

Thomas, A. P.; Thekaekara, M. P.

1976-01-01

This paper presents the results of investigations made experimentally and theoretically to evaluate the various parameters that affect the amount of solar energy received on a collector surface. Measurements were made over a long period of time using both pyranometer and pyrheliometer. Computation of spectral and total irradiance at ground level have been made for a large variety of combinations of atmospheric parameters for ozone density, precipitable water vapor, turbidity-coefficients and air mass. A study of the air mass as a function of irradiance measured at GSFC, and comparison of the data with the computed values of total direct solar irradiance for various parameters indicate that turbidity changes with time of the day; atmospheric opacity is less in the afternoon than in the morning.

Construction of exchange-correlation functionals through interpolation between the non-interacting and the strong-correlation limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yongxi; Ernzerhof, Matthias, E-mail: Matthias.Ernzerhof@UMontreal.ca; Bahmann, Hilke

Drawing on the adiabatic connection of density functional theory, exchange-correlation functionals of Kohn-Sham density functional theory are constructed which interpolate between the extreme limits of the electron-electron interaction strength. The first limit is the non-interacting one, where there is only exchange. The second limit is the strong correlated one, characterized as the minimum of the electron-electron repulsion energy. The exchange-correlation energy in the strong-correlation limit is approximated through a model for the exchange-correlation hole that is referred to as nonlocal-radius model [L. O. Wagner and P. Gori-Giorgi, Phys. Rev. A 90, 052512 (2014)]. Using the non-interacting and strong-correlated extremes, variousmore » interpolation schemes are presented that yield new approximations to the adiabatic connection and thus to the exchange-correlation energy. Some of them rely on empiricism while others do not. Several of the proposed approximations yield the exact exchange-correlation energy for one-electron systems where local and semi-local approximations often fail badly. Other proposed approximations generalize existing global hybrids by using a fraction of the exchange-correlation energy in the strong-correlation limit to replace an equal fraction of the semi-local approximation to the exchange-correlation energy in the strong-correlation limit. The performance of the proposed approximations is evaluated for molecular atomization energies, total atomic energies, and ionization potentials.« less

Molecular dynamics and quasidynamics simulations of the annealing of bulk and near-surface interstitials formed in molecular-beam epitaxial Si due to low-energy particle bombardment during deposition

NASA Technical Reports Server (NTRS)

Kitabatake, M.; Fons, P.; Greene, J. E.

1991-01-01

The relaxation, diffusion, and annihilation of split and hexagonal interstitials resulting from 10 eV Si irradiation of (2x1)-terminated Si(100) are investigated. Molecular dynamics and quasidynamics simulations, utilizing the Tersoff many-body potential are used in the investigation. The interstitials are created in layers two through six, and stable atomic configurations and total potential energies are derived as a function of site symmetry and layer depth. The interstitial Si atoms are allowed to diffuse, and the total potential energy changes are calculated. Lattice configurations along each path, as well as the starting configurations, are relaxed, and minimum energy diffusion paths are derived. The results show that the minimum energy paths are toward the surface and generally involved tetrahedral sites. The calculated interstitial migration activation energies are always less than 1.4 eV and are much lower in the near-surface region than in the bulk.

Relativistic differential-difference momentum operators and noncommutative differential calculus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mir-Kasimov, R. M., E-mail: mirkr@theor.jinr.ru

2013-09-15

The relativistic kinetic momentum operators are introduced in the framework of the Quantum Mechanics (QM) in the Relativistic Configuration Space (RCS). These operators correspond to the half of the non-Euclidean distance in the Lobachevsky momentum space. In terms of kinetic momentum operators the relativistic kinetic energy is separated as the independent term of the total Hamiltonian. This relativistic kinetic energy term is not distinguishing in form from its nonrelativistic counterpart. The role of the plane wave (wave function of the motion with definite value of momentum and energy) plays the generating function for the matrix elements of the unitary irrepsmore » of Lorentz group (generalized Jacobi polynomials). The kinetic momentum operators are the interior derivatives in the framework of the noncommutative differential calculus over the commutative algebra generated by the coordinate functions over the RCS.« less

A second-order unconstrained optimization method for canonical-ensemble density-functional methods

NASA Astrophysics Data System (ADS)

Nygaard, Cecilie R.; Olsen, Jeppe

2013-03-01

A second order converging method of ensemble optimization (SOEO) in the framework of Kohn-Sham Density-Functional Theory is presented, where the energy is minimized with respect to an ensemble density matrix. It is general in the sense that the number of fractionally occupied orbitals is not predefined, but rather it is optimized by the algorithm. SOEO is a second order Newton-Raphson method of optimization, where both the form of the orbitals and the occupation numbers are optimized simultaneously. To keep the occupation numbers between zero and two, a set of occupation angles is defined, from which the occupation numbers are expressed as trigonometric functions. The total number of electrons is controlled by a built-in second order restriction of the Newton-Raphson equations, which can be deactivated in the case of a grand-canonical ensemble (where the total number of electrons is allowed to change). To test the optimization method, dissociation curves for diatomic carbon are produced using different functionals for the exchange-correlation energy. These curves show that SOEO favors symmetry broken pure-state solutions when using functionals with exact exchange such as Hartree-Fock and Becke three-parameter Lee-Yang-Parr. This is explained by an unphysical contribution to the exact exchange energy from interactions between fractional occupations. For functionals without exact exchange, such as local density approximation or Becke Lee-Yang-Parr, ensemble solutions are favored at interatomic distances larger than the equilibrium distance. Calculations on the chromium dimer are also discussed. They show that SOEO is able to converge to ensemble solutions for systems that are more complicated than diatomic carbon.

Calculations of Flowfield About Indented Nosetips,

DTIC Science & Technology

1982-08-23

agreement is good. UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAOE(ft,. Date E -t. , - NSWC TR 82-286 FOREWORD A finite difference computer program has been...Specific heat at constant pressure and volume respectively e Total energy per unit volume E ,F,H,R,S,T Functions of U AHT, HT Error in total enthalpy and...total enthalpy respectively ijGrid index in E and n directions respectively SI Identity matrix J,K Maximum grid point in E and n directions respectively

Adenylate Energy Pool and Energy Charge in Maturing Rape Seeds 1

PubMed Central

Ching, Te May; Crane, Jim M.; Stamp, David L.

1974-01-01

A study of energy state and chemical composition of pod walls and seeds of maturing rape (Brassica napus L.) was conducted on two varieties, Victor and Gorczanski. Total adenosine phosphates, ATP, and adenylate energy charge increased with increasing cell number and cellular synthesis during the early stages, remained high at maximum dry weight accumulation and maximum substrate influx time, and decreased with ripening. A temporal control of energy supply and ATP concentration is evident in developing tissues with determined functions; whereas the association of a high energy charge and active cellular biosynthesis occurs only in tissues with a stabilized cell number. PMID:16658964

Second order Møller-Plesset and coupled cluster singles and doubles methods with complex basis functions for resonances in electron-molecule scattering

DOE PAGES

White, Alec F.; Epifanovsky, Evgeny; McCurdy, C. William; ...

2017-06-21

The method of complex basis functions is applied to molecular resonances at correlated levels of theory. Møller-Plesset perturbation theory at second order and equation-of-motion electron attachment coupled-cluster singles and doubles (EOM-EA-CCSD) methods based on a non-Hermitian self-consistent-field reference are used to compute accurate Siegert energies for shape resonances in small molecules including N 2 - , CO - , CO 2 - , and CH 2 O - . Analytic continuation of complex θ-trajectories is used to compute Siegert energies, and the θ-trajectories of energy differences are found to yield more consistent results than those of total energies.more » Furthermore, the ability of such methods to accurately compute complex potential energy surfaces is investigated, and the possibility of using EOM-EA-CCSD for Feshbach resonances is explored in the context of e-helium scattering.« less

Second order Møller-Plesset and coupled cluster singles and doubles methods with complex basis functions for resonances in electron-molecule scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Alec F.; Epifanovsky, Evgeny; McCurdy, C. William

The method of complex basis functions is applied to molecular resonances at correlated levels of theory. Møller-Plesset perturbation theory at second order and equation-of-motion electron attachment coupled-cluster singles and doubles (EOM-EA-CCSD) methods based on a non-Hermitian self-consistent-field reference are used to compute accurate Siegert energies for shape resonances in small molecules including N 2 - , CO - , CO 2 - , and CH 2 O - . Analytic continuation of complex θ-trajectories is used to compute Siegert energies, and the θ-trajectories of energy differences are found to yield more consistent results than those of total energies.more » Furthermore, the ability of such methods to accurately compute complex potential energy surfaces is investigated, and the possibility of using EOM-EA-CCSD for Feshbach resonances is explored in the context of e-helium scattering.« less

Intermediate photovoltaic system application experiment operational performance report. Volume 6: Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-03-01

Performance data are given for the month of February, 1982 for a photovoltaic power supply at a Massachusetts high school. Data given include: monthly and daily electrical energy yield; monthly and daily insolation; monthly and daily array efficiency; energy production as a function of power level, voltage, cell temperature, and hour of day; insolation as a function of hour of the day; input, output and efficiency for each of two power conditioning units and for the total power conditioning system; energy supplied to the load by the photovoltaic system and by the grid; photovoltaic system efficiency; dollar value of the energy supplied by the photovoltaic system; capacity factor; daily photovoltaic energy to load; daily system availability and hours of daylight; heating and cooling degree days; hourly cell temperature, ambient temperature, wind speed, and insolation; average monthly wind speed; wind direction distribution; and daily data acquisition mode and recording interval plot.

How to calculate H3 better.

PubMed

Pavanello, Michele; Tung, Wei-Cheng; Adamowicz, Ludwik

2009-11-14

Efficient optimization of the basis set is key to achieving a very high accuracy in variational calculations of molecular systems employing basis functions that are explicitly dependent on the interelectron distances. In this work we present a method for a systematic enlargement of basis sets of explicitly correlated functions based on the iterative-complement-interaction approach developed by Nakatsuji [Phys. Rev. Lett. 93, 030403 (2004)]. We illustrate the performance of the method in the variational calculations of H(3) where we use explicitly correlated Gaussian functions with shifted centers. The total variational energy (-1.674 547 421 Hartree) and the binding energy (-15.74 cm(-1)) obtained in the calculation with 1000 Gaussians are the most accurate results to date.

Electronic properties of the interface between hexadecafluoro copper phthalocyanine and unsubstituted copper phthalocyanine films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komolov, A. S., E-mail: akomolov07@ya.ru; Lazneva, E. F.; Pshenichnyuk, S. A.

2013-07-15

The formation of an interface during the deposition of unsubstituted copper phthalocyanine (CuPc) films on the surface of hexadecafluoro copper phthalocyanine (F{sub 16}-CuPc) films is studied. An incident low-energy electron beam with energies from 0 to 25 eV is used to test the surface under study according to the very-low-energy electron-diffraction technique (VLEED) in the mode of total current spectroscopy. For F{sub 16}-CuPc films, the structure of the maxima in the total current spectra and its main differences from the structure of the maxima for the CuPc film are determined in the energy range from 5 to 15 eV abovemore » the Fermi level. The differences in the structure of vacant electron orbitals for CuPc and F{sub 16}-CuPc are also revealed using density functional theory calculations. As a result of an analysis of variations in the intensities of the total current spectra of the CuPc and F{sub 16}-CuPc films, it is assumed that an intermediate layer up to 1 nm thick appears during the formation of an interface between these films, which is characterized by a spread of the features in the total current spectrum. The height, width, and change in the work function are determined for the studied F{sub 16}-CuPc/NuPc interface barrier. A decrease in the level of vacuum by 0.7 eV occurs in the boundary region, which corresponds to electron density transfer from the CuPc film toward the F{sub 16}-CuPc substrate.« less

Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory.

PubMed

Isegawa, Miho; Gao, Jiali; Truhlar, Donald G

2011-08-28

Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi-Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi-Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred. © 2011 American Institute of Physics

Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory

PubMed Central

Isegawa, Miho; Gao, Jiali; Truhlar, Donald G.

2011-01-01

Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi–Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi–Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred. PMID:21895159

Positive energy conditions in 4D conformal field theory

DOE PAGES

Farnsworth, Kara; Luty, Markus A.; Prilepina, Valentina

2016-10-03

Here, we argue that all consistent 4D quantum field theories obey a spacetime-averaged weak energy inequality < T 00 > ≥ –C/L 4, where L is the size of the smearing region, and C is a positive constant that depends on the theory. If this condition is violated, the theory has states that are indistinguishable from states of negative total energy by any local measurement, and we expect instabilities or other inconsistencies. We apply this condition to 4D conformal field theories, and find that it places constraints on the OPE coefficients of the theory. The constraints we find are weakermore » than the “conformal collider” constraints of Hofman and Maldacena. In 3D CFTs, the only constraint we find is equivalent to the positivity of 2-point function of the energy-momentum tensor, which follows from unitarity. Our calculations are performed using momentum-space Wightman functions, which are remarkably simple functions of momenta, and may be of interest in their own right.« less

Quantification of the Relationship between Surrogate Fuel Structure and Performance

DTIC Science & Technology

2012-07-31

order to account for know deficiencies [18]. The frequencies are then used to calculate the zero point energy ( ZPE ). In the G3 theory HF/6-31G* was used...for the ZPE and the new procedure is likely to be more reliable. Also in contrast to previous G series composite methods, the Hartree–Fock energy...The total energy is obtained by adding the previously calculated ZPE . Durant and Rohlfing [38] reported that B3LYP density functional methods provide

Variational Dirac-Hartree-Fock calculation of the Breit interaction

NASA Astrophysics Data System (ADS)

Goldman, S. P.

1988-04-01

The calculation of the retarded version of the Breit interaction in the context of the VDHF method is discussed. With the use of Slater-type basis functions, all the terms involved can be calculated in closed form. The results are expressed as an expansion in powers of one-electron energy differences and linear combinations of hypergeometric functions. Convergence is fast and high accuracy is obtained with a small number of terms in the expansion even for high values of the nuclear charge. An added advantage is that the lowest order cancellations occurring in the retardation terms are accounted for exactly a priori. A comparison of the number of terms in the total expansion needed for an accuracy of 12 significant digits in the total energy, as well as a comparison of the results with an without retardation and in the local potential approximation, are presented for the carbon isoelectronic sequence.

Linearized self-consistent GW approach satisfying the Ward identity

NASA Astrophysics Data System (ADS)

Kuwahara, Riichi; Ohno, Kaoru

2014-09-01

We propose a linearized self-consistent GW approach satisfying the Ward identity. The vertex function derived from the Ward-Takahashi identity in the limit of q =0 and ω -ω'=0 is included in the self-energy and the polarization function as a consequence of the linearization of the quasiparticle equation. Due to the energy dependence of the self-energy, the Hamiltonian is a non-Hermitian operator and quasiparticle states are nonorthonormal and linearly dependent. However, the linearized quasiparticle states recover orthonormality and fulfill the completeness condition. This approach is very efficient, and the resulting quasiparticle energies are greatly improved compared to the nonlinearized self-consistent GW approach, although its computational cost is not much increased. We show the results for atoms and dimers of Li and Na compared with other approaches. We also propose convenient ways to calculate the Luttinger-Ward functional Φ based on a plasmon-pole model and calculate the total energy for the ground state. As a result, we conclude that the linearization improves overall behaviors in the self-consistent GW approach.

Impact of ASTM Standard E722 update on radiation damage metrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

DePriest, Kendall Russell

2014-06-01

The impact of recent changes to the ASTM Standard E722 is investigated. The methodological changes in the production of the displacement kerma factors for silicon has significant impact for some energy regions of the 1-MeV(Si) equivalent fluence response function. When evaluating the integral over all neutrons energies in various spectra important to the SNL electronics testing community, the change in the response results in an increase in the total 1-MeV(Si) equivalent fluence of 2 7%. Response functions have been produced and are available for users of both the NuGET and MCNP codes.

On-the-Fly Machine Learning of Atomic Potential in Density Functional Theory Structure Optimization

NASA Astrophysics Data System (ADS)

Jacobsen, T. L.; Jørgensen, M. S.; Hammer, B.

2018-01-01

Machine learning (ML) is used to derive local stability information for density functional theory calculations of systems in relation to the recently discovered SnO2 (110 )-(4 ×1 ) reconstruction. The ML model is trained on (structure, total energy) relations collected during global minimum energy search runs with an evolutionary algorithm (EA). While being built, the ML model is used to guide the EA, thereby speeding up the overall rate by which the EA succeeds. Inspection of the local atomic potentials emerging from the model further shows chemically intuitive patterns.

The fcc - bcc structural transition: I. A band theoretical study for Li, K, Rb, Ca, Sr, and the transition metals Ti and V

NASA Astrophysics Data System (ADS)

Sliwko, V. L.; Mohn, P.; Schwarz, K.; Blaha, P.

1996-02-01

Employing a high-precision band structure method (FP LAPW - full potential linearized augmented plane wave) we calculate the total energy variation along the tetragonal distortion path connecting the body centred cubic (bcc) and the face centred cubic (fcc) structures. The total energy along this Bain transformation is calculated, varying c/a and volume, providing a first-principles energy surface which has two minima as a function of c/a. These are shallow and occur for the sp metals at the two cubic structures, while Ti (V) has a minimum at fcc (bcc) but a saddle point (i.e. a minimum in volume and a maximum with respect to c/a) at the other cubic structure. These features can be analysed in terms of an interplay between the Madelung contribution and the band energies. Our total energy results allow us to calculate the elastic constants 0953-8984/8/7/006/img1 and 0953-8984/8/7/006/img2 and to study the influence of pressure on the phase stability. These energy surfaces will be used in part II of this paper to investigate finite-temperature effects by mapping them to a Landau - Ginzburg expansion.

High-accuracy phase-field models for brittle fracture based on a new family of degradation functions

NASA Astrophysics Data System (ADS)

Sargado, Juan Michael; Keilegavlen, Eirik; Berre, Inga; Nordbotten, Jan Martin

2018-02-01

Phase-field approaches to fracture based on energy minimization principles have been rapidly gaining popularity in recent years, and are particularly well-suited for simulating crack initiation and growth in complex fracture networks. In the phase-field framework, the surface energy associated with crack formation is calculated by evaluating a functional defined in terms of a scalar order parameter and its gradients. These in turn describe the fractures in a diffuse sense following a prescribed regularization length scale. Imposing stationarity of the total energy leads to a coupled system of partial differential equations that enforce stress equilibrium and govern phase-field evolution. These equations are coupled through an energy degradation function that models the loss of stiffness in the bulk material as it undergoes damage. In the present work, we introduce a new parametric family of degradation functions aimed at increasing the accuracy of phase-field models in predicting critical loads associated with crack nucleation as well as the propagation of existing fractures. An additional goal is the preservation of linear elastic response in the bulk material prior to fracture. Through the analysis of several numerical examples, we demonstrate the superiority of the proposed family of functions to the classical quadratic degradation function that is used most often in the literature.

Bond Dissociation Energies of the Tungsten Fluorides and Their Singly-Charged Ions: A Density Functional Survey

NASA Technical Reports Server (NTRS)

Dyall, Kenneth G.; Arnold, James (Technical Monitor)

1999-01-01

The dissociation of WF6 and the related singly-charged cations and anions into the lower fluorides and fluorine atoms has been investigated theoretically using density functional theory (B3LYP) and relativistic effective core potentials, with estimates of spin-orbit effects included using a simple model. The inclusion of spin-orbit is essential for a correct description of the thermochemistry. The total atomization energy of the neutral and anionic WF6 is reproduced to within 25 kcal/mol, but comparison of individual bond dissociation energies with available experimental data shows discrepancies of up to 10 kcal/mol. The results are nevertheless useful to help resolve discrepancies in experimental data and provide estimates of missing data.

Measurement of νμ-induced charged-current neutral pion production cross sections on mineral oil at Eν∈0.5-2.0GeV

NASA Astrophysics Data System (ADS)

Aguilar-Arevalo, A. A.; Anderson, C. E.; Bazarko, A. O.; Brice, S. J.; Brown, B. C.; Bugel, L.; Cao, J.; Coney, L.; Conrad, J. M.; Cox, D. C.; Curioni, A.; Dharmapalan, R.; Djurcic, Z.; Finley, D. A.; Fleming, B. T.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Grange, J.; Green, C.; Green, J. A.; Hart, T. L.; Hawker, E.; Imlay, R.; Johnson, R. A.; Karagiorgi, G.; Kasper, P.; Katori, T.; Kobilarcik, T.; Kourbanis, I.; Koutsoliotas, S.; Laird, E. M.; Linden, S. K.; Link, J. M.; Liu, Y.; Liu, Y.; Louis, W. C.; Mahn, K. B. M.; Marsh, W.; Mauger, C.; McGary, V. T.; McGregor, G.; Metcalf, W.; Meyers, P. D.; Mills, F.; Mills, G. B.; Monroe, J.; Moore, C. D.; Mousseau, J.; Nelson, R. H.; Nienaber, P.; Nowak, J. A.; Osmanov, B.; Ouedraogo, S.; Patterson, R. B.; Pavlovic, Z.; Perevalov, D.; Polly, C. C.; Prebys, E.; Raaf, J. L.; Ray, H.; Roe, B. P.; Russell, A. D.; Sandberg, V.; Schirato, R.; Schmitz, D.; Shaevitz, M. H.; Shoemaker, F. C.; Smith, D.; Soderberg, M.; Sorel, M.; Spentzouris, P.; Spitz, J.; Stancu, I.; Stefanski, R. J.; Sung, M.; Tanaka, H. A.; Tayloe, R.; Tzanov, M.; van de Water, R. G.; Wascko, M. O.; White, D. H.; Wilking, M. J.; Yang, H. J.; Zeller, G. P.; Zimmerman, E. D.

2011-03-01

Using a custom 3-Čerenkov ring fitter, we report cross sections for νμ-induced charged-current single π0 production on mineral oil (CH2) from a sample of 5810 candidate events with 57% signal purity over an energy range of 0.5-2.0 GeV. This includes measurements of the absolute total cross section as a function of neutrino energy, and flux-averaged differential cross sections measured in terms of Q2, μ- kinematics, and π0 kinematics. The sample yields a flux-averaged total cross section of (9.2±0.3stat±1.5syst)×10-39cm2/CH2 at mean neutrino energy of 0.965 GeV.

Single crystal to polycrystal neutron transmission simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dessieux, Luc Lucius; Stoica, Alexandru Dan; Bingham, Philip R.

A collection of routines for calculation of the total cross section that determines the attenuation of neutrons by crystalline solids is presented. The total cross section is calculated semi-empirically as a function of crystal structure, neutron energy, temperature, and crystal orientation. The semi-empirical formula includes the contribution of parasitic Bragg scattering to the total cross section using both the crystal’s mosaic spread value and its orientation with respect to the neutron beam direction as parameters. These routines allow users to enter a distribution of crystal orientations for calculation of total cross sections of user defined powder or pseudo powder distributions,more » which enables simulation of non-uniformities such as texture and strain. In conclusion, the spectra for neutron transmission simulations in the neutron thermal energy range (2 meV–100 meV) are presented for single crystal and polycrystal samples and compared to measurements.« less

Single crystal to polycrystal neutron transmission simulation

DOE PAGES

Dessieux, Luc Lucius; Stoica, Alexandru Dan; Bingham, Philip R.

2018-02-02

A collection of routines for calculation of the total cross section that determines the attenuation of neutrons by crystalline solids is presented. The total cross section is calculated semi-empirically as a function of crystal structure, neutron energy, temperature, and crystal orientation. The semi-empirical formula includes the contribution of parasitic Bragg scattering to the total cross section using both the crystal’s mosaic spread value and its orientation with respect to the neutron beam direction as parameters. These routines allow users to enter a distribution of crystal orientations for calculation of total cross sections of user defined powder or pseudo powder distributions,more » which enables simulation of non-uniformities such as texture and strain. In conclusion, the spectra for neutron transmission simulations in the neutron thermal energy range (2 meV–100 meV) are presented for single crystal and polycrystal samples and compared to measurements.« less

Dirac-Kähler particle in Riemann spherical space: boson interpretation

NASA Astrophysics Data System (ADS)

Ishkhanyan, A. M.; Florea, O.; Ovsiyuk, E. M.; Red'kov, V. M.

2015-11-01

In the context of the composite boson interpretation, we construct the exact general solution of the Dirac--K\\"ahler equation for the case of the spherical Riemann space of constant positive curvature, for which due to the geometry itself one may expect to have a discrete energy spectrum. In the case of the minimal value of the total angular momentum, $j=0$, the radial equations are reduced to second-order ordinary differential equations, which are straightforwardly solved in terms of the hypergeometric functions. For non-zero values of the total angular momentum, however, the radial equations are reduced to a pair of complicated fourth-order differential equations. Employing the factorization approach, we derive the general solution of these equations involving four independent fundamental solutions written in terms of combinations of the hypergeometric functions. The corresponding discrete energy spectrum is then determined via termination of the involved hypergeometric series, resulting in quasi-polynomial wave-functions. The constructed solutions lead to notable observations when compared with those for the ordinary Dirac particle. The energy spectrum for the Dirac-K\\"ahler particle in spherical space is much more complicated. Its structure substantially differs from that for the Dirac particle since it consists of two paralleled energy level series each of which is twofold degenerate. Besides, none of the two separate series coincides with the series for the Dirac particle. Thus, the Dirac--K\\"ahler field cannot be interpreted as a system of four Dirac fermions. Additional arguments supporting this conclusion are discussed.

Challenges in Maintaining Emotion Regulation in a Sleep and Energy Deprived State Induced by the 4800Km Ultra-Endurance Bicycle Race; The Race Across AMerica (RAAM).

PubMed

Lahart, Ian M; Lane, Andrew M; Hulton, Andrew; Williams, Karen; Godfrey, Richard; Pedlar, Charles; Wilson, Mathew G; Whyte, Gregory P

2013-01-01

Multiday ultra-endurance races present athletes with a significant number of physiological and psychological challenges. We examined emotions, the perceived functionality (optimal-dysfunctional) of emotions, strategies to regulate emotions, sleep quality, and energy intake-expenditure in a four-man team participating in the Race Across AMerica (RAAM); a 4856km continuous cycle race. Cyclists reported experiencing an optimal emotional state for less than 50% of total competition, with emotional states differing significantly between each cyclist over time. Coupled with this emotional disturbance, each cyclist experienced progressively worsening sleep deprivation and daily negative energy balances throughout the RAAM. Cyclists managed less than one hour of continuous sleep per sleep episode, high sleep latency and high percentage moving time. Of note, actual sleep and sleep efficiency were better maintained during longer rest periods, highlighting the importance of a race strategy that seeks to optimise the balance between average cycling velocity and sleep time. Our data suggests that future RAAM cyclists and crew should: 1) identify beliefs on the perceived functionality of emotions in relation to best (functional-optimal) and worst (dysfunctional) performance as the starting point to intervention work; 2) create a plan for support sufficient sleep and recovery; 3) create nutritional strategies that maintain energy intake and thus reduce energy deficits; and 4) prepare for the deleterious effects of sleep deprivation so that they are able to appropriately respond to unexpected stressors and foster functional working interpersonal relationships. Key PointsCompleting the Race Across AMerica (RAAM); a 4856km continuous cycle race associated with sleep disturbance, an energy-deficient state, and experiencing intense unwanted emotions.Cyclists reported experiencing an optimal emotional state for less than 50% of total competition and actual sleep and sleep efficiency was better maintained during longer rest periods.We suggest that future RAAM cyclists and crew should:Identify individual beliefs on the perceived functionality of emotional states in relation to best (optimal) and worst (dysfunctional) performance as the starting point to identifying if emotion regulation strategies should be initiated.Plan for enhanced sleep and recovery not just plan and train for maintaining a high average velocity;Create nutritional strategies that maintain energy intake and thus reduce energy deficits;Psychologically prepare cyclists and crew for the deleterious effects of sleep deprivation so that they both are able to appropriately respond to unexpected stressors and foster functional interpersonal working relationships.

Investigation of total cross sections for reactions induced by {sup 6}He interaction with silicon nuclei at energies between 5 and 50 MeV/A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kabdrakhimova, G. D., E-mail: gaukharkd@gmail.com; Sobolev, Yu. G.; Kuhtina, I. N.

2017-01-15

Experimental excitation functions in terms of the total cross sections for {sup 6}He + Si nuclear reactions are analyzed in the energy range between 5 and 50 MeV/A, and a brief survey of the procedures used to obtain experimental data is given. Particular attention is given to describing experiments performed in beams of radioactive nuclei from the accelerators of the Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (JINR, Dubna). The experimental data in question are analyzed on the basis of a semimicroscopic optical model.

Bound states in string nets

NASA Astrophysics Data System (ADS)

Schulz, Marc Daniel; Dusuel, Sébastien; Vidal, Julien

2016-11-01

We discuss the emergence of bound states in the low-energy spectrum of the string-net Hamiltonian in the presence of a string tension. In the ladder geometry, we show that a single bound state arises either for a finite tension or in the zero-tension limit depending on the theory considered. In the latter case, we perturbatively compute the binding energy as a function of the total quantum dimension. We also address this issue in the honeycomb lattice where the number of bound states in the topological phase depends on the total quantum dimension. Finally, the internal structure of these bound states is analyzed in the zero-tension limit.

Augmented potential, energy densities, and virial relations in the weak- and strong-interaction limits of DFT

NASA Astrophysics Data System (ADS)

Vuckovic, Stefan; Levy, Mel; Gori-Giorgi, Paola

2017-12-01

The augmented potential introduced by Levy and Zahariev [Phys. Rev. Lett. 113, 113002 (2014)] is shifted with respect to the standard exchange-correlation potential of the Kohn-Sham density functional theory by a density-dependent constant that makes the total energy become equal to the sum of the occupied orbital energies. In this work, we analyze several features of this approach, focusing on the limit of infinite coupling strength and studying the shift and the corresponding energy density at different correlation regimes. We present and discuss coordinate scaling properties of the augmented potential, study its connection to the response potential, and use the shift to analyze the classical jellium and uniform gas models. We also study other definitions of the energy densities in relation to the functional construction by local interpolations along the adiabatic connection. Our findings indicate that the energy density that is defined in terms of the electrostatic potential of the exchange-correlation hole is particularly well suited for this purpose.

Image charge effects on electron capture by dust grains in dusty plasmas.

PubMed

Jung, Y D; Tawara, H

2001-07-01

Electron-capture processes by negatively charged dust grains from hydrogenic ions in dusty plasmas are investigated in accordance with the classical Bohr-Lindhard model. The attractive interaction between the electron in a hydrogenic ion and its own image charge inside the dust grain is included to obtain the total interaction energy between the electron and the dust grain. The electron-capture radius is determined by the total interaction energy and the kinetic energy of the released electron in the frame of the projectile dust grain. The classical straight-line trajectory approximation is applied to the motion of the ion in order to visualize the electron-capture cross section as a function of the impact parameter, kinetic energy of the projectile ion, and dust charge. It is found that the image charge inside the dust grain plays a significant role in the electron-capture process near the surface of the dust grain. The electron-capture cross section is found to be quite sensitive to the collision energy and dust charge.

A simple but fully nonlocal correction to the random phase approximation

NASA Astrophysics Data System (ADS)

Ruzsinszky, Adrienn; Perdew, John P.; Csonka, Gábor I.

2011-03-01

The random phase approximation (RPA) stands on the top rung of the ladder of ground-state density functional approximations. The simple or direct RPA has been found to predict accurately many isoelectronic energy differences. A nonempirical local or semilocal correction to this direct RPA leaves isoelectronic energy differences almost unchanged, while improving total energies, ionization energies, etc., but fails to correct the RPA underestimation of molecular atomization energies. Direct RPA and its semilocal correction may miss part of the middle-range multicenter nonlocality of the correlation energy in a molecule. Here we propose a fully nonlocal, hybrid-functional-like addition to the semilocal correction. The added full nonlocality is important in molecules, but not in atoms. Under uniform-density scaling, this fully nonlocal correction scales like the second-order-exchange contribution to the correlation energy, an important part of the correction to direct RPA, and like the semilocal correction itself. For the atomization energies of ten molecules, and with the help of one fit parameter, it performs much better than the elaborate second-order screened exchange correction.

Role of Ongoing, Intrinsic Activity of Neuronal Populations for Quantitative Neuroimaging of Functional Magnetic Resonance Imaging–Based Networks

PubMed Central

Herman, Peter; Sanganahalli, Basavaraju G.; Coman, Daniel; Blumenfeld, Hal; Rothman, Douglas L.

2011-01-01

Abstract A primary objective in neuroscience is to determine how neuronal populations process information within networks. In humans and animal models, functional magnetic resonance imaging (fMRI) is gaining increasing popularity for network mapping. Although neuroimaging with fMRI—conducted with or without tasks—is actively discovering new brain networks, current fMRI data analysis schemes disregard the importance of the total neuronal activity in a region. In task fMRI experiments, the baseline is differenced away to disclose areas of small evoked changes in the blood oxygenation level-dependent (BOLD) signal. In resting-state fMRI experiments, the spotlight is on regions revealed by correlations of tiny fluctuations in the baseline (or spontaneous) BOLD signal. Interpretation of fMRI-based networks is obscured further, because the BOLD signal indirectly reflects neuronal activity, and difference/correlation maps are thresholded. Since the small changes of BOLD signal typically observed in cognitive fMRI experiments represent a minimal fraction of the total energy/activity in a given area, the relevance of fMRI-based networks is uncertain, because the majority of neuronal energy/activity is ignored. Thus, another alternative for quantitative neuroimaging of fMRI-based networks is a perspective in which the activity of a neuronal population is accounted for by the demanded oxidative energy (CMRO2). In this article, we argue that network mapping can be improved by including neuronal energy/activity of both the information about baseline and small differences/fluctuations of BOLD signal. Thus, total energy/activity information can be obtained through use of calibrated fMRI to quantify differences of ΔCMRO2 and through resting-state positron emission tomography/magnetic resonance spectroscopy measurements for average CMRO2. PMID:22433047

Modeling the energetic and exergetic self-sustainability of societies with different structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sciubba, E.

1995-06-01

The paper examines global energy and exergy flows in various models of organized human societies: from primitive tribal organizations to teocratic/aristocratic societies, to the present industrial (and post-industrial) society, to possible future highly robotized or central control social organizations. The analysis focuses on the very general chain of technological processes connected to the extraction, conversion, distribution and final use of the real energetic content of natural resources (i.e., their exergy): the biological food chain is also considered, albeit in a very simplified and humankind sense. It is argued that, to sustain this chain of processes, it is necessary to usemore » a substantial portion of the final-use energy flow, and to employ a large portion of the total work force sustained by this end-use energy. It is shown that if these quantities can be related to the total exergy flow rate (from the source) and to the total available work force, then this functional relationship takes different forms in different types of society. The procedure is very general: each type of societal organization is reduced to a simple model for which energy and exergy flow diagrams are calculated, under certain well-defined assumptions, which restrain both the exchanges among the functional groups which constitute the model, and the exchanges with the environment. The results can be quantified using some assumptions/projections about energy consumption levels for different stages of technological development which are available in the literature; the procedure is applied to some models of primitive and pre-industrial societies, to the present industrial/post-industrial society, and to a hypothetical model of a future, high-technology society.« less

Role of an electronic armband in motor function monitoring in patients with Parkinson's disease.

PubMed

Cereda, Emanuele; Pezzoli, Gianni; Barichella, Michela

2010-02-01

Levodopa replacement still is the gold standard for the management of Parkinson's disease (PD). Long-term treatment with levodopa is frequently associated with motor fluctuations. A low-protein (LP) dietary regimen has proved to be effective in reducing this adverse effect, but has been associated with weight loss, probably due to increased energy expenditure. A new wearable device (SenseWear Armband [SWA]) has recently been introduced into clinical practice. It is designed to monitor physical activity continuously and provide estimates of energy consumption. We assessed its role in measuring the effects of dietary regimens on motor function in PD. Six patients with levodopa-treated PD and motor fluctuations were asked to follow a balanced diet (protein 1g x kg(-1) x d(-1)) for 7 d and then to cross over to a isocaloric LP (protein 0.7 g x kg(-1) x d(-1)) dietary regimen. Total daily energy expenditures, physical activity, number of steps, and metabolic rate were assessed continuously (14 d) by the SWA. Motor control was evaluated by daily diaries. The SWA proved that, during the LP diet, mean total daily energy expenditure was higher (P<0.05) and so were physical activity (P=0.05) and average metabolic rate (P=0.01), despite no change in the number of steps. The duration of periods with dyskinesias was also increased (P<0.05). These data support the role of upper-extremity involuntary movements in increasing total daily energy expenditure during an LP diet. The SWA may help in monitoring patients with PD because it can assist in evaluating motor response to treatment and changes in physical activity and daily calorie needs. 2010 Elsevier Inc. All rights reserved.

Exploring the effect of oxygen-containing functional groups on the water-holding capacity of lignite.

PubMed

Liu, Jie; Jiang, Xiangang; Cao, Yu; Zhang, Chen; Zhao, Guangyao; Zhao, Maoshuang; Feng, Li

2018-05-07

Graphene oxide with different degrees of oxidation was prepared and selected as a model compound of lignite to study quantitatively, using both experiment and theoretical calculation methods, the effect on water-holding capacity of oxygen-containing functional groups. The experimental results showed that graphite can be oxidized, and forms epoxy groups most easily, followed by hydroxyl and carboxyl groups. The prepared graphene oxide forms a membrane-state as a single layer structure, with an irregular surface. The water-holding capacity of lignite increased with the content of oxygen-containing functional groups. The influence on the configuration of water molecule clusters and binding energy of water molecules of different oxygen-containing functional groups was calculated by density functional theory. The calculation results indicated that the configuration of water molecule clusters was totally changed by oxygen-containing functional groups. The order of binding energy produced by oxygen-containing functional groups and water molecules was as follows: carboxyl > edge phenol hydroxyl >epoxy group. Finally, it can be concluded that the potential to form more hydrogen bonds is the key factor influencing the interaction energy between model compounds and water molecules.

Comparative analysis of proton- and neutron-halo breakups

NASA Astrophysics Data System (ADS)

Mukeru, B.

2018-06-01

A detailed analysis of the proton- and neutron-halo breakup cross sections is presented. Larger neutron-halo breakup cross sections than proton-halo breakup cross sections are obtained. This is found to be mainly due to the projectile structure, namely the ground state wave function and the dipole electric response function. It is also found that the continuum–continuum couplings are stronger in the proton-halo breakup than in the neutron-halo breakup. The increase of proton- and neutron-halo ground state separation energy slightly strengthens these couplings in the proton- and neutron-halo total and nuclear breakups, while they are weakened in the proton- and neutron-halo Coulomb breakups. The Coulomb-nuclear interference remains strongly destructive in both proton- and neutron-halo breakups and this is independent of the ground state separation energy. The results also show that the increase of the neutron-halo ground state separation energy decreases significantly the agreement between the proton- and neutron-halo breakup cross sections, both qualitatively and quantitatively. It is obtained that when the proton-halo ground state separation energy is increased by a factor of 4.380, the proton-halo breakup cross section is reduced by a factor of 4.392, indicating a clear proportionality. However, when the neutron-halo ground state separation energy is increased by the same factor, the neutron-halo total breakup cross section is reduced by a factor of 8.522.

Measurements of the total cross section of natBe with thermal neutrons from a photo-neutron source

NASA Astrophysics Data System (ADS)

Liu, L. X.; Wang, H. W.; Ma, Y. G.; Cao, X. G.; Cai, X. Z.; Chen, J. G.; Zhang, G. L.; Han, J. L.; Zhang, G. Q.; Hu, J. F.; Wang, X. H.; Li, W. J.; Yan, Z.; Fu, H. J.

2017-11-01

The total neutron cross sections of natural beryllium in the neutron energy region of 0.007 to 0.1 eV were measured by using a time-of-flight (TOF) technique at the Shanghai Institute of Applied Physics (SINAP). The low energy neutrons were obtained by moderating the high energy neutrons from a pulsed photo-neutron source generated from a 16 MeV electron linac. The time dependent neutron background component was determined by employing the 12.8 cm boron-loaded polyethylene (PEB) (5% w.t.) to block neutron TOF path and using the Monte Carlo simulation methods. The present data was compared with the fold Harvey data with the response function of the photo-neutron source (PNS, phase-1). The present measurement of total cross section of natBe for thermal neutrons based on PNS has been developed for the acquisition of nuclear data needed for the Thorium Molten Salt Reactor (TMSR).

Energy efficiency in new museum build: THEpUBLIC

NASA Astrophysics Data System (ADS)

Battle, G.; Yuen, C. H. N.; Zanchetta, M.; D'Cruz, P.

2006-12-01

The project MUSEUMS, awarded the Thermie Grant from the European Commission, has applied and tested new and innovative technologies for optimizing energy efficiency and sustainability in nine retrofitted and new museum buildings in Europe. The project will significantly contribute to the acceptance of innovative and renewable technologies in public buildings by demonstrating that retrofitted and new museum buildings can fully meet architectural, functional, comfort, control and safety requirements as well as achieve total energy savings of over 35% and reduce CO2 emissions by over 50%. THEpUBLIC will be a stunning and modern flagship building containing six storeys, with a total area of 11,000Âm2 of galleries for exhibitions, digital art and hands-on displays. In addition, there will be workspaces, creative spaces, retail opportunities, restaurant facilities, public areas, conference rooms and other multi-function spaces. Initiated by Jubilee Arts, the THEpUBLIC, designed by Alsop Architects, will introduce and engage its 400,000 expected visitors in the principles of energy and the environment through a display of art, education, technology and entertainment in the centre of West Bromwich, Sandwell. It will serve as a catalyst for urban regeneration within Sandwell.Battle McCarthy's key environmental design solutions for THEpUBLIC include natural daylighting, mixed-mode ventilation system with operable windows, low energy and maintenance cost systems, potential for integrating renewable energy collection systems, borehole water systems for cooling and water supply, an intelligent facade system with external shading and natural ventilation and night cooling systems.

Index of mechanical work in gait of children with cerebral palsy.

PubMed

Dziuba, Alicja Katarzyna; Tylkowska, Małgorzata; Jaroszczuk, Sebastian

2014-01-01

The pathological gait of children with cerebral palsy involves higher mechanical work, which limits their ability to function properly in society. Mechanical work is directly related to walking speed and, although a number of studies have been carried out in this field, few of them analysed the effect of the speed. The study aimed to develop standards for mechanical work during gait of children with cerebral palsy depending on the walking speed. The study covered 18 children with cerebral palsy and 14 healthy children. The BTS Smart software and the author's software were used to evaluate mechanical work, kinetic, potential and rotational energy connected with motion of the children body during walk. Compared to healthy subjects, mechanical work in children with cerebral palsy increases with the degree of disability. It can be expressed as a linear function of walking speed and shows strong and statistically significant correlations with walking gait. A negative statistically significant correlation between the degree of disability and walking speed can be observed. The highest contribution to the total mechanical energy during gait is from mechanical energy of the feet. Instantaneous value of rotational energy is 700 times lower than the instantaneous mechanical energy. An increase in walking speed causes the increase in the effect of the index of kinetic energy on total mechanical work. The method described can provide an objective supplementation for doctors and physical therapists to perform a simple and immediate diagnosis without much technical knowledge.

Calculation of Cardiac Kinetic Energy Index from PET images.

PubMed

Sims, John; Oliveira, Marco Antônio; Meneghetti, José Claudio; Gutierrez, Marco Antônio

2015-01-01

Cardiac function can be assessed from displacement measurements in imaging modalities from nuclear medicine Using positron emission tomography (PET) image sequences with Rubidium-82, we propose and estimate the total Kinetic Energy Index (KEf) obtained from the velocity field, which was calculated using 3D optical flow(OF) methods applied over the temporal image sequence. However, it was found that the brightness of the image varied unexpectedly between frames, violating the constant brightness assumption of the OF method and causing large errors in estimating the velocity field. Therefore total brightness was equalized across image frames and the adjusted configuration tested with rest perfusion images acquired from individuals with normal (n=30) and low (n=33) cardiac function. For these images KEf was calculated as 0.5731±0.0899 and 0.3812±0.1146 for individuals with normal and low cardiac function respectively. The ability of KEf to properly classify patients into the two groups was tested with a ROC analysis, with area under the curve estimated as 0.906. To our knowledge this is the first time that KEf has been applied to PET images.

Field emission energy distributions of hydrogen and deuterium on the /100/ and /110/ planes of tungsten.

NASA Technical Reports Server (NTRS)

Plummer, E. W.; Bell, A. E.

1972-01-01

Total energy distributions of field emitted electrons from the tungsten (110) and (100) planes as a function of coverage by hydrogen and deuterium have been recorded utilizing a spherical deflection energy analyzer. The elastic tunneling resonance spectrum gives a plot of the 'local density of states' in the adsorbate. The inelastic tunneling spectrum reveals those discrete excitation energies available in the adsorbate-substrate complex. These spectroscopic data have been used to infer the chemical nature of the binding states which have been observed in the flash desorption spectrum of hydrogen from tungsten.

Chia Oil Extraction Coproduct as a Potential New Ingredient for the Food Industry: Chemical, Physicochemical, Techno-Functional and Antioxidant Properties.

PubMed

Fernández-López, Juana; Lucas-González, Raquel; Viuda-Martos, Manuel; Sayas-Barberá, Estrella; Pérez-Alvarez, José Angel

2018-06-01

The aim of this work was to characterize the coproduct obtained from chia oil production (cold-pressing) with a view to its possible application in new food product development. For this characterization, the following determinations were made: proximate composition, physicochemical analysis, techno-functional properties, total phenolic and flavonoid content, polyphenolic profile and antioxidant capacity (using four different methods). Chia coproduct showed significantly higher levels of proteins and total dietary fiber and lower levels of fats than chia seeds, pointing to the promising nature of this coproduct as an ingredient of food formulations since it remains a source of high biological value proteins and total dietary fiber (as chia seeds themselves) but with a lower energy value. This chia coproduct presents similar techno-functional properties to the original chia seeds and significantly higher levels of polyphenolic compounds and, consequently, higher antioxidant activity.

Differential geometry based solvation model I: Eulerian formulation

NASA Astrophysics Data System (ADS)

Chen, Zhan; Baker, Nathan A.; Wei, G. W.

2010-11-01

This paper presents a differential geometry based model for the analysis and computation of the equilibrium property of solvation. Differential geometry theory of surfaces is utilized to define and construct smooth interfaces with good stability and differentiability for use in characterizing the solvent-solute boundaries and in generating continuous dielectric functions across the computational domain. A total free energy functional is constructed to couple polar and nonpolar contributions to the solvation process. Geometric measure theory is employed to rigorously convert a Lagrangian formulation of the surface energy into an Eulerian formulation so as to bring all energy terms into an equal footing. By optimizing the total free energy functional, we derive coupled generalized Poisson-Boltzmann equation (GPBE) and generalized geometric flow equation (GGFE) for the electrostatic potential and the construction of realistic solvent-solute boundaries, respectively. By solving the coupled GPBE and GGFE, we obtain the electrostatic potential, the solvent-solute boundary profile, and the smooth dielectric function, and thereby improve the accuracy and stability of implicit solvation calculations. We also design efficient second-order numerical schemes for the solution of the GPBE and GGFE. Matrix resulted from the discretization of the GPBE is accelerated with appropriate preconditioners. An alternative direct implicit (ADI) scheme is designed to improve the stability of solving the GGFE. Two iterative approaches are designed to solve the coupled system of nonlinear partial differential equations. Extensive numerical experiments are designed to validate the present theoretical model, test computational methods, and optimize numerical algorithms. Example solvation analysis of both small compounds and proteins are carried out to further demonstrate the accuracy, stability, efficiency and robustness of the present new model and numerical approaches. Comparison is given to both experimental and theoretical results in the literature.

Differential geometry based solvation model I: Eulerian formulation

PubMed Central

Chen, Zhan; Baker, Nathan A.; Wei, G. W.

2010-01-01

This paper presents a differential geometry based model for the analysis and computation of the equilibrium property of solvation. Differential geometry theory of surfaces is utilized to define and construct smooth interfaces with good stability and differentiability for use in characterizing the solvent-solute boundaries and in generating continuous dielectric functions across the computational domain. A total free energy functional is constructed to couple polar and nonpolar contributions to the salvation process. Geometric measure theory is employed to rigorously convert a Lagrangian formulation of the surface energy into an Eulerian formulation so as to bring all energy terms into an equal footing. By minimizing the total free energy functional, we derive coupled generalized Poisson-Boltzmann equation (GPBE) and generalized geometric flow equation (GGFE) for the electrostatic potential and the construction of realistic solvent-solute boundaries, respectively. By solving the coupled GPBE and GGFE, we obtain the electrostatic potential, the solvent-solute boundary profile, and the smooth dielectric function, and thereby improve the accuracy and stability of implicit solvation calculations. We also design efficient second order numerical schemes for the solution of the GPBE and GGFE. Matrix resulted from the discretization of the GPBE is accelerated with appropriate preconditioners. An alternative direct implicit (ADI) scheme is designed to improve the stability of solving the GGFE. Two iterative approaches are designed to solve the coupled system of nonlinear partial differential equations. Extensive numerical experiments are designed to validate the present theoretical model, test computational methods, and optimize numerical algorithms. Example solvation analysis of both small compounds and proteins are carried out to further demonstrate the accuracy, stability, efficiency and robustness of the present new model and numerical approaches. Comparison is given to both experimental and theoretical results in the literature. PMID:20938489

Sleep fragmentation alters brain energy metabolism without modifying hippocampal electrophysiological response to novelty exposure.

PubMed

Baud, Maxime O; Parafita, Julia; Nguyen, Audrey; Magistretti, Pierre J; Petit, Jean-Marie

2016-10-01

Sleep is viewed as a fundamental restorative function of the brain, but its specific role in neural energy budget remains poorly understood. Sleep deprivation dampens brain energy metabolism and impairs cognitive functions. Intriguingly, sleep fragmentation, despite normal total sleep duration, has a similar cognitive impact, and in this paper we ask the question of whether it may also impair brain energy metabolism. To this end, we used a recently developed mouse model of 2 weeks of sleep fragmentation and measured 2-deoxy-glucose uptake and glycogen, glucose and lactate concentration in different brain regions. In order to homogenize mice behaviour during metabolic measurements, we exposed them to a novel environment for 1 h. Using an intra-hippocampal electrode, we first showed that hippocampal electroencephalograph (EEG) response to exploration was unaltered by 1 or 14 days of sleep fragmentation. However, after 14 days, sleep fragmented mice exhibited a lower uptake of 2-deoxy-glucose in cortex and hippocampus and lower cortical lactate levels than control mice. Our results suggest that long-term sleep fragmentation impaired brain metabolism to a similar extent as total sleep deprivation without affecting the neuronal responsiveness of hippocampus to a novel environment. © 2016 European Sleep Research Society.

Track structure in radiation biology: theory and applications.

PubMed

Nikjoo, H; Uehara, S; Wilson, W E; Hoshi, M; Goodhead, D T

1998-04-01

A brief review is presented of the basic concepts in track structure and the relative merit of various theoretical approaches adopted in Monte-Carlo track-structure codes are examined. In the second part of the paper, a formal cluster analysis is introduced to calculate cluster-distance distributions. Total experimental ionization cross-sections were least-square fitted and compared with the calculation by various theoretical methods. Monte-Carlo track-structure code Kurbuc was used to examine and compare the spectrum of the secondary electrons generated by using functions given by Born-Bethe, Jain-Khare, Gryzinsky, Kim-Rudd, Mott and Vriens' theories. The cluster analysis in track structure was carried out using the k-means method and Hartigan algorithm. Data are presented on experimental and calculated total ionization cross-sections: inverse mean free path (IMFP) as a function of electron energy used in Monte-Carlo track-structure codes; the spectrum of secondary electrons generated by different functions for 500 eV primary electrons; cluster analysis for 4 MeV and 20 MeV alpha-particles in terms of the frequency of total cluster energy to the root-mean-square (rms) radius of the cluster and differential distance distributions for a pair of clusters; and finally relative frequency distribution for energy deposited in DNA, single-strand break and double-strand breaks for 10MeV/u protons, alpha-particles and carbon ions. There are a number of Monte-Carlo track-structure codes that have been developed independently and the bench-marking presented in this paper allows a better choice of the theoretical method adopted in a track-structure code to be made. A systematic bench-marking of cross-sections and spectra of the secondary electrons shows differences between the codes at atomic level, but such differences are not significant in biophysical modelling at the macromolecular level. Clustered-damage evaluation shows: that a substantial proportion of dose ( 30%) is deposited by low-energy electrons; the majority of DNA damage lesions are of simple type; the complexity of damage increases with increased LET, while the total yield of strand breaks remains constant; and at high LET values nearly 70% of all double-strand breaks are of complex type.

Total Water Intake from Beverages and Foods Is Associated with Energy Intake and Eating Behaviors in Korean Adults.

PubMed

Lee, Kyung Won; Shin, Dayeon; Song, Won O

2016-10-04

Water is essential for the proper functioning of the body. Even though a recommendation exists for adequate water intake for Koreans, studies identifying actual water intake from all beverages and foods consumed daily in the Korean population are limited. Thus, we estimated total water intake from both beverages and foods and its association with energy intake and eating behaviors in Korean adults. We used a nationally representative sample of 25,122 Korean adults aged ≥19 years, from the Korean National Health and Nutrition Examination Survey 2008-2012. We performed multiple regression analyses, adjusting for sociodemographic and health-related variables to investigate the contribution of overall energy and dietary intakes and eating behaviors to total water intake. The mean total water intake excluding plain water was 1071 g (398 g from beverages and 673 g from foods) and the estimated plain water intake was 1.3 L. Among Korean adults, 82% consumed beverages (excluding plain water) and these beverages contributed to 10% of daily energy intake and 32% of total water intake from beverages and foods. For every 100 kcal/day in energy intake, water intake consumed through beverages and foods increased by 18 g and 31 g, respectively. Water intake from beverages and foods was positively associated with energy from fat and dietary calcium, but inversely associated with energy density and energy from carbohydrates. When there was a 5% increase in energy intake from snacks and eating outside the home, there was an increase in water intake from beverages of 13 g and 2 g, respectively. Increased daily energy intake, the number of eating episodes, and energy intake from snacks and eating outside the home predicted higher water intake from beverages and foods. Our results provide evidence suggesting that various factors, including sociodemographic status, dietary intakes, and eating behaviors, could be important contributors to the water intake of Korean adults. Findings from this cross-sectional analysis may provide insight into strategies for promoting adequate water intake among Koreans.

Total Water Intake from Beverages and Foods Is Associated with Energy Intake and Eating Behaviors in Korean Adults

PubMed Central

Lee, Kyung Won; Shin, Dayeon; Song, Won O.

2016-01-01

Water is essential for the proper functioning of the body. Even though a recommendation exists for adequate water intake for Koreans, studies identifying actual water intake from all beverages and foods consumed daily in the Korean population are limited. Thus, we estimated total water intake from both beverages and foods and its association with energy intake and eating behaviors in Korean adults. We used a nationally representative sample of 25,122 Korean adults aged ≥19 years, from the Korean National Health and Nutrition Examination Survey 2008–2012. We performed multiple regression analyses, adjusting for sociodemographic and health-related variables to investigate the contribution of overall energy and dietary intakes and eating behaviors to total water intake. The mean total water intake excluding plain water was 1071 g (398 g from beverages and 673 g from foods) and the estimated plain water intake was 1.3 L. Among Korean adults, 82% consumed beverages (excluding plain water) and these beverages contributed to 10% of daily energy intake and 32% of total water intake from beverages and foods. For every 100 kcal/day in energy intake, water intake consumed through beverages and foods increased by 18 g and 31 g, respectively. Water intake from beverages and foods was positively associated with energy from fat and dietary calcium, but inversely associated with energy density and energy from carbohydrates. When there was a 5% increase in energy intake from snacks and eating outside the home, there was an increase in water intake from beverages of 13 g and 2 g, respectively. Increased daily energy intake, the number of eating episodes, and energy intake from snacks and eating outside the home predicted higher water intake from beverages and foods. Our results provide evidence suggesting that various factors, including sociodemographic status, dietary intakes, and eating behaviors, could be important contributors to the water intake of Korean adults. Findings from this cross-sectional analysis may provide insight into strategies for promoting adequate water intake among Koreans. PMID:27782040

Accurate electronic and chemical properties of 3d transition metal oxides using a calculated linear response U and a DFT + U(V) method.

PubMed

Xu, Zhongnan; Joshi, Yogesh V; Raman, Sumathy; Kitchin, John R

2015-04-14

We validate the usage of the calculated, linear response Hubbard U for evaluating accurate electronic and chemical properties of bulk 3d transition metal oxides. We find calculated values of U lead to improved band gaps. For the evaluation of accurate reaction energies, we first identify and eliminate contributions to the reaction energies of bulk systems due only to changes in U and construct a thermodynamic cycle that references the total energies of unique U systems to a common point using a DFT + U(V) method, which we recast from a recently introduced DFT + U(R) method for molecular systems. We then introduce a semi-empirical method based on weighted DFT/DFT + U cohesive energies to calculate bulk oxidation energies of transition metal oxides using density functional theory and linear response calculated U values. We validate this method by calculating 14 reactions energies involving V, Cr, Mn, Fe, and Co oxides. We find up to an 85% reduction of the mean average error (MAE) compared to energies calculated with the Perdew-Burke-Ernzerhof functional. When our method is compared with DFT + U with empirically derived U values and the HSE06 hybrid functional, we find up to 65% and 39% reductions in the MAE, respectively.

The Self-Association of Graphane Is Driven by London Dispersion and Enhanced Orbital Interactions.

PubMed

Wang, Changwei; Mo, Yirong; Wagner, J Philipp; Schreiner, Peter R; Jemmis, Eluvathingal D; Danovich, David; Shaik, Sason

2015-04-14

We investigated the nature of the cohesive energy between graphane sheets via multiple CH···HC interactions, using density functional theory (DFT) including dispersion correction (Grimme's D3 approach) computations of [n]graphane σ dimers (n = 6-73). For comparison, we also evaluated the binding between graphene sheets that display prototypical π/π interactions. The results were analyzed using the block-localized wave function (BLW) method, which is a variant of ab initio valence bond (VB) theory. BLW interprets the intermolecular interactions in terms of frozen interaction energy (ΔE(F)) composed of electrostatic and Pauli repulsion interactions, polarization (ΔE(pol)), charge-transfer interaction (ΔE(CT)), and dispersion effects (ΔE(disp)). The BLW analysis reveals that the cohesive energy between graphane sheets is dominated by two stabilizing effects, namely intermolecular London dispersion and two-way charge transfer energy due to the σ(CH) → σ*(HC) interactions. The shift of the electron density around the nonpolar covalent C-H bonds involved in the intermolecular interaction decreases the C-H bond lengths uniformly by 0.001 Å. The ΔE(CT) term, which accounts for ∼15% of the total binding energy, results in the accumulation of electron density in the interface area between two layers. This accumulated electron density thus acts as an electronic "glue" for the graphane layers and constitutes an important driving force in the self-association and stability of graphane under ambient conditions. Similarly, the "double faced adhesive tape" style of charge transfer interactions was also observed among graphene sheets in which it accounts for ∼18% of the total binding energy. The binding energy between graphane sheets is additive and can be expressed as a sum of CH···HC interactions, or as a function of the number of C-H bonds.

Partial-wave analysis for positronium-xenon collisions in the ultralow-energy region

NASA Astrophysics Data System (ADS)

Shibuya, Kengo; Saito, Haruo

2018-05-01

We propose a method to convert measured positronium annihilation rates in gaseous xenon into total and differential cross sections of positronium-xenon collisions in an ultralow-energy region of less than 80 meV where their experimental determinations as functions of the positronium kinetic energy are extremely difficult. This method makes it possible to determine not only the s -wave collisional parameters but also the p -wave and d -wave parameters. We have found a small positive value of the scattering length, A0=2.06 ±0.10 a0 , which indicates that the positronium-xenon interaction in this energy region is repulsive and suggests that it is dominated by the scattering amplitude of the positron rather than that of the electron. An extrapolation of the analytical result into the experimentally inaccessible energy regions from 80 meV to 1.0 eV indicates that there should not be a Ramsauer-Townsend minimum but rather a peak in the total cross section at an energy of approximately 0.4 eV.

Charged-particle pseudorapidity distributions in Au+Au collisions at sNN=62.4 GeV

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Halliwell, C.; Hamblen, J.; Hauer, M.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Seals, H.; Sedykh, I.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G. J. Van; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.

2006-08-01

The charged-particle pseudorapidity density for Au+Au collisions at sNN=62.4 GeV has been measured over a wide range of impact parameters and compared to results obtained at other energies. As a function of collision energy, the pseudorapidity distribution grows systematically both in height and width. The midrapidity density is found to grow approximately logarithmically between BNL Alternating Gradient Synchrotron (AGS) energies and the top BNL Relativistic Heavy Ion Collider (RHIC) energy. There is also an approximate factorization of the centrality and energy dependence of the midrapidity yields. The new results at sNN=62.4 GeV confirm the previously observed phenomenon of “extended longitudinal scaling” in the pseudorapidity distributions when viewed in the rest frame of one of the colliding nuclei. It is also found that the evolution of the shape of the distribution with centrality is energy independent, when viewed in this reference frame. As a function of centrality, the total charged particle multiplicity scales linearly with the number of participant pairs as it was observed at other energies.

The electronic and optical properties of Cs adsorbed GaAs nanowires via first-principles study

NASA Astrophysics Data System (ADS)

Diao, Yu; Liu, Lei; Xia, Sihao; Feng, Shu; Lu, Feifei

2018-07-01

In this study, we investigate the Cs adsorption mechanism on (110) surface of zinc-blende GaAs nanowire. The adsorption energy, work function, dipole moment, geometric structure, Mulliken charge distribution, charge transfer index, band structures, density of state and optical properties of Cs adsorption structures are calculated utilizing first-principles method based on density function theory. Total-energy calculations show that all the adsorption energies are negative, indicating that Cs adsorption process is exothermic and Cs covered GaAs nanowires are stable. The work function of nanowire surface has an obvious decrease after Cs adsorption. Besides, the ionization of nanowire surface is enhanced as well. More importantly, Cs adsorption contributes to a lower side shift of bands near Fermi level, and the corresponding band gap disappears. Additionally, the absorption peak and energy loss function after Cs adsorption are far higher than those before adsorption, implying better light absorption characteristic of nanowire surface after Cs adsorption. These theoretical calculations can directly guide the Cs activation experiment for negative electron affinity GaAs nanowire, and also lay a foundation for the further study of Cs/O co-adsorption on the nanowire surface.

A study of photon interaction in some building materials: High-volume admixture of blast furnace slag into Portland cement

NASA Astrophysics Data System (ADS)

Kurudirek, Murat; Türkmen, İbrahim; Özdemir, Yüksel

2009-09-01

Total mass attenuation coefficients, mean free paths (MFP), half-value (HVT) and tenth-value (TVT) thicknesses of Portland cement and three mixtures have been calculated in function of the energy from 1 keV to 100 GeV. Both in the low- and high-energy region there were significant variations in those parameters where photoelectric process and pair production partially dominates, respectively. In general, the attenuation parameters were found to vary with chemical composition, density of given material and photon energy.

Structure, bonding nature, and binding energy of alkanethiolate on As-rich GaAs (001) surface: a density functional theory study.

PubMed

Voznyy, Oleksandr; Dubowski, Jan J

2006-11-30

Chemisorption of alkanethiols on As-rich GaAs (001) surface under a low coverage condition was studied using first principles density functional calculations in a periodic supercell approach. The thiolate adsorption site, tilt angle and its direction are dictated by the high directionality of As dangling bond and sulfur 3p orbital participating in bonding and steric repulsion of the first three CH2 units from the surface. Small charge transfer between thiolate and surface, strong dependence of total energy on tilt angle, and a relatively short length of 2.28 A of the S-As bond indicate the highly covalent nature of the bonding. Calculated binding energy of 2.1 eV is consistent with the available experimental data.

Distribution functions of air-scattered gamma rays above isotropic plane sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael, J A; Lamonds, H A

1967-06-01

Using the moments method of Spencer and Fano and a reconstruction technique suggested by Berger, the authors have calculated energy and angular distribution functions for air-scattered gamma rays emitied from infinite-plane isotropic monoenergetic sources as iunctions of source energy, radiation incidence angle at the detector, and detector altitude. Incremental and total buildup factors have been calculated for both number and exposure. The results are presented in tabular form for a detector located at altitudes of 3, 50, 100, 200, 300, 400, 500, and 1000 feet above source planes of 15 discrete energies spanning the range of 0.1 to 3.0 MeV.more » Calculational techniques including results of sensitivity studies are discussed and plots of typical results are presented. (auth)« less

Development of the hard and soft constraints based optimisation model for unit sizing of the hybrid renewable energy system designed for microgrid applications

NASA Astrophysics Data System (ADS)

Sundaramoorthy, Kumaravel

2017-02-01

The hybrid energy systems (HESs) based electricity generation system has become a more attractive solution for rural electrification nowadays. Economically feasible and technically reliable HESs are solidly based on an optimisation stage. This article discusses about the optimal unit sizing model with the objective function to minimise the total cost of the HES. Three typical rural sites from southern part of India have been selected for the application of the developed optimisation methodology. Feasibility studies and sensitivity analysis on the optimal HES are discussed elaborately in this article. A comparison has been carried out with the Hybrid Optimization Model for Electric Renewable optimisation model for three sites. The optimal HES is found with less total net present rate and rate of energy compared with the existing method

Measurement of ν μ-induced charged-current neutral pion production cross sections on mineral oil at E vϵ0.5–2.0 GeV

DOE PAGES

Aguilar-Arevalo, A. A.; Anderson, C. E.; Bazarko, A. O.; ...

2011-03-23

Using a custom 3-Cerenkov ring fitter, we report cross sections for ν μ-induced charged-current single π⁰ production on mineral oil (CH₂) from a sample of 5810 candidate events with 57% signal purity over an energy range of 0.5–2.0 GeV. This includes measurements of the absolute total cross section as a function of neutrino energy, and flux-averaged differential cross sections measured in terms of Q², μ⁻ kinematics, and π⁰ kinematics. The sample yields a flux-averaged total cross section of (9.2±0.3 stat±1.5 syst)×10⁻³⁹ cm²/CH² at mean neutrino energy of 0.965 GeV.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahu, Sivabrata, E-mail: siva1987@iopb.res.in; Parashar, S. K. S., E-mail: sksparashar@yahoo.com; Rout, G. C., E-mail: gcr@iopb.res.in

We address here a tight-binding theoretical model calculation for AA-stacked bi-layer graphene taking into account of a biased potential between two layers to study the density of states and the band dispersion within the total Brillouin zone. We have calculated the electronic Green’s function for electron operator corresponding to A and B sub lattices by Zubarev’s Green’s function technique from which the electronic density of states and the electron band energy dispersion are calculated. The numerically computed density of states and band energy dispersions are investigated by tuning the biased potential to exhibit the band gap by varying the differentmore » physical parameters.« less

Exact relations for energy transfer in self-gravitating isothermal turbulence

NASA Astrophysics Data System (ADS)

Banerjee, Supratik; Kritsuk, Alexei G.

2017-11-01

Self-gravitating isothermal supersonic turbulence is analyzed in the asymptotic limit of large Reynolds numbers. Based on the inviscid invariance of total energy, an exact relation is derived for homogeneous (not necessarily isotropic) turbulence. A modified definition for the two-point energy correlation functions is used to comply with the requirement of detailed energy equipartition in the acoustic limit. In contrast to the previous relations (S. Galtier and S. Banerjee, Phys. Rev. Lett. 107, 134501 (2011), 10.1103/PhysRevLett.107.134501; S. Banerjee and S. Galtier, Phys. Rev. E 87, 013019 (2013), 10.1103/PhysRevE.87.013019), the current exact relation shows that the pressure dilatation terms play practically no role in the energy cascade. Both the flux and source terms are written in terms of two-point differences. Sources enter the relation in a form of mixed second-order structure functions. Unlike the kinetic and thermodynamic potential energies, the gravitational contribution is absent from the flux term. An estimate shows that, for the isotropic case, the correlation between density and gravitational acceleration may play an important role in modifying the energy transfer in self-gravitating turbulence. The exact relation is also written in an alternative form in terms of two-point correlation functions, which is then used to describe scale-by-scale energy budget in spectral space.

Derivation and application of the reciprocity relations for radiative transfer with internal illumination

NASA Technical Reports Server (NTRS)

Cogley, A. C.

1975-01-01

A Green's function formulation is used to derive basic reciprocity relations for planar radiative transfer in a general medium with internal illumination. Reciprocity (or functional symmetry) allows an explicit and generalized development of the equivalence between source and probability functions. Assuming similar symmetry in three-dimensional space, a general relationship is derived between planar-source intensity and point-source total directional energy. These quantities are expressed in terms of standard (universal) functions associated with the planar medium, while all results are derived from the differential equation of radiative transfer.

Design of exchange-correlation functionals through the correlation factor approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavlíková Přecechtělová, Jana, E-mail: j.precechtelova@gmail.com, E-mail: Matthias.Ernzerhof@UMontreal.ca; Institut für Chemie, Theoretische Chemie / Quantenchemie, Sekr. C7, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin; Bahmann, Hilke

The correlation factor model is developed in which the spherically averaged exchange-correlation hole of Kohn-Sham theory is factorized into an exchange hole model and a correlation factor. The exchange hole model reproduces the exact exchange energy per particle. The correlation factor is constructed in such a manner that the exchange-correlation energy correctly reduces to exact exchange in the high density and rapidly varying limits. Four different correlation factor models are presented which satisfy varying sets of physical constraints. Three models are free from empirical adjustments to experimental data, while one correlation factor model draws on one empirical parameter. The correlationmore » factor models are derived in detail and the resulting exchange-correlation holes are analyzed. Furthermore, the exchange-correlation energies obtained from the correlation factor models are employed to calculate total energies, atomization energies, and barrier heights. It is shown that accurate, non-empirical functionals can be constructed building on exact exchange. Avenues for further improvements are outlined as well.« less

Surface energy effect on nonlinear buckling and postbuckling behavior of functionally graded piezoelectric cylindrical nanoshells under lateral pressure

NASA Astrophysics Data System (ADS)

Fang, Xue-Qian; Zhu, Chang-Song; Liu, Jin-Xi; Zhao, Jing

2018-04-01

In this paper, the surface energy effect on the nonlinear buckling and postbuckling behavior of functionally graded piezoelectric (FGP) cylindrical nanoshells subjected to lateral pressure is studied based on the electro-elastic surface/interface theory together with von-Kármán-Donnell-type kinematics of nonlinearity. The total strain energy of the FGP nanoshell, including surface energy, is derived by considering the constitutive formulations of surface phase. The principle of minimum potential energy is utilized to establish the nonlinear governing differential equations, and the singular perturbation technique is employed to obtain the asymptotic solutions. Then, two sets of comparison are conducted to validate the present work, and some numerical examples are given to study the effects of surface parameters, power law index and aspect ratio on the buckling and postbuckling behavior of FGP nanoshells. The results show that the critical buckling load and postbuckling path of FGP nanoshell are significantly size-dependent.

First-principles study of MoS2 and MoSe2 nanoclusters in the framework of evolutionary algorithm and density functional theory

NASA Astrophysics Data System (ADS)

Hashemi, Zohreh; Rafiezadeh, Shohreh; Hafizi, Roohollah; Hashemifar, S. Javad; Akbarzadeh, Hadi

2018-04-01

Evolutionary algorithm is combined with full-potential ab initio calculations to investigate conformational space of (MoS2)n and (MoSe2)n (n = 1-10) nanoclusters and to identify the lowest energy structural isomers of these systems. It is argued that within both BLYP and PBE functionals, these nanoclusters favor sandwiched planar configurations, similar to their ideal planar sheets. The second order difference in total energy (Δ2 E) of the lowest energy isomers is computed to estimate the abundance of the clusters at different sizes and to determine the magic sizes of (MoS2)n and (MoSe2)n nanoclusters. In order to investigate the electronic properties of nanoclusters, their energy gap is calculated by several methods, including hybrid functionals (B3LYP and PBE0), GW approach, and Δ scf method. At the end, the vibrational modes of the lowest lying isomers are calculated by using the force constants method and the IR active modes of the systems are identified. The vibrational spectra are used to calculate the Helmholtz free energy of the systems and then to investigate abundance of the nanoclusters at finite temperatures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Vincent; Vogt, Ramona

Here, we explore polarized heavy quarkonium production using the color evaporation model at leading order. We present the polarized to total yield ratio as a function of center of mass energy and rapidity in p+p collisions. At energies far above the Q¯Q production threshold, we find charmonium and bottomonium production to be longitudinally polarized (J z = 0). The quarkonium states are also longitudinally polarized at central rapidity, becoming transversely polarized (J z = ±1) at the most forward rapidities.

Direct Electricity from Heat: A Solution to Assist Aircraft Power Demands

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2010-01-01

A thermionic device produces an electrical current with the application of a thermal gradient whereby the temperature at one electrode provides enough thermal energy to eject electrons. The system is totally predicated on the thermal gradient and the work function of the electrode collector relative to the emitter electrode. Combined with a standard thermoelectric device high efficiencies may result, capable of providing electrical energy from the waste heat of gas turbine engines.

An optimized full-configuration-interaction nuclear orbital approach to a ``hard-core'' interaction problem: Application to (3He)N-Cl2(B) clusters (N<=4)

NASA Astrophysics Data System (ADS)

de Lara-Castells, M. P.; Villarreal, P.; Delgado-Barrio, G.; Mitrushchenkov, A. O.

2009-11-01

An efficient full-configuration-interaction nuclear orbital treatment has been recently developed as a benchmark quantum-chemistry-like method to calculate ground and excited "solvent" energies and wave functions in small doped ΔEest clusters (N ≤4) [M. P. de Lara-Castells, G. Delgado-Barrio, P. Villarreal, and A. O. Mitrushchenkov, J. Chem. Phys. 125, 221101 (2006)]. Additional methodological and computational details of the implementation, which uses an iterative Jacobi-Davidson diagonalization algorithm to properly address the inherent "hard-core" He-He interaction problem, are described here. The convergence of total energies, average pair He-He interaction energies, and relevant one- and two-body properties upon increasing the angular part of the one-particle basis set (expanded in spherical harmonics) has been analyzed, considering Cl2 as the dopant and a semiempirical model (T-shaped) He-Cl2(B) potential. Converged results are used to analyze global energetic and structural aspects as well as the configuration makeup of the wave functions, associated with the ground and low-lying "solvent" excited states. Our study reveals that besides the fermionic nature of H3e atoms, key roles in determining total binding energies and wave-function structures are played by the strong repulsive core of the He-He potential as well as its very weak attractive region, the most stable arrangement somehow departing from the one of N He atoms equally spaced on equatorial "ring" around the dopant. The present results for N =4 fermions indicates the structural "pairing" of two H3e atoms at opposite sides on a broad "belt" around the dopant, executing a sort of asymmetric umbrella motion. This pairing is a compromise between maximizing the H3e-H3e and the He-dopant attractions, and suppressing at the same time the "hard-core" repulsion. Although the He-He attractive interaction is rather weak, its contribution to the total energy is found to scale as a power of three and it thus increasingly affects the pair density distributions as the cluster grows in size.

Double differential cross sections for proton induced electron emission from molecular analogues of DNA constituents for energies in the Bragg peak region

NASA Astrophysics Data System (ADS)

Rudek, Benedikt; Bennett, Daniel; Bug, Marion U.; Wang, Mingjie; Baek, Woon Yong; Buhr, Ticia; Hilgers, Gerhard; Champion, Christophe; Rabus, Hans

2016-09-01

For track structure simulations in the Bragg peak region, measured electron emission cross sections of DNA constituents are required as input for developing parameterized model functions representing the scattering probabilities. In the present work, double differential cross sections were measured for the electron emission from vapor-phase pyrimidine, tetrahydrofuran, and trimethyl phosphate that are structural analogues to the base, the sugar, and the phosphate residue of the DNA, respectively. The range of proton energies was from 75 keV to 135 keV, the angles ranged from 15° to 135°, and the electron energies were measured from 10 eV to 200 eV. Single differential and total electron emission cross sections are derived by integration over angle and electron energy and compared to the semi-empirical Hansen-Kocbach-Stolterfoht (HKS) model and a quantum mechanical calculation employing the first Born approximation with corrected boundary conditions (CB1). The CB1 provides the best prediction of double and single differential cross section, while total cross sections can be fitted with semi-empirical models. The cross sections of the three samples are proportional to their total number of valence electrons.

Simultaneous measurement of (n,{gamma}) and (n,fission) cross sections with the DANCE 4{pi} BaF2 array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.

2006-03-13

Neutron capture cross section measurements on many of the actinides are complicated by low-energy neutron-induced fission, which competes with neutron capture to varying degrees depending on the nuclide of interest. Measurements of neutron capture on 235U using the Detector for Advanced Neutron Capture Experiments (DANCE) have shown that we can partially resolve capture from fission events based on total photon calorimetry (i.e. total {gamma}-ray energy and {gamma}-ray multiplicity per event). The addition of a fission-tagging detector to the DANCE array will greatly improve our ability to separate these two competing processes so that improved neutron capture and (n,{gamma})/(n,fission) cross sectionmore » ratio measurements can be obtained. The addition of a fission-tagging detector to the DANCE array will also provide a means to study several important issues associated with neutron-induced fission, including (n,fission) cross sections as a function of incident neutron energy, and total energy and multiplicity of prompt fission photons. We have focused on two detector designs with complementary capabilities, a parallel-plate avalanche counter and an array of solar cells.« less

Threshold singularities in a Fermi gas with attractive potential in one dimension

DOE PAGES

Schlottmann, P.; Zvyagin, A. A.

2015-01-15

We consider the one-dimensional gas of fermions with spin S interacting via an attractive δ-function potential using the Bethe Ansatz solution. In zero magnetic field the atoms form bound states of N=2S + 1 fermions, i.e. generalized Cooper states with each atom having a different spin component. For low energy excitations the system is a Luttinger liquid and is properly described by a conformal field theory with conformal charge c=1. The linear dispersion of a Luttinger liquid is asymptotically exact in the low-energy limit where the band curvature terms in the dispersion are irrelevant. For higher energy excitations, however, themore » spectral function displays deviations in the neighborhood of the single-particle (hole) energy, which can be described by an effective X-ray edge type model. Using the Bethe Ansatz solution we obtain expressions for the critical exponents for the single-particle (hole) Green’s function. This model can be relevant in the context of ultracold atoms with effective total spin S confined to an elongated optical trap.« less

Development of a Multicenter Density Functional Tight Binding Model for Plutonium Surface Hydriding.

PubMed

Goldman, Nir; Aradi, Bálint; Lindsey, Rebecca K; Fried, Laurence E

2018-05-08

We detail the creation of a multicenter density functional tight binding (DFTB) model for hydrogen on δ-plutonium, using a framework of new Slater-Koster interaction parameters and a repulsive energy based on the Chebyshev Interaction Model for Efficient Simulation (ChIMES), where two- and three-center atomic interactions are represented by linear combinations of Chebyshev polynomials. We find that our DFTB/ChIMES model yields a total electron density of states for bulk δ-Pu that compares well to that from Density Functional Theory, as well as to a grid of energy calculations representing approximate H 2 dissociation paths on the δ-Pu (100) surface. We then perform molecular dynamics simulations and minimum energy pathway calculations to determine the energetics of surface dissociation and subsurface diffusion on the (100) and (111) surfaces. Our approach allows for the efficient creation of multicenter repulsive energies with a relatively small investment in initial DFT calculations. Our efforts are particularly pertinent to studies that rely on quantum calculations for interpretation and validation, such as experimental determination of chemical reactivity both on surfaces and in condensed phases.

Enhanced laser-energy coupling to dense plasmas driven by recirculating electron currents

NASA Astrophysics Data System (ADS)

Gray, R. J.; Wilson, R.; King, M.; Williamson, S. D. R.; Dance, R. J.; Armstrong, C.; Brabetz, C.; Wagner, F.; Zielbauer, B.; Bagnoud, V.; Neely, D.; McKenna, P.

2018-03-01

The absorption of laser energy and dynamics of energetic electrons in dense plasma is fundamental to a range of intense laser-driven particle and radiation generation mechanisms. We measure the total reflected and scattered laser energy as a function of intensity, distinguishing between the influence of pulse energy and focal spot size on total energy absorption, in the interaction with thin foils. We confirm a previously published scaling of absorption with intensity by variation of laser pulse energy, but find a slower scaling when changing the focal spot size. 2D particle-in-cell simulations show that the measured differences arise due to energetic electrons recirculating within the target and undergoing multiple interactions with the laser pulse, which enhances absorption in the case of large focal spots. This effect is also shown to be dependent on the laser pulse duration, the target thickness and the electron beam divergence. The parameter space over which this absorption enhancement occurs is explored via an analytical model. The results impact our understanding of the fundamental physics of laser energy absorption in solids and thus the development of particle and radiation sources driven by intense laser–solid interactions.

Novel Role of Superfluidity in Low-Energy Nuclear Reactions.

PubMed

Magierski, Piotr; Sekizawa, Kazuyuki; Wlazłowski, Gabriel

2017-07-28

We demonstrate, within symmetry unrestricted time-dependent density functional theory, the existence of new effects in low-energy nuclear reactions which originate from superfluidity. The dynamics of the pairing field induces solitonic excitations in the colliding nuclear systems, leading to qualitative changes in the reaction dynamics. The solitonic excitation prevents collective energy dissipation and effectively suppresses the fusion cross section. We demonstrate how the variations of the total kinetic energy of the fragments can be traced back to the energy stored in the superfluid junction of colliding nuclei. Both contact time and scattering angle in noncentral collisions are significantly affected. The modification of the fusion cross section and possibilities for its experimental detection are discussed.

The spin-partitioned total position-spread tensor: An application to Heisenberg spin chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fertitta, Edoardo; Paulus, Beate; El Khatib, Muammar

2015-12-28

The spin partition of the Total Position-Spread (TPS) tensor has been performed for one-dimensional Heisenberg chains with open boundary conditions. Both the cases of a ferromagnetic (high-spin) and an anti-ferromagnetic (low-spin) ground-state have been considered. In the case of a low-spin ground-state, the use of alternating magnetic couplings allowed to investigate the effect of spin-pairing. The behavior of the spin-partitioned TPS (SP-TPS) tensor as a function of the number of sites turned to be closely related to the presence of an energy gap between the ground-state and the first excited-state at the thermodynamic limit. Indeed, a gapped energy spectrum ismore » associated to a linear growth of the SP-TPS tensor with the number of sites. On the other hand, in gapless situations, the spread presents a faster-than-linear growth, resulting in the divergence of its per-site value. Finally, for the case of a high-spin wave function, an analytical expression of the dependence of the SP-TPS on the number of sites n and the total spin-projection S{sub z} has been derived.« less

Energy in elastic fiber embedded in elastic matrix containing incident SH wave

NASA Technical Reports Server (NTRS)

Williams, James H., Jr.; Nagem, Raymond J.

1989-01-01

A single elastic fiber embedded in an infinite elastic matrix is considered. An incident plane SH wave is assumed in the infinite matrix, and an expression is derived for the total energy in the fiber due to the incident SH wave. A nondimensional form of the fiber energy is plotted as a function of the nondimensional wavenumber of the SH wave. It is shown that the fiber energy attains maximum values at specific values of the wavenumber of the incident wave. The results obtained here are interpreted in the context of phenomena observed in acousto-ultrasonic experiments on fiber reinforced composite materials.

Response functions for computing absorbed dose to skeletal tissues from photon irradiation—an update

NASA Astrophysics Data System (ADS)

Johnson, Perry B.; Bahadori, Amir A.; Eckerman, Keith F.; Lee, Choonsik; Bolch, Wesley E.

2011-04-01

A comprehensive set of photon fluence-to-dose response functions (DRFs) is presented for two radiosensitive skeletal tissues—active and total shallow marrow—within 15 and 32 bone sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron-absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon micro-CT images of trabecular spongiosa taken from a 40 year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, and a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In this study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma coefficients for active marrow, inactive marrow, trabecular bone and spongiosa at higher energies are calculated using the DRF algorithm setting the electron-absorbed fraction for self-irradiation to unity. By comparing kerma coefficients and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985 Br. J. Radiol. 58 345-56) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R2 = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites representing the first such derivation for this target tissue.

Response functions for computing absorbed dose to skeletal tissues from photon irradiation--an update.

PubMed

Johnson, Perry B; Bahadori, Amir A; Eckerman, Keith F; Lee, Choonsik; Bolch, Wesley E

2011-04-21

A comprehensive set of photon fluence-to-dose response functions (DRFs) is presented for two radiosensitive skeletal tissues-active and total shallow marrow-within 15 and 32 bone sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron-absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon micro-CT images of trabecular spongiosa taken from a 40 year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, and a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In this study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma coefficients for active marrow, inactive marrow, trabecular bone and spongiosa at higher energies are calculated using the DRF algorithm setting the electron-absorbed fraction for self-irradiation to unity. By comparing kerma coefficients and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985 Br. J. Radiol. 58 345-56) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R(2) = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites representing the first such derivation for this target tissue.

RESPONSE FUNCTIONS FOR COMPUTING ABSORBED DOSE TO SKELETAL TISSUES FROM PHOTON IRRADIATION – AN UPDATE

PubMed Central

Johnson, Perry; Bahadori, Amir; Eckerman, Keith; Lee, Choonsik; Bolch, Wesley E.

2014-01-01

A comprehensive set of photon fluence-to-dose response functions (DRFs) are presented for two radiosensitive skeletal tissues – active and total shallow marrow – within 15 and 32 bones sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon microCT images of trabecular spongiosa taken from a 40-year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, as well as a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In the present study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma factors for active marrow, inactive marrow, trabecular bone, and spongiosa at higher energies are calculated using the DRF algorithm setting the electron absorbed fraction for self-irradiation to unity. By comparing kerma factors and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R2 = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites PMID:21427484

The Effect of Post-Burst Energy on Exploding Bridgewire Output

NASA Astrophysics Data System (ADS)

Lee, Elizabeth; Bowden, Mike

2015-06-01

For an EBW detonator, as the fireset energy is increased from threshold to all-fire level the post-burst energy delivered to the detonator increases, and the function times decrease. To gain an understanding of the processes through which the post-burst electrical energy influences the function times the effect of the post-burst energy on the explosion of bridgewires was studied. A fireset was developed which enabled the post-burst energy to be varied independent of the burst energy by terminating the current flow at pre-selected times. The effect of this on the bridgewires was characterised at a range of firing voltages and a range of termination times. The response of the bridgewire was characterised using Photonic Doppler Velocimetry. The velocimetry trace detected two families of velocities. The first family had initial velocities in the range 1-2 km.s-1 and the second family had velocities in the range 0-0.5 km.s-1. The relative position of the two families depended on the post burst energy. The results show that a reduction in the post-burst energy and therefore the total delivered energy, but for a constant energy delivered to burst, corresponds to a decrease in the acceleration and peak velocity of the bridgewire / plasma at burst.

Extension of the self-consistent-charge density-functional tight-binding method: third-order expansion of the density functional theory total energy and introduction of a modified effective coulomb interaction.

PubMed

Yang, Yang; Yu, Haibo; York, Darrin; Cui, Qiang; Elstner, Marcus

2007-10-25

The standard self-consistent-charge density-functional-tight-binding (SCC-DFTB) method (Phys. Rev. B 1998, 58, 7260) is derived by a second-order expansion of the density functional theory total energy expression, followed by an approximation of the charge density fluctuations by charge monopoles and an effective damped Coulomb interaction between the atomic net charges. The central assumptions behind this effective charge-charge interaction are the inverse relation of atomic size and chemical hardness and the use of a fixed chemical hardness parameter independent of the atomic charge state. While these approximations seem to be unproblematic for many covalently bound systems, they are quantitatively insufficient for hydrogen-bonding interactions and (anionic) molecules with localized net charges. Here, we present an extension of the SCC-DFTB method to incorporate third-order terms in the charge density fluctuations, leading to chemical hardness parameters that are dependent on the atomic charge state and a modification of the Coulomb scaling to improve the electrostatic treatment within the second-order terms. These modifications lead to a significant improvement in the description of hydrogen-bonding interactions and proton affinities of biologically relevant molecules.

Calculations with the quasirelativistic local-spin-density-functional theory for high-Z atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Y.; Whitehead, M.A.

1988-10-01

The generalized-exchange local-spin-density-functional theory (LSD-GX) with relativistic corrections of the mass velocity and Darwin terms has been used to calculate statistical total energies for the neutral atoms, the positive ions, and the negative ions for high-Z elements. The effect of the correlation and relaxation correction on the statistical total energy is discussed. Comparing the calculated results for the ionization potentials and electron affinities for the atoms (atomic number Z from 37 to 56 and 72 to 80) with experiment, shows that for the atoms rubidium to barium both the LSD-GX and the quasirelativistic LSD-GX, with self-interaction correction, Gopinathan, Whitehead, andmore » Bogdanovic's Fermi-hole parameters (Phys. Rev. A 14, 1 (1976)), and Vosko, Wilk, and Nusair's correlation correction (Can. J. Phys. 58, 1200 (1980)), are very good methods for calculating ionization potentials and electron affinities. For the atoms hafnium to mercury the relativistic effect has to be considered.« less

Suppressing the image smear of the vibration modulation transfer function for remote-sensing optical cameras.

PubMed

Li, Jin; Liu, Zilong; Liu, Si

2017-02-20

In on-board photographing processes of satellite cameras, the platform vibration can generate image motion, distortion, and smear, which seriously affect the image quality and image positioning. In this paper, we create a mathematical model of a vibrating modulate transfer function (VMTF) for a remote-sensing camera. The total MTF of a camera is reduced by the VMTF, which means the image quality is degraded. In order to avoid the degeneration of the total MTF caused by vibrations, we use an Mn-20Cu-5Ni-2Fe (M2052) manganese copper alloy material to fabricate a vibration-isolation mechanism (VIM). The VIM can transform platform vibration energy into irreversible thermal energy with its internal twin crystals structure. Our experiment shows the M2052 manganese copper alloy material is good enough to suppress image motion below 125 Hz, which is the vibration frequency of satellite platforms. The camera optical system has a higher MTF after suppressing the vibration of the M2052 material than before.

The Human Genome Initiative of the Department of Energy

DOE R&D Accomplishments Database

1988-01-01

The structural characterization of genes and elucidation of their encoded functions have become a cornerstone of modern health research, biology and biotechnology. A genome program is an organized effort to locate and identify the functions of all the genes of an organism. Beginning with the DOE-sponsored, 1986 human genome workshop at Santa Fe, the value of broadly organized efforts supporting total genome characterization became a subject of intensive study. There is now national recognition that benefits will rapidly accrue from an effective scientific infrastructure for total genome research. In the US genome research is now receiving dedicated funds. Several other nations are implementing genome programs. Supportive infrastructure is being improved through both national and international cooperation. The Human Genome Initiative of the Department of Energy (DOE) is a focused program of Resource and Technology Development, with objectives of speeding and bringing economies to the national human genome effort. This report relates the origins and progress of the Initiative.

The local phase transitions of the solvent in the neighborhood of a solvophobic polymer at high pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Budkov, Yu. A., E-mail: urabudkov@rambler.ru; National Research University Higher School of Economics, Moscow; Department of Chemistry, Lomonosov Moscow State University, Moscow

2014-11-28

We investigate local phase transitions of the solvent in the neighborhood of a solvophobic polymer chain which is induced by a change of the polymer-solvent repulsion and the solvent pressure in the bulk solution. We describe the polymer in solution by the Edwards model, where the conditional partition function of the polymer chain at a fixed radius of gyration is described by a mean-field theory. The contributions of the polymer-solvent and the solvent-solvent interactions to the total free energy are described within the mean-field approximation. We obtain the total free energy of the solution as a function of the radiusmore » of gyration and the average solvent number density within the gyration volume. The resulting system of coupled equations is solved varying the polymer-solvent repulsion strength at high solvent pressure in the bulk. We show that the coil-globule (globule-coil) transition occurs accompanied by a local solvent evaporation (condensation) within the gyration volume.« less

Pioneer Venus Orbiter planar retarding potential analyzer plasma experiment

NASA Technical Reports Server (NTRS)

Knudsen, W. C.; Bakke, J.; Spenner, K.; Novak, V.

1980-01-01

The retarding potential analyzer (RPA) on the Pioneer Venus Orbiter Mission measures most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. Several functions not previously used in RPA's were developed and incorporated into this instrument to accomplish these measurements on a spinning spacecraft with a small bit rate. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection.

Species richness and biomass explain spatial turnover in ecosystem functioning across tropical and temperate ecosystems.

PubMed

Barnes, Andrew D; Weigelt, Patrick; Jochum, Malte; Ott, David; Hodapp, Dorothee; Haneda, Noor Farikhah; Brose, Ulrich

2016-05-19

Predicting ecosystem functioning at large spatial scales rests on our ability to scale up from local plots to landscapes, but this is highly contingent on our understanding of how functioning varies through space. Such an understanding has been hampered by a strong experimental focus of biodiversity-ecosystem functioning research restricted to small spatial scales. To address this limitation, we investigate the drivers of spatial variation in multitrophic energy flux-a measure of ecosystem functioning in complex communities-at the landscape scale. We use a structural equation modelling framework based on distance matrices to test how spatial and environmental distances drive variation in community energy flux via four mechanisms: species composition, species richness, niche complementarity and biomass. We found that in both a tropical and a temperate study region, geographical and environmental distance indirectly influence species richness and biomass, with clear evidence that these are the dominant mechanisms explaining variability in community energy flux over spatial and environmental gradients. Our results reveal that species composition and trait variability may become redundant in predicting ecosystem functioning at the landscape scale. Instead, we demonstrate that species richness and total biomass may best predict rates of ecosystem functioning at larger spatial scales. © 2016 The Author(s).

A variation-perturbation method for atomic and molecular interactions. I - Theory. II - The interaction potential and van der Waals molecule for Ne-HF

NASA Astrophysics Data System (ADS)

Gallup, G. A.; Gerratt, J.

1985-09-01

The van der Waals energy between the two parts of a system is a very small fraction of the total electronic energy. In such cases, calculations have been based on perturbation theory. However, such an approach involves certain difficulties. For this reason, van der Waals energies have also been directly calculated from total energies. But such a method has definite limitations as to the size of systems which can be treated, and recently ab initio calculations have been combined with damped semiempirical long-range dispersion potentials to treat larger systems. In this procedure, large basis set superposition errors occur, which must be removed by the counterpoise method. The present investigation is concerned with an approach which is intermediate between the previously considered procedures. The first step in the new approach involves a variational calculation based upon valence bond functions. The procedure includes also the optimization of excited orbitals, and an approximation of atomic integrals and Hamiltonian matrix elements.

First-Principles Prediction of Densities of Amorphous Materials: The Case of Amorphous Silicon

NASA Astrophysics Data System (ADS)

Furukawa, Yoritaka; Matsushita, Yu-ichiro

2018-02-01

A novel approach to predict the atomic densities of amorphous materials is explored on the basis of Car-Parrinello molecular dynamics (CPMD) in density functional theory. Despite the determination of the atomic density of matter being crucial in understanding its physical properties, no first-principles method has ever been proposed for amorphous materials until now. We have extended the conventional method for crystalline materials in a natural manner and pointed out the importance of the canonical ensemble of the total energy in the determination of the atomic densities of amorphous materials. To take into account the canonical distribution of the total energy, we generate multiple amorphous structures with several different volumes by CPMD simulations and average the total energies at each volume. The density is then determined as the one that minimizes the averaged total energy. In this study, this approach is implemented for amorphous silicon (a-Si) to demonstrate its validity, and we have determined the density of a-Si to be 4.1% lower and its bulk modulus to be 28 GPa smaller than those of the crystal, which are in good agreement with experiments. We have also confirmed that generating samples through classical molecular dynamics simulations produces a comparable result. The findings suggest that the presented method is applicable to other amorphous systems, including those for which experimental knowledge is lacking.

Life cycle energy use, costs, and greenhouse gas emission of broiler farms in different production systems in Iran-a case study of Alborz province.

PubMed

Pishgar-Komleh, Seyyed Hassan; Akram, Asadollah; Keyhani, Alireza; van Zelm, Rosalie

2017-07-01

In order to achieve sustainable development in agriculture, it is necessary to quantify and compare the energy, economic, and environmental aspects of products. This paper studied the energy, economic, and greenhouse gas (GHG) emission patterns in broiler chicken farms in the Alborz province of Iran. We studied the effect of the broiler farm size as different production systems on the energy, economic, and environmental indices. Energy use efficiency (EUE) and benefit-cost ratio (BCR) were 0.16 and 1.11, respectively. Diesel fuel and feed contributed the most in total energy inputs, while feed and chicks were the most important inputs in economic analysis. GHG emission calculations showed that production of 1000 birds produces 19.13 t CO 2-eq and feed had the highest share in total GHG emission. Total GHG emissions based on different functional units were 8.5 t CO 2-eq per t of carcass and 6.83 kg CO 2-eq per kg live weight. Results of farm size effect on EUE revealed that large farms had better energy management. For BCR, there was no significant difference between farms. Lower total GHG emissions were reported for large farms, caused by better management of inputs and fewer bird losses. Large farms with more investment had more efficient equipment, resulting in a decrease of the input consumption. In view of our study, it is recommended to support the small-scale broiler industry by providing subsidies to promote the use of high-efficiency equipment. To decrease the amount of energy usage and GHG emissions, replacing heaters (which use diesel fuel) with natural gas heaters can be considered. In addition to the above recommendations, the use of energy saving light bulbs may reduce broiler farm electricity consumption.

High precision measurements on fission-fragment de-excitation

NASA Astrophysics Data System (ADS)

Oberstedt, Stephan; Gatera, Angélique; Geerts, Wouter; Göök, Alf; Hambsch, Franz-Josef; Vidali, Marzio; Oberstedt, Andreas

2017-11-01

In recent years nuclear fission has gained renewed interest both from the nuclear energy community and in basic science. The first, represented by the OECD Nuclear Energy Agency, expressed the need for more accurate fission cross-section and fragment yield data for safety assessments of Generation IV reactor systems. In basic science modelling made much progress in describing the de-excitation mechanism of neutron-rich isotopes, e.g. produced in nuclear fission. Benchmarking the different models require a precise experimental data on prompt fission neutron and γ-ray emission, e.g. multiplicity, average energy per particle and total dissipated energy per fission, preferably as function of fission-fragment mass and total kinetic energy. A collaboration of scientists from JRC Geel (formerly known as JRC IRMM) and other institutes took the lead in establishing a dedicated measurement programme on prompt fission neutron and γ-ray characteristics, which has triggered even more measurement activities around the world. This contribution presents new advanced instrumentation and methodology we use to generate high-precision spectral data and will give a flavour of future data needs and opportunities.

States of direct and indirect excitons in strained zinc-blende GaN/InGaN asymmetric quantum wells

NASA Astrophysics Data System (ADS)

Rojas-Briseño, J. G.; Martínez-Orozco, J. C.; Mora-Ramos, M. E.

2017-12-01

The total and binding energies of excitons in step-like asymmetric quantum wells made of zincblende GaN/InxlGa(1-xl)N/InxrGa(1-xr)N/GaN are theoretically reported. It is discussed how the asymmetry in the carrier confinement leads to singular behaviors in the exciton binding energy, allowing to observe both direct and indirect exciton states in the heterostructure. The study is carried out with the use of the effective mass approximation. The effects of strain are taken into account and a comparison of the results obtained for both strained and unstrained situations is presented. Exciton energy shows a decreasing behavior when the size of the effective confinement region is augmented. The total exciton energy as well as the binding energy are reported as functions of the indium concentration and quantum well width. In addition, the results of the calculation of the photoluminescence peak are presented. For this latter quantity, our results for the limiting case of a single zinc-blende GaN/InGaN quantum well show very good agreement with published experimental ones.

Thermoluminescent dosimetry in electron beams: energy dependence.

PubMed

Robar, V; Zankowski, C; Olivares Pla, M; Podgorsak, E B

1996-05-01

The response of thermoluminescent dosimeters to electron irradiations depends on the radiation dose, mean electron energy at the position of the dosimeter in phantom, and the size of the dosimeter. In this paper the semi-empirical expression proposed by Holt et al. [Phys. Med. Biol. 20, 559-570 (1975)] is combined with the calculated electron dose fraction to determine the thermoluminescent dosimetry (TLD) response as a function of the mean electron energy and the dosimeter size. The electron and photon dose fractions, defined as the relative contributions of electrons and bremsstrahlung photons to the total dose for a clinical electron beam, are calculated with Monte Carlo techniques using EGS4. Agreement between the calculated and measured TLD response is very good. We show that the considerable reduction in TLD response per unit dose at low electron energies, i.e., at large depths in phantom, is offset by an ever-increasing relative contribution of bremsstrahlung photons to the total dose of clinical electron beams. This renders the TLD sufficiently reliable for dose measurements over the entire electron depth dose distribution despite the dependence of the TLD response on electron beam energy.

Generic expansion of the Jastrow correlation factor in polynomials satisfying symmetry and cusp conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lüchow, Arne, E-mail: luechow@rwth-aachen.de; Jülich Aachen Research Alliance; Sturm, Alexander

2015-02-28

Jastrow correlation factors play an important role in quantum Monte Carlo calculations. Together with an orbital based antisymmetric function, they allow the construction of highly accurate correlation wave functions. In this paper, a generic expansion of the Jastrow correlation function in terms of polynomials that satisfy both the electron exchange symmetry constraint and the cusp conditions is presented. In particular, an expansion of the three-body electron-electron-nucleus contribution in terms of cuspless homogeneous symmetric polynomials is proposed. The polynomials can be expressed in fairly arbitrary scaling function allowing a generic implementation of the Jastrow factor. It is demonstrated with a fewmore » examples that the new Jastrow factor achieves 85%–90% of the total correlation energy in a variational quantum Monte Carlo calculation and more than 90% of the diffusion Monte Carlo correlation energy.« less

Retarding potential analyzer for the Pioneer-Venus Orbiter Mission

NASA Technical Reports Server (NTRS)

Knudsen, W. C.; Bakke, J.; Spenner, K.; Novak, V.

1979-01-01

The retarding potential analyzer on the Pioneer-Venus Orbiter Mission has been designed to measure most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. To accomplish these measurements on a spinning vehicle with a small telemetry bit rate, several functions, including decision functions not previously used in RPA's, have been developed and incorporated into this instrument. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection. Extensive numerical simulation and plasma chamber tests have been conducted to verify adequacy of the design for the Pioneer Mission.

Invariant-mass and fractional-energy dependence of inclusive production of dihadrons in e + e - annihilation at s = 10.58 GeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidl, R.; Adachi, I.; Aihara, H.

The inclusive cross sections for dihadrons of charged pions and kaons (e +e - → hhX) in electronpositron annihilation are reported. They are obtained as a function of the total fractional energy and invariant mass for any di-hadron combination in the same hemisphere as defined by the thrust event-shape variable and its axis. Since same-hemisphere dihadrons can be assumed to originate predominantly from the same initial parton, di-hadron fragmentation functions are probed. These di-hadron fragmentationfunctions are needed as an unpolarized baseline in order to quantitatively understand related spindependent measurements in other processes and to apply them to the extraction ofmore » quark transversity distribution functions in the nucleon. The di-hadron cross sections are obtained from a 655 fb -1 data sample collected at or near the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e +e - collider.« less

Electromagnetic δ -function sphere

NASA Astrophysics Data System (ADS)

Parashar, Prachi; Milton, Kimball A.; Shajesh, K. V.; Brevik, Iver

2017-10-01

We develop a formalism to extend our previous work on the electromagnetic δ -function plates to a spherical surface. The electric (λe) and magnetic (λg) couplings to the surface are through δ -function potentials defining the dielectric permittivity and the diamagnetic permeability, with two anisotropic coupling tensors. The formalism incorporates dispersion. The electromagnetic Green's dyadic breaks up into transverse electric and transverse magnetic parts. We derive the Casimir interaction energy between two concentric δ -function spheres in this formalism and show that it has the correct asymptotic flat-plate limit. We systematically derive expressions for the Casimir self-energy and the total stress on a spherical shell using a δ -function potential, properly regulated by temporal and spatial point splitting, which are different from the conventional temporal point splitting. In the strong-coupling limit, we recover the usual result for the perfectly conducting spherical shell but in addition there is an integrated curvature-squared divergent contribution. For finite coupling, there are additional divergent contributions; in particular, there is a familiar logarithmic divergence occurring in the third order of the uniform asymptotic expansion that renders it impossible to extract a unique finite energy except in the case of an isorefractive sphere, which translates into λg=-λe.

Molecular wave function and effective adiabatic potentials calculated by extended multi-configuration time-dependent Hartree-Fock method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Tsuyoshi; Ide, Yoshihiro; Yamanouchi, Kaoru

We first calculate the ground-state molecular wave function of 1D model H{sub 2} molecule by solving the coupled equations of motion formulated in the extended multi-configuration time-dependent Hartree-Fock (MCTDHF) method by the imaginary time propagation. From the comparisons with the results obtained by the Born-Huang (BH) expansion method as well as with the exact wave function, we observe that the memory size required in the extended MCTDHF method is about two orders of magnitude smaller than in the BH expansion method to achieve the same accuracy for the total energy. Second, in order to provide a theoretical means to understandmore » dynamical behavior of the wave function, we propose to define effective adiabatic potential functions and compare them with the conventional adiabatic electronic potentials, although the notion of the adiabatic potentials is not used in the extended MCTDHF approach. From the comparison, we conclude that by calculating the effective potentials we may be able to predict the energy differences among electronic states even for a time-dependent system, e.g., time-dependent excitation energies, which would be difficult to be estimated within the BH expansion approach.« less

Curvature and frontier orbital energies in density functional theory

NASA Astrophysics Data System (ADS)

Kronik, Leeor; Stein, Tamar; Autschbach, Jochen; Govind, Niranjan; Baer, Roi

2013-03-01

Perdew et al. [Phys. Rev. Lett 49, 1691 (1982)] discovered and proved two different properties of exact Kohn-Sham density functional theory (DFT): (i) The exact total energy versus particle number is a series of linear segments between integer electron points; (ii) Across an integer number of electrons, the exchange-correlation potential may ``jump'' by a constant, known as the derivative discontinuity (DD). Here, we show analytically that in both the original and the generalized Kohn-Sham formulation of DFT, the two are in fact two sides of the same coin. Absence of a derivative discontinuity necessitates deviation from piecewise linearity, and the latter can be used to correct for the former, thereby restoring the physical meaning of the orbital energies. Using selected small molecules, we show that this results in a simple correction scheme for any underlying functional, including semi-local and hybrid functionals as well as Hartree-Fock theory, suggesting a practical correction for the infamous gap problem of DFT. Moreover, we show that optimally-tuned range-separated hybrid functionals can inherently minimize both DD and curvature, thus requiring no correction, and show that this can be used as a sound theoretical basis for novel tuning strategies.

A new response matrix for a 6LiI scintillator BSS system

NASA Astrophysics Data System (ADS)

Lacerda, M. A. S.; Méndez-Villafañe, R.; Lorente, A.; Ibañez, S.; Gallego, E.; Vega-Carrillo, H. R.

2017-10-01

A new response matrix was calculated for a Bonner Sphere Spectrometer (BSS) with a 6 LiI(Eu) scintillator, using the Monte Carlo N-Particle radiation transport code MCNPX. Responses were calculated for 6 spheres and the bare detector, for energies varying from 1.059E(-9) MeV to 105.9 MeV, with 20 equal-log(E)-width bins per energy decade, totalizing 221 energy groups. A comparison was done among the responses obtained in this work and other published elsewhere, for the same detector model. The calculated response functions were inserted in the response input file of the MAXED code and used to unfold the total and direct neutron spectra generated by the 241Am-Be source of the Universidad Politécnica de Madrid (UPM). These spectra were compared with those obtained using the same unfolding code with the Mares and Schraube matrix response.

Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolff, Wania, E-mail: wania@if.ufrj.br; Luna, Hugo; Sigaud, Lucas

Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful toolmore » to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.« less

Silicon Nanowire/Polymer Hybrid Solar Cell-Supercapacitor: A Self-Charging Power Unit with a Total Efficiency of 10.5.

PubMed

Liu, Ruiyuan; Wang, Jie; Sun, Teng; Wang, Mingjun; Wu, Changsheng; Zou, Haiyang; Song, Tao; Zhang, Xiaohong; Lee, Shuit-Tong; Wang, Zhong Lin; Sun, Baoquan

2017-07-12

An integrated self-charging power unit, combining a hybrid silicon nanowire/polymer heterojunction solar cell with a polypyrrole-based supercapacitor, has been demonstrated to simultaneously harvest solar energy and store it. By efficiency enhancement of the hybrid nanowire solar cells and a dual-functional titanium film serving as conjunct electrode of the solar cell and supercapacitor, the integrated system is able to yield a total photoelectric conversion to storage efficiency of 10.5%, which is the record value in all the integrated solar energy conversion and storage system. This system may not only serve as a buffer that diminishes the solar power fluctuations from light intensity, but also pave its way toward cost-effective high efficiency self-charging power unit. Finally, an integrated device based on ultrathin Si substrate is demonstrated to expand its feasibility and potential application in flexible energy conversion and storage devices.

Low- ν Flux and Total Charged-current Cross Sections in MINERvA

NASA Astrophysics Data System (ADS)

Ren, Lu

2014-03-01

The MINER νA experiment measures neutrino and antineutrino interaction cross sections on carbon and other nuclei. Cross section measurements require accurate knowledge of the incident neutrino flux. The ``low- ν'' flux technique uses a standard-candle cross section for events with low energy transfer to to the hadronic system to determine the incident flux. MINER νA will use low- ν fluxes for neutrinos and antineutrinos to tune production models used in beam simulations and to extract total cross sections as a function of energy. We present the low- ν flux technique adapted for the MINER νA data samples and preliminary results for the extracted low- ν fluxes in MINER νA. MINER νA will extend the range of antineutino charged-current cross section measurements to lower energies which are of interest to future accelerator oscillation experiments.

Microscopic Phase-Space Exploration Modeling of ^{258}Fm Spontaneous Fission.

PubMed

Tanimura, Yusuke; Lacroix, Denis; Ayik, Sakir

2017-04-14

We show that the total kinetic energy (TKE) of nuclei after the spontaneous fission of ^{258}Fm can be well reproduced using simple assumptions on the quantum collective phase space explored by the nucleus after passing the fission barrier. Assuming energy conservation and phase-space exploration according to the stochastic mean-field approach, a set of initial densities is generated. Each density is then evolved in time using the nuclear time-dependent density-functional theory with pairing. This approach goes beyond the mean-field theory by allowing spontaneous symmetry breaking as well as a wider dynamical phase-space exploration leading to larger fluctuations in collective space. The total kinetic energy and mass distributions are calculated. New information on the fission process: fluctuations in scission time, strong correlation between TKE and collective deformation, as well as prescission particle emission, are obtained. We conclude that fluctuations of the TKE and mass are triggered by quantum fluctuations.

[Increase of physical activity by improvement of the nutritional status].

PubMed

Torún, B

1989-09-01

Physical activity is affected by nutritional modifications and, in turn, influences growth, cognition, social behavior, work performance and other functions. Studies in preschool children showed that: 1. A decrease in energy intake during four to seven days reduced the time allocated to energy-demanding activities and increased sedentary activities. 2. Children with mild weight deficit were more sedentary than well-nourished counterparts. 3. Children became more active when nutritional status improved. 4. A 10% reduction in energy intake reduced total energy expenditure by 15% without affecting weight gain nor basal metabolism. Studies of men working in non-mechanized agriculture showed that: 1. Dietary improvements led to faster salaried work, reduction of napping time and greater physical activity after work. 2. An increase in energy intake increased total daily energy expenditure, tending to maintain energy balance and relatively stable body weight within the cyclic variations of the agricultural year. 3. Food supplementation did not necessarily improve productivity. Other labor incentives without dietary improvements increased energy expenditure during working hours, which resulted in weight loss. In conclusion, good health and nutrition provide the biological basis for adequate physical activity that may improve cognitive development, social interactions, economic productivity and the quality of life of an individual or a population, but other incentives are required for the optimal expression of that biologic potential.

Warm Body Temperature Facilitates Energy Efficient Cortical Action Potentials

PubMed Central

Yu, Yuguo; Hill, Adam P.; McCormick, David A.

2012-01-01

The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na+ channel inactivation, resulting in a marked reduction in overlap of the inward Na+, and outward K+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37–42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code. PMID:22511855

Thermal radiative and thermodynamic properties of solid and liquid uranium and plutonium carbides in the visible-near-infrared range

NASA Astrophysics Data System (ADS)

Fisenko, Anatoliy I.; Lemberg, Vladimir F.

2016-09-01

The knowledge of thermal radiative and thermodynamic properties of uranium and plutonium carbides under extreme conditions is essential for designing a new metallic fuel materials for next generation of a nuclear reactor. The present work is devoted to the study of the thermal radiative and thermodynamic properties of liquid and solid uranium and plutonium carbides at their melting/freezing temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and normal total emissivity are calculated using experimental data for the frequency dependence of the normal spectral emissivity of liquid and solid uranium and plutonium carbides in the visible-near infrared range. It is shown that the thermal radiative and thermodynamic functions of uranium carbide have a slight difference during liquid-to-solid transition. Unlike UC, such a difference between these functions have not been established for plutonium carbide. The calculated values for the normal total emissivity of uranium and plutonium carbides at their melting temperatures is in good agreement with experimental data. The obtained results allow to calculate the thermal radiative and thermodynamic properties of liquid and solid uranium and plutonium carbides for any size of samples. Based on the model of Hagen-Rubens and the Wiedemann-Franz law, a new method to determine the thermal conductivity of metals and carbides at the melting points is proposed.

Energy-containing beverages: reproductive hormones and ovarian function in the BioCycle Study123

PubMed Central

Schliep, Karen C; Mumford, Sunni L; Pollack, Anna Z; Perkins, Neil J; Ye, Aijun; Zhang, Cuilin J; Stanford, Joseph B; Porucznik, Christina A; Hammoud, Ahmad O; Wactawski-Wende, Jean

2013-01-01

Background: Energy-containing beverages are widely consumed among premenopausal women, but their association with reproductive hormones is not well understood. Objective: The objective was to assess the association of energy-containing beverages, added sugars, and total fructose intake with reproductive hormones among ovulatory cycles and sporadic anovulation in healthy premenopausal women. Design: Women (n = 259) in the BioCycle Study were followed for up to 2 menstrual cycles; they provided fasting blood specimens during up to 8 visits/cycle and four 24-h dietary recalls/cycle. Results: Women who consumed ≥1 cup (1 cup = 237 mL) sweetened soda/d had 16.3% higher estradiol concentrations compared with women who consumed less sweetened soda (86.5 pg/mL compared with 74.4 pg/mL, P = 0.01) after adjustment for age, BMI, race, dietary factors, and physical activity. Similarly elevated estradiol concentrations were found for ≥1 cup cola/d and noncola soda intake. Neither artificially sweetened soda nor fruit juice intake ≥1 cup/d was significantly associated with reproductive hormones. Added sugar above the average US woman's intake (≥73.2 g/d) or above the 66th percentile in total fructose intake (≥41.5 g/d) was associated with significantly elevated estradiol but not consistently across all models. No associations were found between beverages, added sugars, or total fructose intake and anovulation after multivariate adjustment. Conclusions: Even at moderate consumption amounts, sweetened soda is associated with elevated follicular estradiol concentrations among premenopausal women but does not appear to affect ovulatory function. Further research into the mechanism driving the association between energy-containing beverages and reproductive hormones, and its potential implications for women's health, is warranted. PMID:23364018

Energy-containing beverages: reproductive hormones and ovarian function in the BioCycle Study.

PubMed

Schliep, Karen C; Schisterman, Enrique F; Mumford, Sunni L; Pollack, Anna Z; Perkins, Neil J; Ye, Aijun; Zhang, Cuilin J; Stanford, Joseph B; Porucznik, Christina A; Hammoud, Ahmad O; Wactawski-Wende, Jean

2013-03-01

Energy-containing beverages are widely consumed among premenopausal women, but their association with reproductive hormones is not well understood. The objective was to assess the association of energy-containing beverages, added sugars, and total fructose intake with reproductive hormones among ovulatory cycles and sporadic anovulation in healthy premenopausal women. Women (n = 259) in the BioCycle Study were followed for up to 2 menstrual cycles; they provided fasting blood specimens during up to 8 visits/cycle and four 24-h dietary recalls/cycle. Women who consumed ≥1 cup (1 cup = 237 mL) sweetened soda/d had 16.3% higher estradiol concentrations compared with women who consumed less sweetened soda (86.5 pg/mL compared with 74.4 pg/mL, P = 0.01) after adjustment for age, BMI, race, dietary factors, and physical activity. Similarly elevated estradiol concentrations were found for ≥1 cup cola/d and noncola soda intake. Neither artificially sweetened soda nor fruit juice intake ≥1 cup/d was significantly associated with reproductive hormones. Added sugar above the average US woman's intake (≥73.2 g/d) or above the 66th percentile in total fructose intake (≥41.5 g/d) was associated with significantly elevated estradiol but not consistently across all models. No associations were found between beverages, added sugars, or total fructose intake and anovulation after multivariate adjustment. Even at moderate consumption amounts, sweetened soda is associated with elevated follicular estradiol concentrations among premenopausal women but does not appear to affect ovulatory function. Further research into the mechanism driving the association between energy-containing beverages and reproductive hormones, and its potential implications for women's health, is warranted.

The equilibrium of the reaction catalysed by citrate oxaloacetate-lyase

PubMed Central

Tate, S. S.; Datta, S. P.

1965-01-01

1. A method of preparation and purification of citrate oxaloacetate-lyase (EC 4.1.3.6) from Aerobacter aerogenes is described. 2. The equilibrium of this reaction has been determined at pH 8·4 and 25°. It has been shown that K, i.e. [citrate3−]/[oxaloacetateketo2−][acetate −], is 3·08±0·72, but that Kapp., i.e. [total citrate]/[total oxaloacetate][total acetate], is markedly affected by the initial concentrations of the reactants and magnesium. 3. The free-energy change during the cleavage of citrate has been calculated and compared with data from other sources. 4. The free energy of hydrolysis of acetyl-CoA has been evaluated from the present data. 5. A detailed knowledge of the interactions of the reactants with metal ions has been shown to be important in the calculation of the equilibrium constant and related thermodynamic functions. PMID:14348207

All particle energy spectrum of cosmic rays in 10 to the 15th power - 10 to the 20th power eV region

NASA Technical Reports Server (NTRS)

Krasilnikov, D. D.; Dyakonov, M. N.; Ivanov, A. A.; Kolosov, V. A.; Lischenyuk, F. F.; Sleptsov, I. Y.

1985-01-01

Average estimations of the shower energy components are presented and their sum gives E sub 0 (Rho sub 600) - an average function of the relation of E sub 0 with the shower size parameter Rho sub 600 measured at the Yakutsk extensive air showers (EAS) array. Using this relation to the EAS spectrum obtained at the Akeno and Yakutsk arrays the energy spectrum of the cosmic ray total flux within 15 lg (E sub 0,eV) 20 by the EAS methods is recovered.

Ab-initio calculation for cation vacancy formation energy in anti-fluorite structure

NASA Astrophysics Data System (ADS)

Saleel, V. P. Saleel Ahammad; Chitra, D.; Veluraja, K.; Eithiraj, R. D.

2018-04-01

Lithium oxide (Li2O) has been suggested as a suitable breeder blanket material for fusion reactors. Li+ vacancies are created by neutron irradiation, forming bulk defect complex whose extra character is experimentally unclear. We present a theoretical study of Li2O using density functional theory (DFT) with a plane-wave basis set. The generalized gradient approximation (GGA) and local-density approximation (LDA) were used for exchange and correlation. Here we address the total energy for defect free, cation defect, cation vacancy and vacancy formation energy in Li2O crystal in anti-fluorite structure.

Density-Decomposed Orbital-Free Density Functional Theory for Covalent Systems and Application to Li-Si alloys

NASA Astrophysics Data System (ADS)

Xia, Junchao; Carter, Emily

2014-03-01

We propose a density decomposition scheme using a Wang-Govind-Carter (WGC)-based kinetic energy density functional (KEDF) to accurately and efficiently simulate covalent systems within orbital-free (OF) density functional theory (DFT). By using a local, density-dependent scale function, the total density is decomposed into a localized density within covalent bond regions and a flattened delocalized density, with the former described by semilocal KEDFs and the latter treated by the WGC KEDF. The new model predicts reasonable equilibrium volumes, bulk moduli, and phase ordering energies for various semiconductors compared to Kohn-Sham (KS) DFT benchmarks. The surface energy of Si(100) also agrees well with KSDFT. We further apply the model to study mechanical properties of Li-Si alloys, which have been recently recognized as a promising candidate for next-generation anodes of Li-ion batteries with outstanding capacity. We study multiple crystalline Li-Si alloys. The WGCD KEDF predicts accurate cell lattice vectors, equilibrium volumes, elastic moduli, electron densities, alloy formation and Li adsorption energies. Because of its quasilinear scaling, coupled with the level of accuracy shown here, OFDFT appears quite promising for large-scale simulation of such materials phenomena. Office of Naval Research, National Science Foundation, Tigress High Performance Computing Center.

Defense, Space, and Energy Account for Most of Record Increase in Federal R&D Total in FY 1976. Science Resources Studies Highlights, August 25, 1975.

ERIC Educational Resources Information Center

National Science Foundation, Washington, DC. Div. of Science Resources Studies.

Presented are data taken from a forthcoming report, An Analysis of Federal Research and Development (R&D) Funding by Function, Fiscal Years 1969-76. The 14 function categories were chosen to make visible the most important R&D objectives in the 1976 budget. Data are additive to 100 percent, and thus each program appears only under a…

Scaling of charged particle production in d+Au collisions at √(sNN)=200GeV

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wysłouch, B.; Zhang, J.

2005-09-01

The measured pseudorapidity distributions of primary charged particles over a wide pseudorapidity range of |η|≤5.4 and integrated charged particle multiplicities in d+Au collisions at √(sNN)=200GeV are presented as a function of collision centrality. The longitudinal features of d+Au collisions at √(sNN)=200GeV are found to be very similar to those seen in p+A collisions at lower energies. The total multiplicity of charged particles is found to scale with the total number of participants according to NdAuch=1/2Nppch, and the energy dependence of the density of charged particles produced in the fragmentation region exhibits extended longitudinal scaling.

Force-field parameters of the Psi and Phi around glycosidic bonds to oxygen and sulfur atoms.

PubMed

Saito, Minoru; Okazaki, Isao

2009-12-01

The Psi and Phi torsion angles around glycosidic bonds in a glycoside chain are the most important determinants of the conformation of a glycoside chain. We determined force-field parameters for Psi and Phi torsion angles around a glycosidic bond bridged by a sulfur atom, as well as a bond bridged by an oxygen atom as a preparation for the next study, i.e., molecular dynamics free energy calculations for protein-sugar and protein-inhibitor complexes. First, we extracted the Psi or Phi torsion energy component from a quantum mechanics (QM) total energy by subtracting all the molecular mechanics (MM) force-field components except for the Psi or Phi torsion angle. The Psi and Phi energy components extracted (hereafter called "the remaining energy components") were calculated for simple sugar models and plotted as functions of the Psi and Phi angles. The remaining energy component curves of Psi and Phi were well represented by the torsion force-field functions consisting of four and three cosine functions, respectively. To confirm the reliability of the force-field parameters and to confirm its compatibility with other force-fields, we calculated adiabatic potential curves as functions of Psi and Phi for the model glycosides by adopting the Psi and Phi force-field parameters obtained and by energetically optimizing other degrees of freedom. The MM potential energy curves obtained for Psi and Phi well represented the QM adiabatic curves and also these curves' differences with regard to the glycosidic oxygen and sulfur atoms. Our Psi and Phi force-fields of glycosidic oxygen gave MM potential energy curves that more closely represented the respective QM curves than did those of the recently developed GLYCAM force-field. (c) 2009 Wiley Periodicals, Inc.

Roothaan-Hartree-Fock ground-state atomic wave functions: Slater-type orbital expansions and expectation values for Z = 2-54

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunge, C.F.; Barrientos, J.A.; Bunge, A.V.

1993-01-01

Roothaan-Hartree-Fock orbitals expressed in a Slater-type basis are reported for the ground states of He through Xe. Energy accuracy ranges between 8 and 10 significant figures, reducing by between 21 and 2,770 times the energy errors of the previous such compilation (E. Clementi and C. Roetti, Atomic Data and Nuclear Data Tables 14, 177, 1974). For each atom, the total energy, kinetic energy, potential energy, virial ratio, electron density at the nucleus, and the Kato cusp are given together with radial expectation values [l angle]r[sup n][r angle] with n from [minus]3 to 2 for each orbital, orbital energies, and orbitalmore » expansion coefficients. 29 refs., 1 tab.« less

The zero-multipole summation method for estimating electrostatic interactions in molecular dynamics: analysis of the accuracy and application to liquid systems.

PubMed

Fukuda, Ikuo; Kamiya, Narutoshi; Nakamura, Haruki

2014-05-21

In the preceding paper [I. Fukuda, J. Chem. Phys. 139, 174107 (2013)], the zero-multipole (ZM) summation method was proposed for efficiently evaluating the electrostatic Coulombic interactions of a classical point charge system. The summation takes a simple pairwise form, but prevents the electrically non-neutral multipole states that may artificially be generated by a simple cutoff truncation, which often causes large energetic noises and significant artifacts. The purpose of this paper is to judge the ability of the ZM method by investigating the accuracy, parameter dependencies, and stability in applications to liquid systems. To conduct this, first, the energy-functional error was divided into three terms and each term was analyzed by a theoretical error-bound estimation. This estimation gave us a clear basis of the discussions on the numerical investigations. It also gave a new viewpoint between the excess energy error and the damping effect by the damping parameter. Second, with the aid of these analyses, the ZM method was evaluated based on molecular dynamics (MD) simulations of two fundamental liquid systems, a molten sodium-chlorine ion system and a pure water molecule system. In the ion system, the energy accuracy, compared with the Ewald summation, was better for a larger value of multipole moment l currently induced until l ≲ 3 on average. This accuracy improvement with increasing l is due to the enhancement of the excess-energy accuracy. However, this improvement is wholly effective in the total accuracy if the theoretical moment l is smaller than or equal to a system intrinsic moment L. The simulation results thus indicate L ∼ 3 in this system, and we observed less accuracy in l = 4. We demonstrated the origins of parameter dependencies appearing in the crossing behavior and the oscillations of the energy error curves. With raising the moment l we observed, smaller values of the damping parameter provided more accurate results and smoother behaviors with respect to cutoff length were obtained. These features can be explained, on the basis of the theoretical error analyses, such that the excess energy accuracy is improved with increasing l and that the total accuracy improvement within l ⩽ L is facilitated by a small damping parameter. Although the accuracy was fundamentally similar to the ion system, the bulk water system exhibited distinguishable quantitative behaviors. A smaller damping parameter was effective in all the practical cutoff distance, and this fact can be interpreted by the reduction of the excess subset. A lower moment was advantageous in the energy accuracy, where l = 1 was slightly superior to l = 2 in this system. However, the method with l = 2 (viz., the zero-quadrupole sum) gave accurate results for the radial distribution function. We confirmed the stability in the numerical integration for MD simulations employing the ZM scheme. This result is supported by the sufficient smoothness of the energy function. Along with the smoothness, the pairwise feature and the allowance of the atom-based cutoff mode on the energy formula lead to the exact zero total-force, ensuring the total-momentum conservations for typical MD equations of motion.

The zero-multipole summation method for estimating electrostatic interactions in molecular dynamics: Analysis of the accuracy and application to liquid systems

NASA Astrophysics Data System (ADS)

Fukuda, Ikuo; Kamiya, Narutoshi; Nakamura, Haruki

2014-05-01

In the preceding paper [I. Fukuda, J. Chem. Phys. 139, 174107 (2013)], the zero-multipole (ZM) summation method was proposed for efficiently evaluating the electrostatic Coulombic interactions of a classical point charge system. The summation takes a simple pairwise form, but prevents the electrically non-neutral multipole states that may artificially be generated by a simple cutoff truncation, which often causes large energetic noises and significant artifacts. The purpose of this paper is to judge the ability of the ZM method by investigating the accuracy, parameter dependencies, and stability in applications to liquid systems. To conduct this, first, the energy-functional error was divided into three terms and each term was analyzed by a theoretical error-bound estimation. This estimation gave us a clear basis of the discussions on the numerical investigations. It also gave a new viewpoint between the excess energy error and the damping effect by the damping parameter. Second, with the aid of these analyses, the ZM method was evaluated based on molecular dynamics (MD) simulations of two fundamental liquid systems, a molten sodium-chlorine ion system and a pure water molecule system. In the ion system, the energy accuracy, compared with the Ewald summation, was better for a larger value of multipole moment l currently induced until l ≲ 3 on average. This accuracy improvement with increasing l is due to the enhancement of the excess-energy accuracy. However, this improvement is wholly effective in the total accuracy if the theoretical moment l is smaller than or equal to a system intrinsic moment L. The simulation results thus indicate L ˜ 3 in this system, and we observed less accuracy in l = 4. We demonstrated the origins of parameter dependencies appearing in the crossing behavior and the oscillations of the energy error curves. With raising the moment l we observed, smaller values of the damping parameter provided more accurate results and smoother behaviors with respect to cutoff length were obtained. These features can be explained, on the basis of the theoretical error analyses, such that the excess energy accuracy is improved with increasing l and that the total accuracy improvement within l ⩽ L is facilitated by a small damping parameter. Although the accuracy was fundamentally similar to the ion system, the bulk water system exhibited distinguishable quantitative behaviors. A smaller damping parameter was effective in all the practical cutoff distance, and this fact can be interpreted by the reduction of the excess subset. A lower moment was advantageous in the energy accuracy, where l = 1 was slightly superior to l = 2 in this system. However, the method with l = 2 (viz., the zero-quadrupole sum) gave accurate results for the radial distribution function. We confirmed the stability in the numerical integration for MD simulations employing the ZM scheme. This result is supported by the sufficient smoothness of the energy function. Along with the smoothness, the pairwise feature and the allowance of the atom-based cutoff mode on the energy formula lead to the exact zero total-force, ensuring the total-momentum conservations for typical MD equations of motion.

Analysis of Different Fragmentation Strategies on a Variety of Large Peptides: Implementation of a Low Level of Theory in Fragment-Based Methods Can Be a Crucial Factor.

PubMed

Saha, Arjun; Raghavachari, Krishnan

2015-05-12

We have investigated the performance of two classes of fragmentation methods developed in our group (Molecules-in-Molecules (MIM) and Many-Overlapping-Body (MOB) expansion), to reproduce the unfragmented MP2 energies on a test set composed of 10 small to large biomolecules. They have also been assessed to recover the relative energies of different motifs of the acetyl(ala)18NH2 system. Performance of different bond-cutting environments and the use of Hartree-Fock and different density functionals (as a low level of theory) in conjunction with the fragmentation strategies have been analyzed. Our investigation shows that while a low level of theory (for recovering long-range interactions) may not be necessary for small peptides, it provides a very effective strategy to accurately reproduce the total and relative energies of larger peptides such as the different motifs of the acetyl(ala)18NH2 system. Employing M06-2X as the low level of theory, the calculated mean total energy deviation (maximum deviation) in the total MP2 energies for the 10 molecules in the test set at MIM(d=3.5Å), MIM(η=9), and MOB(d=5Å) are 1.16 (2.31), 0.72 (1.87), and 0.43 (2.02) kcal/mol, respectively. The excellent performance suggests that such fragment-based methods should be of general use for the computation of accurate energies of large biomolecular systems.

First-principles photoemission spectroscopy in DNA and RNA nucleobases from Koopmans-compliant functionals

NASA Astrophysics Data System (ADS)

Nguyen, Ngoc Linh; Borghi, Giovanni; Ferretti, Andrea; Marzari, Nicola

The determination of spectral properties of the DNA and RNA nucleobases from first principles can provide theoretical interpretation for experimental data, but requires complex electronic-structure formulations that fall outside the domain of applicability of common approaches such as density-functional theory. In this work, we show that Koopmans-compliant functionals, constructed to enforce piecewise linearity in energy functionals with respect to fractional occupation-i.e., with respect to charged excitations-can predict not only frontier ionization potentials and electron affinities of the nucleobases with accuracy comparable or superior with that of many-body perturbation theory and high-accuracy quantum chemistry methods, but also the molecular photoemission spectra are shown to be in excellent agreement with experimental ultraviolet photoemsision spectroscopy data. The results highlight the role of Koopmans-compliant functionals as accurate and inexpensive quasiparticle approximations to the spectral potential, which transform DFT into a novel dynamical formalism where electronic properties, and not only total energies, can be correctly accounted for.

Electronic structure investigation of neutral titanium oxide molecules TixOy

NASA Astrophysics Data System (ADS)

Jeong, K. S.; Chang, Ch; Sedlmayr, E.; Sülzle, D.

2000-09-01

Electronic and structural properties of energetically low-lying isomers of isolated TixOy (x = 1-6, y = 1-12) molecular systems have been investigated by density functional theoretical methods. A variety of stationary points are thoroughly characterized. We report total cluster energies, equilibrium geometries and harmonic vibrational wavenumbers.

Algorithm for calculations of asymptotic nuclear coefficients using phase-shift data for charged-particle scattering

NASA Astrophysics Data System (ADS)

Orlov, Yu. V.; Irgaziev, B. F.; Nabi, Jameel-Un

2017-08-01

A new algorithm for the asymptotic nuclear coefficients calculation, which we call the Δ method, is proved and developed. This method was proposed by Ramírez Suárez and Sparenberg (arXiv:1602.04082.) but no proof was given. We apply it to the bound state situated near the channel threshold when the Sommerfeld parameter is quite large within the experimental energy region. As a result, the value of the conventional effective-range function Kl(k2) is actually defined by the Coulomb term. One of the resulting effects is a wrong description of the energy behavior of the elastic scattering phase shift δl reproduced from the fitted total effective-range function Kl(k2) . This leads to an improper value of the asymptotic normalization coefficient (ANC) value. No such problem arises if we fit only the nuclear term. The difference between the total effective-range function and the Coulomb part at real energies is the same as the nuclear term. Then we can proceed using just this Δ method to calculate the pole position values and the ANC. We apply it to the vertices 4He+12C ↔16O and 3He+4He↔7Be . The calculated ANCs can be used to find the radiative capture reaction cross sections of the transfers to the 16O bound final states as well as to the 7Be.

a New Phenomenological Formula for Ground-State Binding Energies

NASA Astrophysics Data System (ADS)

Gangopadhyay, G.

A phenomenological formula based on liquid drop model has been proposed for ground-state binding energies of nuclei. The effect due to bunching of single particle levels has been incorporated through a term resembling the one-body Hamiltonian. The effect of n-p interaction has been included through a function of valence nucleons. A total of 50 parameters has been used in the present calculation. The root mean square (r.m.s.) deviation for the binding energy values for 2140 nuclei comes out to be 0.376 MeV, and that for 1091 alpha decay energies is 0.284 MeV. The correspondence with the conventional liquid drop model is discussed.

Higher Order Multipole Potentials and Electrostatic Screening Effects on Cohesive Energy and Bulk Modulus of Metallic Nanoparticles

NASA Astrophysics Data System (ADS)

Barakat, T.

2011-12-01

Higher order multipole potentials and electrostatic screening effects are introduced to incorporate the dangling bonds on the surface of a metallic nanopaticle and to modify the coulomb like potential energy terms, respectively. The total interaction energy function for any metallic nanoparticle is represented in terms of two- and three-body potentials. The two-body part is described by dipole-dipole interaction potential, and in the three-body part, triple-dipole (DDD) and dipole-dipole-quadrupole (DDQ) terms are included. The size-dependent cohesive energy and bulk modulus are observed to decrease with decreasing sizes, a result which is in good agreement with the experimental values of Mo and W nanoparticles.

Simultaneous analytical optimization of variational parameters in Gaussian-type functions with full configuration interaction of multicomponent molecular orbital method by elimination of translational and rotational motions: application to isotopomers of the hydrogen molecule.

PubMed

Ishimoto, Takayoshi; Tachikawa, Masanori; Nagashima, Umpei

2008-04-28

We have extended the multicomponent molecular orbital (MCMO) method to the full-configuration interaction (full-CI) fully variational molecular orbital method by elimination of translational and rotational motion components from total Hamiltonian. In the MCMO scheme, the quantum effects of protons and deuterons as well as electrons can be directly taken into account. All variational parameters in the full-CI scheme, i.e., exponents and centers (alpha and R) in the Gaussian-type function (GTF) basis set as well as the CI coefficients, are simultaneously optimized by using their analytical gradients. The total energy of the H(2) molecule calculated using the electronic [6s3p2d1f] and nuclear [1s1p1d1f] GTFs is -1.161 726 hartree, which can be compared to the energy of -1.164 025 hartree reported using a 512 term-explicitly correlated GTF calculation. Although the d- and f-type nuclear GTFs contribute to the improvement of energy convergence, the convergence of electron-nucleus correlation energy is slower than that of electron-electron one. The nuclear wave functions are delocalized due to the electron-nucleus correlation effect compared to the result of Hartree-Fock level of MCMO method. In addition, the average internuclear distances of all diatomic molecules are within 0.001 A of the previously reported experimental results. The dipole moment of the HD molecule estimated by our method is 8.4 x 10(-4) D, which is in excellent agreement with the experimental result of (8-10) x 10(-4) D.

Influence of Parameters of a Reactive Interatomic Potential on the Properties of Saturated Hydrocarbons

DTIC Science & Technology

2017-01-01

Methodology 3 2.1 Modified Embedded-Atom Method Theory 3 2.1.1 Embedding Energy Function 3 2.1.2 Screening Factor 8 2.1.3 Modified Embedded-Atom...Simulation Methodology 2.1 Modified Embedded-Atom Method Theory In the EAM and MEAM formalisms1,2,5 the total energy of a system of atoms (Etot) is...An interatomic potential for saturated hydrocarbons using the modified embedded-atom method (MEAM), a semiempirical many-body potential based on

Energy anisotropy as a function of the direction of spin magnetization for a doublet system

NASA Astrophysics Data System (ADS)

Cherry, Peter J.; Malkin, Vladimir G.; Malkina, Olga L.; Asher, James R.

2016-11-01

This manuscript describes new phenomena that currently are not taken into account in both experimental EPR spectra interpretations and quantum chemical calculations of EPR parameters. This article presents an argument, with evidence, against the common belief that in the absence of an external magnetic field the total energy of a doublet system is independent of the spin orientation. Consequences of this phenomenon for interpretation of EPR experimental studies as well as for quantum chemical calculations of EPR parameters are discussed.

Energy Systems Integration: Data Call -- Become a Data Partner

DOE Office of Scientific and Technical Information (OSTI.GOV)

2017-01-01

This project aims to advance the understanding of costs associated with integrating PV onto the electric power distribution system while maintaining reliable grid operations. We have developed a bottom-up framework for calculating these costs as a function of PV penetration levels on specific feeders. This framework will used to inform and improve utility planning decisions, increase the transparency and speed associated with the interconnection process, and provide policymakers with more information on the total cost of energy from PV.

Low energy electron transport in furfural

NASA Astrophysics Data System (ADS)

Lozano, Ana I.; Krupa, Kateryna; Ferreira da Silva, Filipe; Limão-Vieira, Paulo; Blanco, Francisco; Muñoz, Antonio; Jones, Darryl B.; Brunger, Michael J.; García, Gustavo

2017-09-01

We report on an initial investigation into the transport of electrons through a gas cell containing 1 mTorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulation, our preferred energy loss distribution function is presented and discussed.

Remarks on Heisenberg-Euler-type electrodynamics

NASA Astrophysics Data System (ADS)

Kruglov, S. I.

2017-05-01

We consider Heisenberg-Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg-Euler electrodynamics is a particular case of this model. Corrections to Coulomb’s law at r →∞ are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at r →∞. Corrections to the Reissner-Nordström solution are obtained.

Polarized heavy quarkonium production in the color evaporation model

DOE PAGES

Cheung, Vincent; Vogt, Ramona

2017-04-14

Here, we explore polarized heavy quarkonium production using the color evaporation model at leading order. We present the polarized to total yield ratio as a function of center of mass energy and rapidity in p+p collisions. At energies far above the Q¯Q production threshold, we find charmonium and bottomonium production to be longitudinally polarized (J z = 0). The quarkonium states are also longitudinally polarized at central rapidity, becoming transversely polarized (J z = ±1) at the most forward rapidities.

A proposed approach to the application of nonlinear irreversible thermodynamics to fracture in composite materials

NASA Technical Reports Server (NTRS)

Lindenmeyer, P. H.

1983-01-01

The fracture criteria upon which most fracture mechanics is based involves an energy balance that is not appropriate for the fracture mechanics of viscoelastic materials such as polymer matrix composites. A more appropriate criterion based upon nonequilibrium thermodynamics and involving a power balance rather than an energy balance is proposed. This crierion is based upon a reformulation of the second law of thermodynamics which focuses attention on the total Legendre transform of energy expressed as a functional over time and space. This excess energy functional can be shown to be equivalent to the Rice J integral if the only irreversible process is the propogation of a single crack completely through the thickness of the specimen and if the crack propogation is assured to be independent of time. For the more general case of more than one crack in a viscoelastic medium integration over both time and space is required. Two experimentally measurable parameters are proposed which should permit the evaluation of this more general fracture criterion.

Functional reconstruction of total lower lip defects using innervated gracilis flap in the setting of high-energy ballistic injury to the lower face: preliminary report.

PubMed

Gurunluoglu, Raffi; Glasgow, Mark; Williams, Susan A; Gurunluoglu, Aslin; Antrobus, Jarod; Eusterman, Vincent

2012-10-01

Reconstruction of total full-thickness lower lip defects combined with extensive composite mandibular defects particularly in the setting of close-range high-energy ballistic injury presents a formidable challenge for the reconstructive plastic surgeon. While the fibular flap has been widely accepted for its usefulness in the reconstruction of composite mandibular defects, to date, there is no definitive widely established method of total lower lip reconstruction. The article presents authors' approach using innervated gracilis muscle flap for total lower lip reconstruction in the setting of high-energy gunshot injuries to the face. Three patients underwent composite mandibular defect reconstruction using fibular osteocutaneous flap and functional lower lip reconstruction using innervated gracilis muscle flap. Lip lining was reconstructed using the skin paddle of the fibular flap. The external surface of the gracilis muscle was skin-grafted. Facial artery myomucosal flap provided vermilion reconstruction in two patients. All fibular (n=3) and gracilis flap transfers (n=3) were viable. An electromyographic study at 1 year postoperatively demonstrated successful re-innervation of the gracilis muscle. Starting at about 10 weeks postoperatively, patients exhibited voluntary lip movements and oral competence. In addition, all patients achieved near-normal speech, evidence of recovered protective sensitivity and satisfactory appearance. The mean follow-up was 16.1 months. Our preliminary report in three patients demonstrated that innervated gracilis muscle transfer combined with fibular flap provides a successful reconstruction of extensive composite mandibular and total lower lip defects resulting from gunshot injuries to the face. Oral continence was achieved by combination of regained tonicity and voluntary movement of the gracilis muscle following re-innervation and assistance of the cheek muscles on the gracilis muscle. The described technique was reliable and the results were promising. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Penalized weighted least-squares approach for multienergy computed tomography image reconstruction via structure tensor total variation regularization.

PubMed

Zeng, Dong; Gao, Yuanyuan; Huang, Jing; Bian, Zhaoying; Zhang, Hua; Lu, Lijun; Ma, Jianhua

2016-10-01

Multienergy computed tomography (MECT) allows identifying and differentiating different materials through simultaneous capture of multiple sets of energy-selective data belonging to specific energy windows. However, because sufficient photon counts are not available in each energy window compared with that in the whole energy window, the MECT images reconstructed by the analytical approach often suffer from poor signal-to-noise and strong streak artifacts. To address the particular challenge, this work presents a penalized weighted least-squares (PWLS) scheme by incorporating the new concept of structure tensor total variation (STV) regularization, which is henceforth referred to as 'PWLS-STV' for simplicity. Specifically, the STV regularization is derived by penalizing higher-order derivatives of the desired MECT images. Thus it could provide more robust measures of image variation, which can eliminate the patchy artifacts often observed in total variation (TV) regularization. Subsequently, an alternating optimization algorithm was adopted to minimize the objective function. Extensive experiments with a digital XCAT phantom and meat specimen clearly demonstrate that the present PWLS-STV algorithm can achieve more gains than the existing TV-based algorithms and the conventional filtered backpeojection (FBP) algorithm in terms of both quantitative and visual quality evaluations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Iterative image reconstruction for multienergy computed tomography via structure tensor total variation regularization

NASA Astrophysics Data System (ADS)

Zeng, Dong; Bian, Zhaoying; Gong, Changfei; Huang, Jing; He, Ji; Zhang, Hua; Lu, Lijun; Feng, Qianjin; Liang, Zhengrong; Ma, Jianhua

2016-03-01

Multienergy computed tomography (MECT) has the potential to simultaneously offer multiple sets of energy- selective data belonging to specific energy windows. However, because sufficient photon counts are not available in the specific energy windows compared with that in the whole energy window, the MECT images reconstructed by the analytical approach often suffer from poor signal-to-noise (SNR) and strong streak artifacts. To eliminate this drawback, in this work we present a penalized weighted least-squares (PWLS) scheme by incorporating the new concept of structure tensor total variation (STV) regularization to improve the MECT images quality from low-milliampere-seconds (low-mAs) data acquisitions. Henceforth the present scheme is referred to as `PWLS- STV' for simplicity. Specifically, the STV regularization is derived by penalizing the eigenvalues of the structure tensor of every point in the MECT images. Thus it can provide more robust measures of image variation, which can eliminate the patchy artifacts often observed in total variation regularization. Subsequently, an alternating optimization algorithm was adopted to minimize the objective function. Experiments with a digital XCAT phantom clearly demonstrate that the present PWLS-STV algorithm can achieve more gains than the existing TV-based algorithms and the conventional filtered backpeojection (FBP) algorithm in terms of noise-induced artifacts suppression, resolution preservation, and material decomposition assessment.

X-Ray Spectro-Polarimetry with Photoelectric Polarimeters

NASA Technical Reports Server (NTRS)

Strohmayer, T. E.

2017-01-01

We derive a generalization of forward fitting for X-ray spectroscopy to include linear polarization of X-ray sources, appropriate for the anticipated next generation of space-based photoelectric polarimeters. We show that the inclusion of polarization sensitivity requires joint fitting to three observed spectra, one for each of the Stokes parameters, I(E), U(E), and Q(E). The equations for StokesI (E) (the total intensity spectrum) are identical to the familiar case with no polarization sensitivity, and for which the model-predicted spectrum is obtained by a convolution of the source spectrum, F (E), with the familiar energy response function,(E) R(E,E), where (E) and R(E,E) are the effective area and energy redistribution matrix, respectively. In addition to the energy spectrum, the two new relations for U(E) and Q(E) include the source polarization fraction and position angle versus energy, a(E), and 0(E), respectively, and the model-predicted spectra for these relations are obtained by a convolution with the modulated energy response function, (E)(E) R(E,E), where(E) is the energy-dependent modulation fraction that quantifies a polarimeters angular response to 100 polarized radiation. We present results of simulations with response parameters appropriate for the proposed PRAXyS Small Explorer observatory to illustrate the procedures and methods, and we discuss some aspects of photoelectric polarimeters with relevance to understanding their calibration and operation.

Effects of dietary sweet potato leaf meal on the growth, non-specific immune responses, total phenols and antioxidant capacity in channel catfish (Ictalurus punctatus).

PubMed

Lochmann, Rebecca T; Islam, Shahidul; Phillips, Harold; Adam, Zelalem; Everette, Jace

2013-04-01

Traditional energy sources in catfish diets have become costly, and economical alternatives are needed. Sweet potato leaves are underutilised agricultural by-products that provide energy and substantial amounts of phenols, which affect animal and human health. There is little information on the effects of these compounds on catfish, or the capacity of catfish to accumulate dietary phenols. Catfish enriched with phenols have marketing potential as functional foods. This study investigated the effects of diets with sweet potato leaf meal (SPLM) on growth performance, health and total phenolic compounds in catfish. SPLM was substituted for wheat middlings in three diets fed to groups of juvenile catfish for 10 weeks. Weight gain, feed conversion, survival, alternative complement activity and lysozyme activity were similar among diets. Haematocrit was lower in fish fed diets with SPLM, but within the normal range. Total phenols and antioxidant capacity in the whole body were similar among treatments. SPLM was an effective energy source for catfish up to the maximum level tested (230 g kg(-1) diet). SPLM did not enhance total phenols in catfish, but there were no apparent antinutritional effects of the meal on catfish growth, health or survival. © 2012 Society of Chemical Industry.

Exchange coupling and magnetic anisotropy in a family of bipyrimidyl radical-bridged dilanthanide complexes: density functional theory and ab initio calculations.

PubMed

Zhang, Yi-Quan; Luo, Cheng-Lin; Zhang, Qiang

2014-05-05

The origin of the magnetic anisotropy energy barriers in a series of bpym(-) (bpym = 2,2'-bipyrimidine) radical-bridged dilanthanide complexes [(Cp*2Ln)2(μ-bpym)](+) [Cp* = pentamethylcyclopentadienyl; Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Er(III) (5)] has been explored using density functional theory (DFT) and ab initio methods. DFT calculations show that the exchange coupling between the two lanthanide ions for each complex is very weak, but the antiferromagnetic Ln-bpym(-) couplings are strong. Ab initio calculations show that the effective energy barrier of 2 or 3 mainly comes from the contribution of a single Tb(III) or Dy(III) fragment, which is only about one third of a single Ln energy barrier. For 4 or 5, however, both of the two Ho(III) or Er(III) fragments contribute to the total energy barrier. Thus, it is insufficient to only increase the magnetic anisotropy energy barrier of a single Ln ion, while enhancing the Ln-bpym(-) couplings is also very important. Copyright © 2014 Wiley Periodicals, Inc.

Hydrogen incorporation into BN fullerene-like nanostructures: A first-principles study

NASA Astrophysics Data System (ADS)

Ganji, M. D.; Abbaszadeh, B.; Ahaz, B.

2011-10-01

We performed density functional theory calculations to investigate the possibility of formation of endohedrally H@(BN) n-fullerene ( n: 24, 36, 60) and H@C 60 complexes for potential applications in solid-state quantum-computers. Spin-polarized approach within the generalized gradient approximation with the Perdew-Burke-Ernzerhof functional was used for the total energies and structural relaxation calculations. The calculated binding energies show that H atom being incorporated into B 60N 60 nanocage can form most stable complexes while the B 24N 24 and C 60 nanocages might form unstable complex with positive binding energy. We have also examined the penetration of an H atom into the respective nanocages and the calculated barrier energies indicate that the H atom prefers to penetrate into the B 24N 24 and B 60N 60 nanocages with barrier energy of about 0.47 eV (10.84 kcal/mol). Furthermore the binding characteristic is rationalized by analyzing the electronic structures. Our findings reveal that the B 60N 60 nanocage has fascinating potential application in future solid-state quantum-computers.

Ab initio intermolecular potential energy surface for the CO2—N2 system and related thermophysical properties

NASA Astrophysics Data System (ADS)

Crusius, Johann-Philipp; Hellmann, Robert; Castro-Palacio, Juan Carlos; Vesovic, Velisa

2018-06-01

A four-dimensional potential energy surface (PES) for the interaction between a rigid carbon dioxide molecule and a rigid nitrogen molecule was constructed based on quantum-chemical ab initio calculations up to the coupled-cluster level with single, double, and perturbative triple excitations. Interaction energies for a total of 1893 points on the PES were calculated using the counterpoise-corrected supermolecular approach and basis sets of up to quintuple-zeta quality with bond functions. The interaction energies were extrapolated to the complete basis set limit, and an analytical site-site potential function with seven sites for carbon dioxide and five sites for nitrogen was fitted to the interaction energies. The CO2—N2 cross second virial coefficient as well as the dilute gas shear viscosity, thermal conductivity, and binary diffusion coefficient of CO2—N2 mixtures were calculated for temperatures up to 2000 K to validate the PES and to provide reliable reference values for these important properties. The calculated values are in very good agreement with the best experimental data.

B+ L violation at colliders and new physics

NASA Astrophysics Data System (ADS)

Cerdeño, David G.; Reimitz, Peter; Sakurai, Kazuki; Tamarit, Carlos

2018-04-01

Chiral electroweak anomalies predict baryon ( B) and lepton ( L) violating fermion interactions, which can be dressed with large numbers of Higgs and gauge bosons. The estimation of the total B + L-violating rate from an initial two-particle state — potentially observable at colliders — has been the subject of an intense discussion, mainly centered on the resummation of boson emission, which is believed to contribute to the cross-section with an exponential function of the energy, yet with an exponent (the "holy-grail" function) which is not fully known in the energy range of interest. In this article we focus instead on the effect of fermions beyond the Standard-Model (SM) in the polynomial contributions to the rate. It is shown that B + L processes involving the new fermions have a polynomial contribution that can be several orders of magnitude greater than in the SM, for high centre-of-mass energies and light enough masses. We also present calculations that hint at a simple dependence of the holy grail function on the heavy fermion masses. Thus, if anomalous B + L violating interactions are ever detected at high-energy colliders, they could be associated with new physics.

Physiological and psychological effects of testosterone during severe energy deficit and recovery: A study protocol for a randomized, placebo-controlled trial for Optimizing Performance for Soldiers (OPS).

PubMed

Pasiakos, Stefan M; Berryman, Claire E; Karl, J Philip; Lieberman, Harris R; Orr, Jeb S; Margolis, Lee M; Caldwell, John A; Young, Andrew J; Montano, Monty A; Evans, William J; Vartanian, Oshin; Carmichael, Owen T; Gadde, Kishore M; Harris, Melissa; Rood, Jennifer C

2017-07-01

The physiological consequences of severe energy deficit include hypogonadism and the loss of fat-free mass. Prolonged energy deficit also impacts physical performance, mood, attentiveness, and decision-making capabilities. This study will determine whether maintaining a eugonadal state during severe, sustained energy deficit attenuates physiological decrements and maintains mental performance. This study will also assess the effects of normalizing testosterone levels during severe energy deficit and recovery on gut health and appetite regulation. Fifty physically active men will participate in a 3-phase, randomized, placebo-controlled study. After completing a 14-d, energy-adequate, diet acclimation phase (protein: 1.6g∙kg -1 ∙d -1 ; fat: 30% total energy intake), participants will be randomized to undergo a 28-d, 55% energy deficit phase with (DEF+TEST: 200mg testosterone enanthate per week) or without (DEF) exogenous testosterone. Diet and physical activity will be rigorously controlled. Recovery from the energy deficit (ad libitum diet, no testosterone) will be assessed until body mass has been recovered within ±2.5% of initial body mass. Body composition, stable isotope methodologies, proteomics, muscle biopsies, whole-room calorimetry, molecular biology, activity/sleep monitoring, personality and cognitive function assessments, functional MRI, and comprehensive biochemistries will be used to assess physiological and psychological responses to energy restriction and recovery feeding while volunteers are in an expected hypogonadal versus eugonadal state. The Optimizing Performance for Soldiers (OPS) study aims to determine whether preventing hypogonadism will mitigate declines in physical and mental function that typically occur during prolonged energy deficit, and the efficacy of testosterone replacement on recovery from severe underfeeding. NCT02734238. Copyright © 2017. Published by Elsevier Inc.

Molecular structure, vibrational spectra, NBO analysis, first hyperpolarizability, and HOMO-LUMO studies of 2-amino-4-hydroxypyrimidine by density functional method

NASA Astrophysics Data System (ADS)

Jeyavijayan, S.

2015-04-01

This study is a comparative analysis of FTIR and FT-Raman spectra of 2-amino-4-hydroxypyrimidine. The total energies of different conformations have been obtained from DFT (B3LYP) method with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The barrier of planarity between the most stable and planar form is also predicted. The molecular structure, vibrational wavenumbers, infrared intensities, Raman scattering activities were calculated for the molecule using the B3LYP density functional theory (DFT) method. The computed values of frequencies are scaled using multiple scaling factors to yield good coherence with the observed values. Reliable vibrational assignments were made on the basis of total energy distribution (TED) along with scaled quantum mechanical (SQM) method. The stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Non-linear properties such as electric dipole moment (μ), polarizability (α), and hyperpolarizability (β) values of the investigated molecule have been computed using B3LYP quantum chemical calculation. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Besides, molecular electrostatic potential (MEP), Mulliken's charges analysis, and several thermodynamic properties were performed by the DFT method.

Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission

NASA Astrophysics Data System (ADS)

Lestone, J. P.

2016-01-01

A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of 235U and from spontaneous fission of 252Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.

First-principles study of the structural and elastic properties of AuxV1-x and AuxNb1-x alloys

NASA Astrophysics Data System (ADS)

Al-Zoubi, N.

2018-04-01

Ab initio total energy calculations, based on the Exact Muffin-Tin Orbitals (EMTO) method in combination with the coherent potential approximation (CPA), are used to calculate the total energy of AuxV1-x and AuxNb1-x random alloys along the Bain path that connects the body-centred cubic (bcc) and face-centred cubic (fcc) structures as a function of composition x (0 ≤ x ≤ 1). The equilibrium Wigner-Seitz radius and the elastic properties of both systems are determined as a function of composition. Our theoretical prediction in case of pure elements (x = 0 or x = 1) are in good agreement with the available experimental data. For the Au-V system, the equilibrium Wigner-Seitz radius increase as x increases, while for the Au-Nb system, the equilibrium Wigner-Seitz radius is almost constant. The bulk modulus B and C44 for both alloys exhibit nearly parabolic trend. On the other hand, the tetragonal shear elastic constant C‧ decreases as x increases and correlates reasonably well with the structural energy difference between fcc and bcc structures. Our results offer a consistent starting point for further theoretical and experimental studies of the elastic and micromechanical properties of Au-V and Au-Nb systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birmingham, D.; Kantowski, R.; Milton, K.A.

We use two methods of computing the unique logarithmically divergent part of the Casimir energy for massive scalar and spinor fields defined on even-dimensional Kaluza-Klein spaces of the form M/sup 4/ x S/sup N//sup 1/ x S/sup N//sup 2/ x xxx. Both methods (heat kernel and direct) give identical results. The first evaluates the required internal zeta function by identifying it in the asymptotic expansion of the trace of the heat kernel, and the second evaluates the zeta function directly using the Euler-Maclaurin sum formula. In Appendix C we tabulate these energies for all spaces of total internal dimension lessmore » than or equal to6. These methods are easily applied to vector and tensor fields needed in computing one-loop vacuum gravitational energies on these spaces. Stable solutions are given for internal structure S/sup 2/ x S/sup 2/.« less

Assessing the performance of dispersionless and dispersion-accounting methods: helium interaction with cluster models of the TiO2(110) surface.

PubMed

de Lara-Castells, María Pilar; Stoll, Hermann; Mitrushchenkov, Alexander O

2014-08-21

As a prototypical dispersion-dominated physisorption problem, we analyze here the performance of dispersionless and dispersion-accounting methodologies on the helium interaction with cluster models of the TiO2(110) surface. A special focus has been given to the dispersionless density functional dlDF and the dlDF+Das construction for the total interaction energy (K. Pernal, R. Podeswa, K. Patkowski, and K. Szalewicz, Phys. Rev. Lett. 2009, 109, 263201), where Das is an effective interatomic pairwise functional form for the dispersion. Likewise, the performance of symmetry-adapted perturbation theory (SAPT) method is evaluated, where the interacting monomers are described by density functional theory (DFT) with the dlDF, PBE, and PBE0 functionals. Our benchmarks include CCSD(T)-F12b calculations and comparative analysis on the nuclear bound states supported by the He-cluster potentials. Moreover, intra- and intermonomer correlation contributions to the physisorption interaction are analyzed through the method of increments (H. Stoll, J. Chem. Phys. 1992, 97, 8449) at the CCSD(T) level of theory. This method is further applied in conjunction with a partitioning of the Hartree-Fock interaction energy to estimate individual interaction energy components, comparing them with those obtained using the different SAPT(DFT) approaches. The cluster size evolution of dispersionless and dispersion-accounting energy components is then discussed, revealing the reduced role of the dispersionless interaction and intramonomer correlation when the extended nature of the surface is better accounted for. On the contrary, both post-Hartree-Fock and SAPT(DFT) results clearly demonstrate the high-transferability character of the effective pairwise dispersion interaction whatever the cluster model is. Our contribution also illustrates how the method of increments can be used as a valuable tool not only to achieve the accuracy of CCSD(T) calculations using large cluster models but also to evaluate the performance of SAPT(DFT) methods for the physically well-defined contributions to the total interaction energy. Overall, our work indicates the excellent performance of a dlDF+Das approach in which the parameters are optimized using the smallest cluster model of the target surface to treat van der Waals adsorbate-surface interactions.

The rigid bi-functional sail, new concept concerning the reduction of the drag of ships

NASA Astrophysics Data System (ADS)

Țicu, I.; Popa, I.; Ristea, M.

2015-11-01

The policy of the European Union in the energy field, for the period to follow until 2020, is based on three fundamental objectives: sustainability, competitiveness and safety in energy supply. The “Energy - Climate Changes” program sets out a number of objectives for the EU for the year 2020, known as the “20-20-20 objectives”, namely: the reduction of greenhouse gas emissions by at least 20% from the level of those of 1990, a 20% increase in the share of renewable energy sources out of the total energy consumption as well as a target of 10% biofuels in the transports energy consumption. In this context, in order to produce or save a part of the propulsive power produced by the main propulsion machinery, by burning fossil fuels, we suggest the equipping of vessels designed for maritime transport with a bi-functional rigid sail. We consider that this device may have both the role of trapping wind energy and the role of acting as a deflector for reducing the resistance of the vessel's proceeding through the water by conveniently using the bow air current, as a result of the vessel's heading through the water with significant advantage in reducing the energy consumption for propulsion insurance.

Cyanidin-3-glucoside increases whole body energy metabolism by upregulating brown adipose tissue mitochondrial function.

PubMed

You, Yilin; Yuan, Xiaoxue; Liu, Xiaomeng; Liang, Chen; Meng, Minghui; Huang, Yuanyuan; Han, Xue; Guo, Jielong; Guo, Yu; Ren, Chenglong; Zhang, Qianwen; Sun, Xiangyu; Ma, Tingting; Liu, Guojie; Jin, Wanzhu; Huang, Weidong; Zhan, Jicheng

2017-11-01

Obesity develops when energy intake exceeds energy expenditure. Promoting brown adipose tissue (BAT) formation and function increases energy expenditure and may protect against obesity. Cyanidin-3-glucoside (C3G) is an anthocyanin compound that occurs naturally in many fruits and vegetables. In this study, we investigated the effect and mechanism of C3G on the prevention of obesity. Db/db mice received C3G dissolved in drinking water for 16 wk; drinking water served as the vehicle treatment. The total body weight, energy intake, metabolic rate, and physical activity were measured. The lipid droplets, gene expression and protein expression were evaluated by histochemical staining, real-time PCR, and western blots. We found that C3G increased energy expenditure, limited weight gain, maintained glucose homeostasis, reversed hepatic steatosis, improved cold tolerance, and enhanced BAT activity in obese db/db mice. C3G also induces brown-like adipocytes (beige) formation in subcutaneous white adipose tissue (sWAT) of db/db mice model. We also found that C3G potently regulates the transcription of uncoupling protein 1 (UCP1) both in BAT and sWAT through increasing mitochondrial number and function. Our results suggest that C3G plays a role in regulating systemic energy balance, which may have potential therapeutic implications for the prevention and control of obesity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Does extracorporeal shock wave lithotripsy cause hearing impairment in children?

PubMed

Tuncer, Murat; Sahin, Cahit; Yazici, Ozgur; Kafkasli, Alper; Turk, Akif; Erdogan, Banu A; Faydaci, Gokhan; Sarica, Kemal

2015-03-01

We evaluated the possible effects of noise created by high energy shock waves on the hearing function of children treated with extracorporeal shock wave lithotripsy. A total of 65 children with normal hearing function were included in the study. Patients were divided into 3 groups, ie those becoming stone-free after 1 session of shock wave lithotripsy (group 1, 22 children), those requiring 3 sessions to achieve stone-free status (group 2, 21) and healthy children/controls (group 3, 22). Extracorporeal shock wave lithotripsy was applied with patients in the supine position with a 90-minute frequency and a total of 2,000 shock waves in each session (Compact Sigma, Dornier MedTech, Wessling, Germany). Second energy level was used with a maximum energy value of 58 joules per session in all patients. Hearing function and possible cochlear impairment were evaluated by transient evoked otoacoustic emissions test at 1.0, 1.4, 2.0, 2.8 and 4.0 kHz frequencies before the procedure, 2 hours later, and 1 month after completion of the first shock wave lithotripsy session in groups 1 and 2. In controls the same evaluation procedures were performed at the beginning of the study and 7 weeks later. Regarding transient evoked otoacoustic emissions data, in groups 1 and 2 there was no significant alteration in values obtained after shock wave lithotripsy compared to values obtained at the beginning of the study, similar to controls. A well planned shock wave lithotripsy procedure is a safe and effective treatment in children with urinary stones and causes no detectable harmful effect on hearing function. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Multiconfiguration Pair-Density Functional Theory: A New Way To Treat Strongly Correlated Systems.

PubMed

Gagliardi, Laura; Truhlar, Donald G; Li Manni, Giovanni; Carlson, Rebecca K; Hoyer, Chad E; Bao, Junwei Lucas

2017-01-17

The electronic energy of a system provides the Born-Oppenheimer potential energy for internuclear motion and thus determines molecular structure and spectra, bond energies, conformational energies, reaction barrier heights, and vibrational frequencies. The development of more efficient and more accurate ways to calculate the electronic energy of systems with inherently multiconfigurational electronic structure is essential for many applications, including transition metal and actinide chemistry, systems with partially broken bonds, many transition states, and most electronically excited states. Inherently multiconfigurational systems are called strongly correlated systems or multireference systems, where the latter name refers to the need for using more than one ("multiple") configuration state function to provide a good zero-order reference wave function. This Account describes multiconfiguration pair-density functional theory (MC-PDFT), which was developed as a way to combine the advantages of wave function theory (WFT) and density functional theory (DFT) to provide a better treatment of strongly correlated systems. First we review background material: the widely used Kohn-Sham DFT (which uses only a single Slater determinant as reference wave function), multiconfiguration WFT methods that treat inherently multiconfigurational systems based on an active space, and previous attempts to combine multiconfiguration WFT with DFT. Then we review the formulation of MC-PDFT. It is a generalization of Kohn-Sham DFT in that the electron kinetic energy and classical electrostatic energy are calculated from a reference wave function, while the rest of the energy is obtained from a density functional. However, there are two main differences with respent to Kohn-Sham DFT: (i) The reference wave function is multiconfigurational rather than being a single Slater determinant. (ii) The density functional is a function of the total density and the on-top pair density rather than being a function of the spin-up and spin-down densities. In work carried out so far, the multiconfigurational wave function is a multiconfiguration self-consistent-field wave function. The new formulation has the advantage that the reference wave function has the correct spatial and spin symmetry and can describe bond dissociation (of both single and multiple bonds) and electronic excitations in a formally and physically correct way. We then review the formulation of density functionals in terms of the on-top pair density. Finally we review successful applications of the theory to bond energies and bond dissociation potential energy curves of main-group and transition metal bonds, to barrier heights (including pericyclic reactions), to proton affinities, to the hydrogen bond energy of water dimer, to ground- and excited-state charge transfer, to valence and Rydberg excitations of molecules, and to singlet-triplet splittings of radicals. We find that that MC-PDFT can give accurate results not only with complete-active-space multiconfiguration wave functions but also with generalized-active-space multiconfiguration wave functions, which are practical for larger numbers of active electrons and active orbitals than are complete-active-space wave functions. The separated-pair approximation, which is a special case of generalized active space self-consistent-field theory, is especially promising. MC-PDFT, because it requires much less computer time and storage than pure WFT methods, has the potential to open larger and more complex strongly correlated systems to accurate simulation.

Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans.

PubMed

Pontzer, Herman; Durazo-Arvizu, Ramon; Dugas, Lara R; Plange-Rhule, Jacob; Bovet, Pascal; Forrester, Terrence E; Lambert, Estelle V; Cooper, Richard S; Schoeller, Dale A; Luke, Amy

2016-02-08

Current obesity prevention strategies recommend increasing daily physical activity, assuming that increased activity will lead to corresponding increases in total energy expenditure and prevent or reverse energy imbalance and weight gain [1-3]. Such Additive total energy expenditure models are supported by exercise intervention and accelerometry studies reporting positive correlations between physical activity and total energy expenditure [4] but are challenged by ecological studies in humans and other species showing that more active populations do not have higher total energy expenditure [5-8]. Here we tested a Constrained total energy expenditure model, in which total energy expenditure increases with physical activity at low activity levels but plateaus at higher activity levels as the body adapts to maintain total energy expenditure within a narrow range. We compared total energy expenditure, measured using doubly labeled water, against physical activity, measured using accelerometry, for a large (n = 332) sample of adults living in five populations [9]. After adjusting for body size and composition, total energy expenditure was positively correlated with physical activity, but the relationship was markedly stronger over the lower range of physical activity. For subjects in the upper range of physical activity, total energy expenditure plateaued, supporting a Constrained total energy expenditure model. Body fat percentage and activity intensity appear to modulate the metabolic response to physical activity. Models of energy balance employed in public health [1-3] should be revised to better reflect the constrained nature of total energy expenditure and the complex effects of physical activity on metabolic physiology. Copyright © 2016 Elsevier Ltd. All rights reserved.

An extended hybrid density functional (X3LYP) with improved descriptions of nonbond interactions and thermodynamic properties of molecular systems

NASA Astrophysics Data System (ADS)

Xu, Xin; Zhang, Qingsong; Muller, Richard P.; Goddard, William A.

2005-01-01

We derive here the form for the exact exchange energy density for a density that decays with Gaussian-type behavior at long range. This functional is intermediate between the B88 and the PW91 exchange functionals. Using this modified functional to match the form expected for Gaussian densities, we propose the X3LYP extended functional. We find that X3LYP significantly outperforms Becke three parameter Lee-Yang-Parr (B3LYP) for describing van der Waals and hydrogen bond interactions, while performing slightly better than B3LYP for predicting heats of formation, ionization potentials, electron affinities, proton affinities, and total atomic energies as validated with the extended G2 set of atoms and molecules. Thus X3LYP greatly enlarges the field of applications for density functional theory. In particular the success of X3LYP in describing the water dimer (with Re and De within the error bars of the most accurate determinations) makes it an excellent candidate for predicting accurate ligand-protein and ligand-DNA interactions.

Electronic and thermal properties of germanene and stanene by first-principles calculations

NASA Astrophysics Data System (ADS)

Jomehpour Zaveh, S.; Roknabadi, M. R.; Morshedloo, T.; Modarresi, M.

2016-03-01

The electronic, vibrational and thermal properties of germanene and stanene have been investigated based on density functional theory (DFT) and density functional perturbation theory (DFPT). The electronic band structure, total and partial density of states and phonon dispersion spectrum and states are analyzed. The phonon spectrum is positive for all modes in the first Brillouin zone and there is a phonon energy band gap between acoustic and optical modes which is around 50 cm-1 for both structure. The constant-volume specific heats of two structures are calculated by using phonon spectrum and density of states. The spin-orbit coupling (SOC) opens a direct energy band gap at the Dirac point, softens phonon spectrum and decreases phonon group velocity of ZA mode.

DFTB Parameters for the Periodic Table, Part 2: Energies and Energy Gradients from Hydrogen to Calcium.

PubMed

Oliveira, Augusto F; Philipsen, Pier; Heine, Thomas

2015-11-10

In the first part of this series, we presented a parametrization strategy to obtain high-quality electronic band structures on the basis of density-functional-based tight-binding (DFTB) calculations and published a parameter set called QUASINANO2013.1. Here, we extend our parametrization effort to include the remaining terms that are needed to compute the total energy and its gradient, commonly referred to as repulsive potential. Instead of parametrizing these terms as a two-body potential, we calculate them explicitly from the DFTB analogues of the Kohn-Sham total energy expression. This strategy requires only two further numerical parameters per element. Thus, the atomic configuration and four real numbers per element are sufficient to define the DFTB model at this level of parametrization. The QUASINANO2015 parameter set allows the calculation of energy, structure, and electronic structure of all systems composed of elements ranging from H to Ca. Extensive benchmarks show that the overall accuracy of QUASINANO2015 is comparable to that of well-established methods, including PM7 and hand-tuned DFTB parameter sets, while coverage of a much larger range of chemical systems is available.

Cloud-generated radiative heating and its generation of available potential energy

NASA Technical Reports Server (NTRS)

Stuhlmann, R.; Smith, G. L.

1989-01-01

The generation of zonal available potential energy (APE) by cloud radiative heating is discussed. The APE concept was mathematically formulated by Lorenz (1955) as a measure of the maximum amount of total potential energy that is available for conversion by adiabatic processes to kinetic energy. The rate of change of APE is the rate of the generation of APE minus the rate of conversion between potential and kinetic energy. By radiative transfer calculations, a mean cloud-generated radiative heating for a well defined set of cloud classes is derived as a function of cloud optical thickness. The formulation is suitable for using a general cloud parameter data set and has the advantage of taking into account nonlinearities between the microphysical and macrophysical cloud properties and the related radiation field.

Why do Electrons with "Anomalous Energies" appear in High-Pressure Gas Discharges?

NASA Astrophysics Data System (ADS)

Kozyrev, Andrey; Kozhevnikov, Vasily; Semeniuk, Natalia

2018-01-01

Experimental studies connected with runaway electron beams generation convincingly shows the existence of electrons with energies above the maximum voltage applied to the discharge gap. Such electrons are also known as electrons with "anomalous energies". We explain the presence of runaway electrons having so-called "anomalous energies" according to physical kinetics principles, namely, we describe the total ensemble of electrons with the distribution function. Its evolution obeys Boltzmann kinetic equation. The dynamics of self-consistent electromagnetic field is taken into the account by adding complete Maxwell's equation set to the resulting system of equations. The electrodynamic mechanism of the interaction of electrons with a travelling-wave electric field is analyzed in details. It is responsible for the appearance of electrons with high energies in real discharges.

High quality Gaussian basis sets for fourth-row atoms

NASA Technical Reports Server (NTRS)

Partridge, Harry; Faegri, Knut, Jr.

1992-01-01

Energy optimized Gaussian basis sets of triple-zeta quality for the atoms Rb-Xe have been derived. Two series of basis sets are developed: (24s 16p 10d) and (26s 16p 10d) sets which were expanded to 13d and 19p functions as the 4d and 5p shells become occupied. For the atoms lighter than Cd, the (24s 16p 10d) sets with triple-zeta valence distributions are higher in energy than the corresponding double-zeta distribution. To ensure a triple-zeta distribution and a global energy minimum, the (26s 16p 10d) sets were derived. Total atomic energies from the largest basis sets are between 198 and 284 (mu)E(sub H) above the numerical Hartree-Fock energies.

Rechargeable Lithium-Ion Based Batteries and Thermal Management for Airborne High Energy Electric Lasers (Preprint)

DTIC Science & Technology

2006-08-01

applications have been substantial. Rechargeable high rate lithium - ion batteries are now exceeding 6 kW/kg for short discharge times 15 seconds...rechargeable lithium - ion batteries as a function of onboard power, electric laser power level, laser duty cycle, and total mission time is presented. A number

Oxygen disorder, a way to accommodate large epitaxial strains in oxides

DOE PAGES

Zhang, Yu Yang; Mishra, Rohan; Pennycook, Timothy J.; ...

2015-09-22

Density-functional calculations (total-energy comparisons) and checks for negative-frequency phonon modes are employed as a stability indicator to show that, in rutile- and fluorite-structure oxides, e.g., zirconia strained by a strontium titanate substrate, oxygen-sublattice disorder can be the energetically preferred way to accommodate strain.

Optimization of intermittent microwave–convective drying using response surface methodology

PubMed Central

Aghilinategh, Nahid; Rafiee, Shahin; Hosseinpur, Soleiman; Omid, Mahmoud; Mohtasebi, Seyed Saeid

2015-01-01

In this study, response surface methodology was used for optimization of intermittent microwave–convective air drying (IMWC) parameters with employing desirability function. Optimization factors were air temperature (40–80°C), air velocity (1–2 m/sec), pulse ratio) PR ((2–6), and microwave power (200–600 W) while responses were rehydration ratio, bulk density, total phenol content (TPC), color change, and energy consumption. Minimum color change, bulk density, energy consumption, maximum rehydration ratio, and TPC were assumed as criteria for optimizing drying conditions of apple slices in IMWC. The optimum values of process variables were 1.78 m/sec air velocity, 40°C air temperature, PR 4.48, and 600 W microwave power that characterized by maximum desirability function (0.792) using Design expert 8.0. The air temperature and microwave power had significant effect on total responses, but the role of air velocity can be ignored. Generally, the results indicated that it was possible to obtain a higher desirability value if the microwave power and temperature, respectively, increase and decrease. PMID:26286706

Electromagnetic pulses, localized and causal

NASA Astrophysics Data System (ADS)

Lekner, John

2018-01-01

We show that pulse solutions of the wave equation can be expressed as time Fourier superpositions of scalar monochromatic beam wave functions (solutions of the Helmholtz equation). This formulation is shown to be equivalent to Bateman's integral expression for solutions of the wave equation, for axially symmetric solutions. A closed-form one-parameter solution of the wave equation, containing no backward-propagating parts, is constructed from a beam which is the tight-focus limit of two families of beams. Application is made to transverse electric and transverse magnetic pulses, with evaluation of the energy, momentum and angular momentum for a pulse based on the general localized and causal form. Such pulses can be represented as superpositions of photons. Explicit total energy and total momentum values are given for the one-parameter closed-form pulse.

The role of confined collagen geometry in decreasing nucleation energy barriers to intrafibrillar mineralization.

PubMed

Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros; Jun, Young-Shin

2018-03-06

Mineralization of collagen is critical for the mechanical functions of bones and teeth. Calcium phosphate nucleation in collagenous structures follows distinctly different patterns in highly confined gap regions (nanoscale confinement) than in less confined extrafibrillar spaces (microscale confinement). Although the mechanism(s) driving these differences are still largely unknown, differences in the free energy for nucleation may explain these two mineralization behaviors. Here, we report on experimentally obtained nucleation energy barriers to intra- and extrafibrillar mineralization, using in situ X-ray scattering observations and classical nucleation theory. Polyaspartic acid, an extrafibrillar nucleation inhibitor, increases interfacial energies between nuclei and mineralization fluids. In contrast, the confined gap spaces inside collagen fibrils lower the energy barrier by reducing the reactive surface area of nuclei, decreasing the surface energy penalty. The confined gap geometry, therefore, guides the two-dimensional morphology and structure of bioapatite and changes the nucleation pathway by reducing the total energy barrier.

Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

DOE PAGES

Shi, Chenyang; Teerakapibal, Rattavut; Yu, Lian; ...

2017-07-10

Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accurate in situmore » structural studies for a wide range of materials.« less

Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Chenyang; Teerakapibal, Rattavut; Yu, Lian

2017-07-10

Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accuratein situstructuralmore » studies for a wide range of materials.« less

The Kinetics of Ouabain Inhibition and the Partition of Rubidium Influx in Human Red Blood Cells

PubMed Central

Beauge, L. A.; Adragna, Norma

1971-01-01

In the development of ouabain inhibition of rubidium influx in human red blood cells a time lag can be detected which is a function of at least three variables: the concentrations of external sodium, rubidium, and ouabain. The inhibition is antagonized by rubidium and favored by sodium. Similar considerations could be applied to the binding of ouabain to membrane sites. The total influx of rubidium as a function of external rubidium concentration can be separated into two components: (a) a linear uptake not affected by external sodium or ouabain and not requiring an energy supply, and (b) a saturable component. The latter component, on the basis of the different effects of the aforementioned factors, can be divided into three fractions. The first is ouabain-sensitive, inhibited by external sodium at low rubidium, and requires an energy supply; this represents about 70–80% of the total uptake and is related to the active sodium extrusion mechanism. The second is ouabain-insensitive, activated by external sodium over the entire range of rubidium concentrations studied, and dependent on internal ATP; this represents about 15% of the total influx; it could be coupled to an active sodium extrusion or belong to a rubidium-potassium exchange. The third, which can be called residual influx, is ouabain-insensitive, unaffected by external sodium, and independent of internal ATP; this represents about 10–20% of the total influx. PMID:5553102

Stochastic Optimally Tuned Range-Separated Hybrid Density Functional Theory.

PubMed

Neuhauser, Daniel; Rabani, Eran; Cytter, Yael; Baer, Roi

2016-05-19

We develop a stochastic formulation of the optimally tuned range-separated hybrid density functional theory that enables significant reduction of the computational effort and scaling of the nonlocal exchange operator at the price of introducing a controllable statistical error. Our method is based on stochastic representations of the Coulomb convolution integral and of the generalized Kohn-Sham density matrix. The computational cost of the approach is similar to that of usual Kohn-Sham density functional theory, yet it provides a much more accurate description of the quasiparticle energies for the frontier orbitals. This is illustrated for a series of silicon nanocrystals up to sizes exceeding 3000 electrons. Comparison with the stochastic GW many-body perturbation technique indicates excellent agreement for the fundamental band gap energies, good agreement for the band edge quasiparticle excitations, and very low statistical errors in the total energy for large systems. The present approach has a major advantage over one-shot GW by providing a self-consistent Hamiltonian that is central for additional postprocessing, for example, in the stochastic Bethe-Salpeter approach.

Multifunctional Woven Structure Operating as Triboelectric Energy Harvester, Capacitive Tactile Sensor Array, and Piezoresistive Strain Sensor Array

PubMed Central

Kim, Kihong; Song, Giyoung; Park, Cheolmin; Yun, Kwang-Seok

2017-01-01

This paper presents a power-generating sensor array in a flexible and stretchable form. The proposed device is composed of resistive strain sensors, capacitive tactile sensors, and a triboelectric energy harvester in a single platform. The device is implemented in a woven textile structure by using proposed functional threads. A single functional thread is composed of a flexible hollow tube coated with silver nanowires on the outer surface and a conductive silver thread inside the tube. The total size of the device is 60 × 60 mm2 having a 5 × 5 array of sensor cell. The touch force in the vertical direction can be sensed by measuring the capacitance between the warp and weft functional threads. In addition, because silver nanowire layers provide piezoresistivity, the strain applied in the lateral direction can be detected by measuring the resistance of each thread. Last, with regard to the energy harvester, the maximum power and power density were measured as 201 μW and 0.48 W/m2, respectively, when the device was pushed in the vertical direction. PMID:29120363

CuPc/Au(1 1 0): Determination of the azimuthal alignment by a combination of angle-resolved photoemission and density functional theory

PubMed Central

Lüftner, Daniel; Milko, Matus; Huppmann, Sophia; Scholz, Markus; Ngyuen, Nam; Wießner, Michael; Schöll, Achim; Reinert, Friedrich; Puschnig, Peter

2014-01-01

Here we report on a combined experimental and theoretical study on the structural and electronic properties of a monolayer of Copper-Phthalocyanine (CuPc) on the Au(1 1 0) surface. Low-energy electron diffraction reveals a commensurate overlayer unit cell containing one adsorbate species. The azimuthal alignment of the CuPc molecule is revealed by comparing experimental constant binding energy (kxky)-maps using angle-resolved photoelectron spectroscopy with theoretical momentum maps of the free molecule's highest occupied molecular orbital (HOMO). This structural information is confirmed by total energy calculations within the framework of van-der-Waals corrected density functional theory. The electronic structure is further analyzed by computing the molecule-projected density of states, using both a semi-local and a hybrid exchange-correlation functional. In agreement with experiment, the HOMO is located about 1.2 eV below the Fermi-level, while there is no significant charge transfer into the molecule and the CuPc LUMO remains unoccupied on the Au(1 1 0) surface. PMID:25284953

Kinetics evaluation and thermal decomposition characteristics of co-pyrolysis of municipal sewage sludge and hazelnut shell.

PubMed

Zhao, Bing; Xu, Xinyang; Li, Haibo; Chen, Xi; Zeng, Fanqiang

2018-01-01

Hazelnut shell, as novel biomass, has lower ash content and abundant hydrocarbon, which can be utilized resourcefully with municipal sewage sludge (MSS) by co-pyrolyisis to decrease total content of pollution. The co-pyrolysis of MSS and hazelnut shell blend was analyzed by a method of multi-heating rates and different blend ratios with TG-DTG-MS under N 2 atmosphere. The apparent activation energy of co-pyrolysis was calculated by three iso-conversional methods. Satava-Sestak method was used to determine mechanism function G(α) of co-pyrolysis, and Lorentzian function was used to simulate multi-peaks curves. The results showed there were four thermal decomposition stages, and the biomass were cracked and evolved at different temperature ranges. The apparent activation energy increased from 123.99 to 608.15kJ/mol. The reaction mechanism of co-pyrolysis is random nucleation and nuclei growth. The apparent activation energy and mechanism function afford a theoretical groundwork for co-pyrolysis technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

A minimal model for the structural energetics of VO2

NASA Astrophysics Data System (ADS)

Kim, Chanul; Marianetti, Chris; The Marianetti Group Team

Resolving the structural, magnetic, and electronic structure of VO2 from the first-principles of quantum mechanics is still a forefront problem despite decades of attention. Hybrid functionals have been shown to qualitatively ruin the structural energetics. While density functional theory (DFT) combined with cluster extensions of dynamical mean-field theory (DMFT) have demonstrated promising results in terms of the electronic properties, structural phase stability has not yet been addressed. In order to capture the basic physics of the structural transition, we propose a minimal model of VO2 based on the one dimensional Peierls-Hubbard model and parameterize this based on DFT calculations of VO2. The total energy versus dimerization in the minimal mode is then solved numerically exactly using density matrix renormalization group (DMRG) and compared to the Hartree-Fock solution. We demonstrate that the Hartree-Fock solution exhibits the same pathologies as DFT+U, and spin density functional theory for that matter, while the DMRG solution is consistent with experimental observation. Our results demonstrate the critical role of non-locality in the total energy, and this will need to be accounted for to obtain a complete description of VO2 from first-principles. The authors acknowledge support from FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

A Density Functional Study of Atomic Hydrogen and Oxygen Chemisorptions on the (0001) Surface of Double Hexagonal Close Packed Americium

NASA Astrophysics Data System (ADS)

Dholabhai, Pratik; Atta-Fynn, Raymond; Ray, Asok

2008-03-01

Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorptions on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals (FLAPW+lo) method. The three-fold hollow hcp site was found to be the most stable site for H adsorption, while the two-fold bridge adsorption site was found to be the most stable site for O adsorption. Chemisorption energies and adsorption geometries for different adsorption sites will be discussed. The change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the adatom will be discussed. The implications of chemisorption on Am 5f electron localization-delocalization will also be discussed.

Mass Yields and Average Total Kinetic Energy Release in Fission for 235U, 238U, and 239Pu

NASA Astrophysics Data System (ADS)

Duke, Dana

2015-10-01

Mass yield distributions and average total kinetic energy (TKE) in neutron induced fission of 235U, 238U, and 239Pu targets were measured with a gridded ionization chamber. Despite decades of fission research, our understanding of how fragment mass yields and TKE depend on incident neutron energy is limited, especially at higher energies (above 5-10 MeV). Improved accuracy in these quantities is important for nuclear technology as it enhances our simulation capabilities and increases the confidence in diagnostic tools. The data can also guide and validate theoretical fission models where the correlation between the fragment mass and TKE is of particular value for constraining models. The Los Alamos Neutron Science Center - Weapons Neutron Research (LANSCE - WNR) provides a neutron beam with energies from thermal to hundreds of MeV, well-suited for filling in the gaps in existing data and exploring fission behavior in the fast neutron region. The results of the studies on target nuclei 235U, 238U, and 239Pu will be presented with a focus on exploring data trends as a function of neutron energy from thermal through 30 MeV. Results indicate clear evidence of structure due to multi-chance fission in the TKE . LA-UR-15-24761.

Determination of wave-function functionals: The constrained-search variational method

NASA Astrophysics Data System (ADS)

Pan, Xiao-Yin; Sahni, Viraht; Massa, Lou

2005-09-01

In a recent paper [Phys. Rev. Lett. 93, 130401 (2004)], we proposed the idea of expanding the space of variations in variational calculations of the energy by considering the approximate wave function ψ to be a functional of functions χ , ψ=ψ[χ] , rather than a function. A constrained search is first performed over all functions χ such that the wave-function functional ψ[χ] satisfies a physical constraint or leads to the known value of an observable. A rigorous upper bound to the energy is then obtained via the variational principle. In this paper we generalize the constrained-search variational method, applicable to both ground and excited states, to the determination of arbitrary Hermitian single-particle operators as applied to two-electron atomic and ionic systems. We construct analytical three-parameter ground-state functionals for the H- ion and the He atom through the constraint of normalization. We present the results for the total energy E , the expectations of the single-particle operators W=∑irin , n=-2,-1,1,2 , W=∑iδ(ri) , and W=∑iδ(ri-r) , the structure of the nonlocal Coulomb hole charge ρc(rr') , and the expectations of the two particle operators u2,u,1/u,1/u2 , where u=∣ri-rj∣ . The results for all the expectation values are remarkably accurate when compared with the 1078-parameter wave function of Pekeris, and other wave functions that are not functionals. We conclude by describing our current work on how the constrained-search variational method in conjunction with quantal density-functional theory is being applied to the many-electron case.

Oxygenation-linked subunit interactions in human hemoglobin: analysis of linkage functions for constituent energy terms.

PubMed

Johnson, M L; Halvorson, H R; Ackers, G K

1976-11-30

Resolution of the linkage functions between oxygenation and subunit association-dissociation equilibria in human hemoglobin into the constituent microscopic terms has been explored by numerical simulation and least-squares analysis. The correlation properties between parameters has been studied using several choices of parameter sets in order to optimize resolution. It is found that, with currently available levels of experimental precision and ranges of variables, neither linkage function can provide sufficient resolution of all the desired energy terms. The most difficult quantities to resolve always include the dimer-tetramer association constant for unliganded hemoglobin and the oxygen binding constants to alphabeta dimers. A feasible experimental strategy for overcoming these difficulties lies in independent determination of the dimer-tetramer association constants for unliganded and fully oxygenated hemoglobin. These constants, in combination with the median lignad concentration, provide an estimate of the energy for total oxygenation of tetramers which is essentially independent of the other constituent energies. It is shown that if these separately determinable parameters are fixed, the remaining terms may be estimated to good accuracy using data which represents either linkage function. In general it is desirable to combine information from both types of experimental quantities. A previous paper (Mills, F.C., Johnson, M.L., and Ackers, G.K. (1976), Biochemestry, 15, the preceding paper in this issue) describes the experimental implementation of this strategy.

Two-photon double ionization of helium in the region of photon energies 42-50eV

NASA Astrophysics Data System (ADS)

Ivanov, I. A.; Kheifets, A. S.

2007-03-01

We report the total integrated cross section (TICS) of two-photon double ionization of helium in the photon energy range from 42to50eV . Our computational procedure relies on a numerical solution of the time-dependent Schrödinger equation on a square-integrable basis and subsequent projection of this solution on a set of final field-free states describing correlation in the two-electron continuum. Our results suggest that the TICS grows monotonically as a function of photon energy in the region of 42-50eV , possibly reaching a maximum in the vicinity of 50eV . We also present fully resolved triple-differential cross sections for selected photon energies.

Optimal guidance for the space shuttle transition

NASA Technical Reports Server (NTRS)

Stengel, R. F.

1972-01-01

A guidance method for the space shuttle's transition from hypersonic entry to subsonic cruising flight is presented. The method evolves from a numerical trajectory optimization technique in which kinetic energy and total energy (per unit weight) replace velocity and time in the dynamic equations. This allows the open end-time problem to be transformed to one of fixed terminal energy. In its ultimate form, E-Guidance obtains energy balance (including dynamic-pressure-rate damping) and path length control by angle-of-attack modulation and cross-range control by roll angle modulation. The guidance functions also form the basis for a pilot display of instantaneous maneuver limits and destination. Numerical results illustrate the E-Guidance concept and the optimal trajectories on which it is based.

An ab initio study on the four electronically lowest-lying states of CH 2 using the state-averaged complete active space second-order configuration interaction method

NASA Astrophysics Data System (ADS)

Yamaguchi, Yukio; Schaefer, Henry F., III

1997-12-01

Four electronically lowest-lying ( X˜ 3B 1, ã 1A 1, b˜ 1B 1, and c˜ 1A 1) states of CH 2 have been investigated systematically using ab initio electronic structure theory. Complete active space (CAS) self-consistent-field (SCF) second-order configuration interaction (SOCI) and state-averaged (SA) CASSCF-SOCI levels of theory have been employed. The CASSCF reference wave function was constructed by minimizing the total energy of a specified state, while the SACASSCF reference wave function was obtained by minimizing the equally weighted total energy of the four ( X˜ 3B 1, ã 1A 1, b˜ 1B 1, and c˜ 1A 1) states. The third excited state ( c˜ 1A 1 or 2 1A 1) is of particular theoretical interest because it is represented by the second root of CASSCF and SOCI Hamiltonian matrices. Theoretical treatments of states not the lowest of their symmetry require special attention due to their tendency of variational collapse to the lower-lying state(s). For these four lowest-lying states total energies and physical properties including dipole moments, harmonic vibrational frequencies, and associated infrared (IR) intensities were determined and compared with the results from the configuration interaction with single and double excitations (CISD) method and available experimental values. The CASSCF-SOCI method should provide the most reliable energetics and physical properties in the present study owing to its fully variational nature in the molecular orbital (MO) and CI spaces for a given state. It is demonstrated that the SACASSCF-SOCI wave functions produce results which are quite consistent with those from the CASSCF-SOCI method. Thus significantly increased application of the SACASSCF-SOCI method to the excited states of a wide variety of molecular systems is expected.

The evolution of nutritional status of geriatric patients without cachexia is associated with food intake in sub-acute care.

PubMed

St-Arnaud McKenzie, D; Kergoat, M-J; Dube, L; Ferland, G

2009-02-01

To determine if changes in patients' nutritional status during hospitalization are related to daily energy and protein intakes when cachectic/inflammatory conditions are controlled for. Prospective study. A total of 32 non-cachectic patients (21 women; 65-92 y). Nutritional status was evaluated at admission and discharge using the Protein-Energy Malnutrition Index which includes BMI, %IBW, TS, MAC, albumin, hemoglobin and lymphocyte count. Food intake was assessed 3 meals/day every other day for an average of 46.2 +/- 14.6 meals/participant. In all, 47% of the study sample was malnourished at admission. Nutritional status improved in 73% of patients who had been identified as malnourished and in 30 % of non-malnourished patients at admission. Total energy intake correlated with improvements in BMI, %IBW and total lymphocyte count (all p < 0.04). Improvement in PEMI score for the whole group was associated with functional status (p < 0.05). Controlling for this variable, energy (kj/kg body weight) and protein (g/kg body weight) intakes correlated positively with improvements in BMI, %IBW and MAC (Energy: partial r = 0.644, 0.624, 0.466 respectively; Protein: partial r = 0.582, 0.554, 0.433 respectively; all p < 0.05). Results from this study offer strong evidence that when cachectic/inflammatory conditions are controlled for, standard nutrition care is compatible with the maintenance or improvement of nutritional status during the hospital stay.

Low-energy particle experiments-electron analyzer (LEPe) onboard the Arase spacecraft

NASA Astrophysics Data System (ADS)

Kazama, Yoichi; Wang, Bo-Jhou; Wang, Shiang-Yu; Ho, Paul T. P.; Tam, Sunny W. Y.; Chang, Tzu-Fang; Chiang, Chih-Yu; Asamura, Kazushi

2017-12-01

In this report, we describe the low-energy electron instrument LEPe (low-energy particle experiments-electron analyzer) onboard the Arase (ERG) spacecraft. The instrument measures a three-dimensional distribution function of electrons with energies of ˜ 19 eV-19 keV. Electrons in this energy range dominate in the inner magnetosphere, and measurement of such electrons is important in terms of understanding the magnetospheric dynamics and wave-particle interaction. The instrument employs a toroidal tophat electrostatic energy analyzer with a passive 6-mm aluminum shield. To minimize background radiation effects, the analyzer has a background channel, which monitors counts produced by background radiation. Background counts are then subtracted from measured counts. Electronic components are radiation tolerant, and 5-mm-thick shielding of the electronics housing ensures that the total dose is less than 100 kRad for the one-year nominal mission lifetime. The first in-space measurement test was done on February 12, 2017, showing that the instrument functions well. On February 27, the first all-instrument run test was done, and the LEPe instrument measured an energy dispersion event probably related to a substorm injection occurring immediately before the instrument turn-on. These initial results indicate that the instrument works fine in space, and the measurement performance is good for science purposes.[Figure not available: see fulltext.

Manipulation of a Nuclear Spin by a Magnetic Domain Wall in a Quantum Hall Ferromagnet.

PubMed

Korkusinski, M; Hawrylak, P; Liu, H W; Hirayama, Y

2017-03-06

The manipulation of a nuclear spin by an electron spin requires the energy to flip the electron spin to be vanishingly small. This can be realized in a many electron system with degenerate ground states of opposite spin polarization in different Landau levels. We present here a microscopic theory of a domain wall between spin unpolarized and spin polarized quantum Hall ferromagnet states at filling factor two with the Zeeman energy comparable to the cyclotron energy. We determine the energies and many-body wave functions of the electronic quantum Hall droplet with up to N = 80 electrons as a function of the total spin, angular momentum, cyclotron and Zeeman energies from the spin singlet ν = 2 phase, through an intermediate polarization state exhibiting a domain wall to the fully spin-polarized phase involving the lowest and the second Landau levels. We demonstrate that the energy needed to flip one electron spin in a domain wall becomes comparable to the energy needed to flip the nuclear spin. The orthogonality of orbital electronic states is overcome by the many-electron character of the domain - the movement of the domain wall relative to the position of the nuclear spin enables the manipulation of the nuclear spin by electrical means.

Manipulation of a Nuclear Spin by a Magnetic Domain Wall in a Quantum Hall Ferromagnet

PubMed Central

Korkusinski, M.; Hawrylak, P.; Liu, H. W.; Hirayama, Y.

2017-01-01

The manipulation of a nuclear spin by an electron spin requires the energy to flip the electron spin to be vanishingly small. This can be realized in a many electron system with degenerate ground states of opposite spin polarization in different Landau levels. We present here a microscopic theory of a domain wall between spin unpolarized and spin polarized quantum Hall ferromagnet states at filling factor two with the Zeeman energy comparable to the cyclotron energy. We determine the energies and many-body wave functions of the electronic quantum Hall droplet with up to N = 80 electrons as a function of the total spin, angular momentum, cyclotron and Zeeman energies from the spin singlet ν = 2 phase, through an intermediate polarization state exhibiting a domain wall to the fully spin-polarized phase involving the lowest and the second Landau levels. We demonstrate that the energy needed to flip one electron spin in a domain wall becomes comparable to the energy needed to flip the nuclear spin. The orthogonality of orbital electronic states is overcome by the many-electron character of the domain - the movement of the domain wall relative to the position of the nuclear spin enables the manipulation of the nuclear spin by electrical means. PMID:28262758

Complex Correlation Calculation of e-H Total Cross Sections

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

2001-01-01

Calculation of e-H total and elastic partial wave cross sections is being carried out using the complex correlation variational T-matrix method. In this preliminary study, elastic partial wave phase shifts are calculated with the correlation functions which are confined to be real. In that case the method reduces to the conventional optical potential approach with projection operators. The number of terms in the Hylleraas-type wave function for the S phase shifts is 95 while for the S it is 56, except for k=0.8 where it is 84. Our results, which are rigorous lower bounds, are given. They are seen to be in general agreement with those of Schwartz, but they are of 0 greater accuracy and outside of his error limits for k=0.3 and 0.4 for S. The main aim of this approach' is the application to higher energy scattering. By virtue of the complex correlation functions, the T matrix is not unitary so that elastic and total scattering cross sections are independent of each other. Our results will be compared specifically with those of Bray and Stelbovics.

Complex Correlation Calculation of e(-) - H Total Cross Sections

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

2001-01-01

Calculation of e(-) - H total and elastic partial wave cross sections is being carried out using the complex correlation variational T-matrix method. In this preliminary study, elastic partial wave phase shifts are calculated with the correlation functions which are confined to be real. In that case the method reduces to the conventional optical potential approach with 2 projection operators. The number of terms in the Hylleraas-type wave function for the S-1 phase shifts is 95 while for the S-3 it is 56, except for k = 0.8 where it is 84. Our results, which are rigorous lower bounds, are seen to be in general agreement with those of Schwartz, but they are of greater accuracy and outside of his error limits for k = 0.3 and 0.4 for S-1. The main aim of this approach is the application to higher energy scattering. By virtue of the complex correlation functions, the T-matrix is not unitary so that elastic and total scattering cross sections are independent of each other. Our results will be compared specifically with those of Bray and Stelbovics.

Variational model for one-dimensional quantum magnets

NASA Astrophysics Data System (ADS)

Kudasov, Yu. B.; Kozabaranov, R. V.

2018-04-01

A new variational technique for investigation of the ground state and correlation functions in 1D quantum magnets is proposed. A spin Hamiltonian is reduced to a fermionic representation by the Jordan-Wigner transformation. The ground state is described by a new non-local trial wave function, and the total energy is calculated in an analytic form as a function of two variational parameters. This approach is demonstrated with an example of the XXZ-chain of spin-1/2 under a staggered magnetic field. Generalizations and applications of the variational technique for low-dimensional magnetic systems are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Soumya; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

Electron transfer and proton coupled electron transfer (PCET) reactions at electrochemical interfaces play an essential role in a broad range of energy conversion processes. The reorganization energy, which is a measure of the free energy change associated with solute and solvent rearrangements, is a key quantity for calculating rate constants for these reactions. We present a computational method for including the effects of the double layer and ionic environment of the diffuse layer in calculations of electrochemical solvent reorganization energies. This approach incorporates an accurate electronic charge distribution of the solute within a molecular-shaped cavity in conjunction with a dielectricmore » continuum treatment of the solvent, ions, and electrode using the integral equations formalism polarizable continuum model. The molecule-solvent boundary is treated explicitly, but the effects of the electrode-double layer and double layer-diffuse layer boundaries, as well as the effects of the ionic strength of the solvent, are included through an external Green’s function. The calculated total reorganization energies agree well with experimentally measured values for a series of electrochemical systems, and the effects of including both the double layer and ionic environment are found to be very small. This general approach was also extended to electrochemical PCET and produced total reorganization energies in close agreement with experimental values for two experimentally studied PCET systems. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less

Synoptic, Global Mhd Model For The Solar Corona

NASA Astrophysics Data System (ADS)

Cohen, Ofer; Sokolov, I. V.; Roussev, I. I.; Gombosi, T. I.

2007-05-01

The common techniques for mimic the solar corona heating and the solar wind acceleration in global MHD models are as follow. 1) Additional terms in the momentum and energy equations derived from the WKB approximation for the Alfv’en wave turbulence; 2) some empirical heat source in the energy equation; 3) a non-uniform distribution of the polytropic index, γ, used in the energy equation. In our model, we choose the latter approach. However, in order to get a more realistic distribution of γ, we use the empirical Wang-Sheeley-Arge (WSA) model to constrain the MHD solution. The WSA model provides the distribution of the asymptotic solar wind speed from the potential field approximation; therefore it also provides the distribution of the kinetic energy. Assuming that far from the Sun the total energy is dominated by the energy of the bulk motion and assuming the conservation of the Bernoulli integral, we can trace the total energy along a magnetic field line to the solar surface. On the surface the gravity is known and the kinetic energy is negligible. Therefore, we can get the surface distribution of γ as a function of the final speed originating from this point. By interpolation γ to spherically uniform value on the source surface, we use this spatial distribution of γ in the energy equation to obtain a self-consistent, steady state MHD solution for the solar corona. We present the model result for different Carrington Rotations.

The eMouveRecherche application competes with research devices to evaluate energy expenditure, physical activity and still time in free-living conditions.

PubMed

Guidoux, Romain; Duclos, Martine; Fleury, Gérard; Lacomme, Philippe; Lamaudière, Nicolas; Saboul, Damien; Ren, Libo; Rousset, Sylvie

2017-05-01

The proliferation of smartphones is creating new opportunities to monitor and interact with human subjects in free-living conditions since smartphones are familiar to large segments of the population and facilitate data collection, transmission and analysis. From accelerometry data collected by smartphones, the present work aims to estimate time spent in different activity categories and the energy expenditure in free-living conditions. Our research encompasses the definition of an energy-saving function (Pred EE ) considering four physical categories of activities (still, light, moderate and vigorous), their duration and metabolic cost (MET). To create an efficient discrimination function, the method consists of classifying accelerometry-transformed signals into categories and of associating each category with corresponding Metabolic Equivalent Tasks. The performance of the Pred EE function was compared with two previously published functions (f(η,d)aedes,f(η,d)nrjsi), and with two dedicated sensors (Armband® and Actiheart®) in free-living conditions over a 12-h monitoring period using 30 volunteers. Compared to the two previous functions, Pred EE was the only one able to provide estimations of time spent in each activity category. In relative value, all the activity categories were evaluated similarly to those given by Armband®. Compared to Actiheart®, the function underestimated still activities by 10.1% and overestimated light- and moderate-intensity activities by 7.9% and 4.2%, respectively. The total energy expenditure error produced by Pred EE compared to Armband® was lower than those given by the two previous functions (5.7% vs. 14.1% and 17.0%). Pred EE provides the user with an accurate physical activity feedback which should help self-monitoring in free-living conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

Ab initio molecular simulations with numeric atom-centered orbitals

NASA Astrophysics Data System (ADS)

Blum, Volker; Gehrke, Ralf; Hanke, Felix; Havu, Paula; Havu, Ville; Ren, Xinguo; Reuter, Karsten; Scheffler, Matthias

2009-11-01

We describe a complete set of algorithms for ab initio molecular simulations based on numerically tabulated atom-centered orbitals (NAOs) to capture a wide range of molecular and materials properties from quantum-mechanical first principles. The full algorithmic framework described here is embodied in the Fritz Haber Institute "ab initio molecular simulations" (FHI-aims) computer program package. Its comprehensive description should be relevant to any other first-principles implementation based on NAOs. The focus here is on density-functional theory (DFT) in the local and semilocal (generalized gradient) approximations, but an extension to hybrid functionals, Hartree-Fock theory, and MP2/GW electron self-energies for total energies and excited states is possible within the same underlying algorithms. An all-electron/full-potential treatment that is both computationally efficient and accurate is achieved for periodic and cluster geometries on equal footing, including relaxation and ab initio molecular dynamics. We demonstrate the construction of transferable, hierarchical basis sets, allowing the calculation to range from qualitative tight-binding like accuracy to meV-level total energy convergence with the basis set. Since all basis functions are strictly localized, the otherwise computationally dominant grid-based operations scale as O(N) with system size N. Together with a scalar-relativistic treatment, the basis sets provide access to all elements from light to heavy. Both low-communication parallelization of all real-space grid based algorithms and a ScaLapack-based, customized handling of the linear algebra for all matrix operations are possible, guaranteeing efficient scaling (CPU time and memory) up to massively parallel computer systems with thousands of CPUs.

AB INITIO STUDY OF STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF MgxCd1-xX (X = S, Se, Te) ALLOYS

NASA Astrophysics Data System (ADS)

Noor, N. A.; Shaukat, A.

2012-12-01

This study describes structural, electronic and optical properties of MgxCd1-xX (X = S, Se, Te) alloys in the complete range 0≤x ≤1 of composition x in the zinc-blende (ZB) phase with the help of full-potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method within density functional theory (DFT). In order to calculate total energy, generalized gradient approximation (Wu-Cohen GGA) has been applied, which is based on optimization energy. For electronic structure calculations, the corresponding potential is being optimized by Engel-Vosko GGA formalism. Our calculations reveal the nonlinear variation of lattice constant and bulk modulus with different concentration for the end binary and their ternary alloys, which slightly deviates from Vegard's law. The calculated band structures show a direct band gap for all three alloys with increasing order in the complete range of the compositional parameter x. In addition, we have discussed the disorder parameter (gap bowing) and concluded that the total band gap bowing is substantially influenced by the chemical (electronegativity) contribution. The calculated density of states (DOS) of these alloys is discussed in terms of contribution from various s-, p- and d-states of the constituent atoms and charge density distributions plots are analyzed. Optical properties have been presented in the form of the complex dielectric function ɛ(ω), refractive index n(ω) and extinction coefficient k(ω) as function of the incident photon energy, and the results have been compared with existing experimental data and other theoretical calculations.

Conformational study of glyoxal bis(amidinohydrazone) by ab initio methods

NASA Astrophysics Data System (ADS)

Mannfors, B.; Koskinen, J. T.; Pietilä, L.-O.

1997-08-01

We report the first ab initio molecular orbital study on the ground state of the endiamine tautomer of glyoxal bis(amidinohydrazone) (or glyoxal bis(guanylhydrazone), GBG) free base. The calculations were performed at the following levels of theory: Hartree-Fock, second-order Møller-Plesset perturbation theory and density functional theory (B-LYP and B3-LYP) as implemented in the Gaussian 94 software. The standard basis set 6-31G(d) was found to be sufficient. The default fine grid of Gaussian 94 was used in the density functional calculations. Molecular properties, such as optimized structures, total energies and the electrostatic potential derived (CHELPG) atomic charges, were studied as functions of C-C and N-N conformations. The lowest energy conformation was found to be all- trans, in agreement with the experimental solid-state structure. The second conformer with respect to rotation around the central C-C bond was found to be the cis conformer with an MP2//HF energy of 4.67 kcal mol -1. For rotation around the N-N bond the energy increased monotonically from the trans conformation to the cis conformation, the cis energy being very high, 22.01 kcal mol -1 (MP2//HF). The atomic charges were shown to be conformation dependent, and the bond charge increments and especially the conformational changes of the bond charge increments were found to be easily transferable between structurally related systems.

Spin excitations in the deformed nuclei 154Sm, 158Gd and 168Er

NASA Astrophysics Data System (ADS)

Frekers, D.; Wörtche, H. J.; Richter, A.; Abegg, R.; Azuma, R. E.; Celler, A.; Chan, C.; Drake, T. E.; Helmer, R.; Jackson, K. P.; King, J. D.; Miller, C. A.; Schubank, R.; Vetterli, M. C.; Yen, S.

1990-07-01

An intermediate energy proton scattering experiment has been performed to probe spin excitation in the deformed rare earth nuclei 154Sm, 158Gd and 168Er for energies up to 12 MeV. A concentration of spin M1 strength is observed between 6 and 10MeV with a total strength of about 11 μN2 independent of the nucleus. The strength function shows two distinct structures separated by about 2.5 MeV and each having a width of about 2 MeV.

Electroform replication used for multiple X-ray mirror production

NASA Technical Reports Server (NTRS)

Kowalski, M. P.; Ulmer, M. P.; Purcell, W. R., Jr.; Loughlin, J. E. A.

1984-01-01

The electroforming technique for producing X-ray mirrors is described, and results of X-ray tests performed on copies made from a simple conical mandrel are reported. The design of the mandrel is depicted and the total reflectivity as well as the full-wave half modulation resolution are shown as a function of energy. The reported work has improved on previous studies by providing smaller grazing angles, making measurements at higher energies, producing about four times as many replicas from one mandrel, and obtaining better angular resolution.

Effect of the addition of β-mannanase on the performance, metabolizable energy, amino acid digestibility coefficients, and immune functions of broilers fed different nutritional levels

PubMed Central

Ferreira, H. C.; Hannas, M. I.; Albino, L. F. T.; Rostagno, H. S.; Neme, R.; Faria, B. D.; Xavier, M. L.; Rennó, L. N.

2016-01-01

Three experiments were conducted to evaluate the effect of β-mannanase (BM) supplementation on the performance, metabolizable energy, amino acid digestibility, and immune function of broilers. A total of 1,600 broilers were randomly distributed in a 4 × 2 factorial arrangement (4 nutritional levels × 0 or 500 g/ton BM), with 10 replicates and 20 broilers per pen. The same design was used in the energy and digestibility experiments with 8 and 6 replicates, respectively, and 6 broilers per pen. The nutritional levels (NL) were formulated to meet the nutritional requirements of broilers (NL1); reductions of 100 kcal metabolizable energy (NL2); 3% of the total amino acids (NL3); and 100 kcal metabolizable energy and 3% total amino acids (NL4) from NL1. The serum immunoglobulin (Ig) concentration was determined in two broilers per pen, and these broilers were slaughtered to determine the relative weight of spleen, thymus, and bursa of Fabricius. Throughout the experiment, the lower nutritional levels reduced (P < 0.05) body weight gain (BWG) and increased (P < 0.05) feed conversion (FCR) for the NL4 treatment. The BM increased (P < 0.05) the BWG values and improved (P < 0.05) the FCR of the broilers. The apparent metabolizable energy corrected for nitrogen balance (AMEn) values were reduced (P < 0.05) for NL2 and NL3. The BM increased (P < 0.05) the AMEn values and reduced (P < 0.05) the excreted nitrogen. NL3 and NL4 reduced (P < 0.05) the true ileal digestibility coefficients (TIDc) of the amino acids cystine and glycine, and BM increased (P < 0.05) the TIDc for all amino acids. The addition of BM reduced (P < 0.05) the relative weights of the spleen and bursa. NL2 increased (P < 0.05) the Ig values, whereas BM reduced (P < 0.05) the serum IgA, IgG, and IgM values of the broilers. This study indicates that using suboptimal nutrient levels leads to losses in production parameters, whereas BM-supplemented diets were effective in improving performance, energy values, and TIDc levels of amino acids and immune response of broilers. PMID:27038422

Effects of Corticosterone and Dietary Energy on Immune Function of Broiler Chickens

PubMed Central

Sheikhahmadi, Ardashir; Wang, Yufeng; Li, Congcong; Jiao, Hongchao; Lin, Hai; Song, Zhigang

2015-01-01

An experiment was conducted to investigate the effects of dietary energy level on the performance and immune function of stressed broiler chickens (Gallus gallus domesticus). A total of 96 three-day-old male broiler chickens (Ross × Ross) were divided into two groups. One group received a high energy (HE) diet and the other group received a low energy (LE) diet for 7 days. At 5 days of age, the chickens from each group were further divided into two sub-groups and received one of the following two treatments for 3 days: (1) subcutaneous injection of corticosterone, twice per day (CORT group; 2 mg of CORT/kg BW in corn oil) and (2) subcutaneous injection of corn oil, twice per day (Control/Sham treatment group). At 10 days of age, samples of blood, duodenum, jejunum, and ileum were obtained. Compared with the other three groups, the LE group treated with CORT had the lowest average daily gain (ADG) and the poorest feed conversion ratio (FCR, P < 0.05). Furthermore, CORT treatment decreased the relative weight (RW) of the bursa independent of the dietary energy level, but it decreased the RW of the thymus only in the chickens fed the LE diet. By contrast, CORT administration decreased the RW of the spleen only in the chickens fed the HE diet (P < 0.05). The plasma total protein, albumin, tumor necrosis factor alpha, interleukin 2 and immunoglobulin G (IgG) levels were affected by the CORT treatment (P < 0.05); however, these factors were not significantly affected by the dietary energy level. Toll-like receptor-5 mRNA level was down-regulated by CORT injection in the duodenum and ileum (P < 0.05) and showed a trend of down-regulation in the jejunum (P=0.0846). The present study showed that CORT treatment induced immunosuppressive effects on the innate immune system of broiler chickens, which were ameliorated by consumption of higher dietary energy. PMID:25803644

Autonomous sensor-transponder RFID with supply energy conditioning for object navigation systems

NASA Astrophysics Data System (ADS)

Skoczylas, M.; Kamuda, K.; Jankowski-Mihułowicz, P.; Kalita, W.; Weglarski, Mariusz

2014-08-01

The properties of energy conditioning electrical circuits that are developed for powering additional functional blocks of autonomous RFID transponders working in the HF band have been analyzed and presented in the paper. The concept of autonomy is realized by implementing extra functions in the typical transponder. First of all, the autonomous system should harvest energy, e.g. from the electromagnetic field of read/write devices but also the possibility of gathering information about environment should be available, e.g. by measuring different kind of physical quantities. In such an electrical device, the crucial problem consists in energy conditioning because the output voltage-current characteristic of an front-end (antenna with matching and harvesting circuit) as well as the total and instantaneous power load generated by internal circuits are strongly dependent on a realized function but also on energy and communication conditions in the RFID interface. The properly designed solution should improve harvesting efficiency, current leakage of supply storage, matching between antenna and input circuits, in order to save energy and increase operating time in such a battery-free system. The authors present methods how to increase the autonomous operation time even at advanced measuring algorithms. The measuring system with wide spectrum of sensors dedicated for different quantities (physical, chemical, etc.) has also been presented. The results of model calculations and experimental verifications have been also discussed on the basis of investigations conducted in the unique laboratory stand of object navigation systems.

The Interaction of Turbulence with Parallel and Perpendicular Shocks: Theory and Observations at 1 au

NASA Astrophysics Data System (ADS)

Adhikari, L.; Zank, G. P.; Hunana, P.; Hu, Q.

2016-12-01

Shocks are thought to be responsible for the amplification of turbulence as well as for generating turbulence throughout the heliosphere. We study the interaction of turbulence with parallel and perpendicular shock waves using the six-coupled-equation turbulence transport model of Zank et al. We model a 1D stationary shock wave using a hyperbolic tangent function and the Rankine-Hugoniot conditions for both a reduced model with four coupled equations and the full model. Eight quasi-parallel and five quasi-perpendicular events in the WIND spacecraft data sets are identified, and we compute the fluctuating magnetic and kinetic energy, the energy in forward and backward propagating modes, the total turbulent energy, the normalized residual energy, and the normalized cross helicity upstream and downstream of the observed shocks. We compare the observed fitted values upstream and downstream of the shock with numerical solutions to our model equations. The comparison shows that our theoretical results are in reasonable agreement with observations for both quasi-parallel and perpendicular shocks. We find that (1) the total turbulent energy, the energy in forward and backward propagating modes, and the normalized residual energy increase across the shock, (2) the normalized cross helicity increases or decreases across the shock, and (3) the correlation length increases upstream and downstream of the shock, and slightly flattens or decreases across the shock.

THE INTERACTION OF TURBULENCE WITH PARALLEL AND PERPENDICULAR SHOCKS: THEORY AND OBSERVATIONS AT 1 au

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, L.; Zank, G. P.; Hunana, P.

Shocks are thought to be responsible for the amplification of turbulence as well as for generating turbulence throughout the heliosphere. We study the interaction of turbulence with parallel and perpendicular shock waves using the six-coupled-equation turbulence transport model of Zank et al. We model a 1D stationary shock wave using a hyperbolic tangent function and the Rankine–Hugoniot conditions for both a reduced model with four coupled equations and the full model. Eight quasi-parallel and five quasi-perpendicular events in the WIND spacecraft data sets are identified, and we compute the fluctuating magnetic and kinetic energy, the energy in forward and backwardmore » propagating modes, the total turbulent energy, the normalized residual energy, and the normalized cross helicity upstream and downstream of the observed shocks. We compare the observed fitted values upstream and downstream of the shock with numerical solutions to our model equations. The comparison shows that our theoretical results are in reasonable agreement with observations for both quasi-parallel and perpendicular shocks. We find that (1) the total turbulent energy, the energy in forward and backward propagating modes, and the normalized residual energy increase across the shock, (2) the normalized cross helicity increases or decreases across the shock, and (3) the correlation length increases upstream and downstream of the shock, and slightly flattens or decreases across the shock.« less

Improvements in knee biomechanics during walking are associated with increased physical activity after total knee arthroplasty.

PubMed

Arnold, John B; Mackintosh, Shylie; Olds, Timothy S; Jones, Sara; Thewlis, Dominic

2015-12-01

Total knee arthroplasty (TKA) in people with knee osteoarthritis increases knee-specific and general physical function, but it has not been established if there is a relationship between changes in these elements of functional ability. This study investigated changes and relationships between knee biomechanics during walking, physical activity, and use of time after TKA. Fifteen people awaiting TKA underwent 3D gait analysis before and six months after surgery. Physical activity and use of time were determined in free-living conditions from a high resolution 24-h activity recall. After surgery, participants displayed significant improvements in sagittal plane knee biomechanics and improved their physical activity profiles, standing for 105 more minutes (p=0.001) and performing 64 min more inside chores on average per day (p=0.008). Changes in sagittal plane knee range of motion (ROM) and peak knee flexion positively correlated with changes in total daily energy expenditure, time spent undertaking moderate to vigorous physical activity, inside chores and passive transport (r=0.52-0.66, p=0.005-0.047). Restoration of knee function occurs in parallel and is associated with improvements in physical activity and use of time after TKA. Increased functional knee ROM is required to support improvements in total and context specific physical activity. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Effects of almond consumption on the post-lunch dip and long-term cognitive function in energy-restricted overweight and obese adults.

PubMed

Dhillon, Jaapna; Tan, Sze-Yen; Mattes, Richard D

2017-02-01

The post-lunch dip in cognition is a well-established phenomenon of decreased alertness, memory and vigilance after lunch consumption. Lunch composition reportedly influences the post-lunch dip. Moreover, dieting is associated with cognitive function impairments. The negative effects of dieting have been reversed with nut-supplemented diets. The aims of this study were to (1) evaluate the acute effect of an almond-enriched high-fat lunch or high-carbohydrate lunch on the post-lunch decline in cognitive function, and (2) evaluate the effects of chronic almond consumption as part of an energy-restricted diet on the memory and attention domains of cognitive function. In total, eighty-six overweight and obese adults were randomised to consume either an almond-enriched diet (AED) or a nut-free control diet (NFD) over a 12-week weight loss intervention. Participants were also randomised to receive either an almond-enriched high-fat lunch (A-HFL) (>55 % energy from fat, almonds contributing 70-75 % energy) or a high-carbohydrate lunch (HCL) (>85 % energy from carbohydrates) at the beginning and end of the weight loss intervention. Memory and attention performance indices decreased after lunch consumption (P<0·001). The A-HFL group ameliorated the decline in memory scores by 57·7 % compared with the HCL group (P=0·004). Both lunch groups had similar declines in attention. Moreover, memory and attention performance indices increased after the 12-week intervention period (P<0·05) with no difference between the AED and NFD groups. In conclusion, almond consumption at a midday meal can reduce the post-lunch dip in memory. However, long-term almond consumption may not further improve cognitive function outcomes in a weight loss intervention.

General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

PubMed

Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

2015-04-07

This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid

NASA Astrophysics Data System (ADS)

Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

2015-02-01

In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

Geometric phase effects in the ultracold D + HD $$ \\rightarrow $$ D + HD and D + HD $$\\leftrightarrow $$ H + D 2 reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kendrick, Brian Kent; Hazra, Jisha; Balakrishnan, Naduvaluth

The results of accurate quantum reactive scattering calculations for the D + HD(v = 4, j = 0)more » $$\\to $$ D + HD($$v^{\\prime} $$, $$j^{\\prime} $$), D + HD(v = 4, j = 0) $$\\to $$ H + D2($$v^{\\prime} $$, $$j^{\\prime} $$) and H + D2(v = 4, j = 0) $$\\to $$ D + HD($$v^{\\prime} $$, $$j^{\\prime} $$) reactions are presented for collision energies between $$1\\,\\mu {\\rm{K}}$$ and $$100\\,{\\rm{K}}$$. The ab initio BKMP2 PES for the ground electronic state of H3 is used and all values of total angular momentum between $J=0-4$ are included. The general vector potential approach is used to include the geometric phase. The rotationally resolved, vibrationally resolved, and total reaction rate coefficients are reported as a function of collision energy. Rotationally resolved differential cross sections are also reported as a function of collision energy and scattering angle. Large geometric phase effects appear in the ultracold reaction rate coefficients which result in a significant enhancement or suppression of the rate coefficient (up to 3 orders of magnitude) relative to calculations which ignore the geometric phase. The results are interpreted using a new quantum interference mechanism which is unique to ultracold collisions. Significant effects of the geometric phase also appear in the rotationally resolved differential cross sections which lead to a very different oscillatory structure in both energy and scattering angle. Several shape resonances occur in the 1–$$10\\,{\\rm{K}}$$ energy range and the geometric phase is shown to significantly alter the predicted resonance spectrum. The geometric phase effects and ultracold rate coefficients depend sensitively on the nuclear spin. Furthermore, experimentalists may be able to control the reaction by the selection of a particular nuclear spin state.« less

Geometric phase effects in the ultracold D + HD $$ \\rightarrow $$ D + HD and D + HD $$\\leftrightarrow $$ H + D 2 reactions

DOE PAGES

Kendrick, Brian Kent; Hazra, Jisha; Balakrishnan, Naduvaluth

2016-12-15

The results of accurate quantum reactive scattering calculations for the D + HD(v = 4, j = 0)more » $$\\to $$ D + HD($$v^{\\prime} $$, $$j^{\\prime} $$), D + HD(v = 4, j = 0) $$\\to $$ H + D2($$v^{\\prime} $$, $$j^{\\prime} $$) and H + D2(v = 4, j = 0) $$\\to $$ D + HD($$v^{\\prime} $$, $$j^{\\prime} $$) reactions are presented for collision energies between $$1\\,\\mu {\\rm{K}}$$ and $$100\\,{\\rm{K}}$$. The ab initio BKMP2 PES for the ground electronic state of H3 is used and all values of total angular momentum between $J=0-4$ are included. The general vector potential approach is used to include the geometric phase. The rotationally resolved, vibrationally resolved, and total reaction rate coefficients are reported as a function of collision energy. Rotationally resolved differential cross sections are also reported as a function of collision energy and scattering angle. Large geometric phase effects appear in the ultracold reaction rate coefficients which result in a significant enhancement or suppression of the rate coefficient (up to 3 orders of magnitude) relative to calculations which ignore the geometric phase. The results are interpreted using a new quantum interference mechanism which is unique to ultracold collisions. Significant effects of the geometric phase also appear in the rotationally resolved differential cross sections which lead to a very different oscillatory structure in both energy and scattering angle. Several shape resonances occur in the 1–$$10\\,{\\rm{K}}$$ energy range and the geometric phase is shown to significantly alter the predicted resonance spectrum. The geometric phase effects and ultracold rate coefficients depend sensitively on the nuclear spin. Furthermore, experimentalists may be able to control the reaction by the selection of a particular nuclear spin state.« less

Theoretical and experimental studies on the corrosion inhibition potentials of some purines for aluminum in 0.1 M HCl

PubMed Central

Eddy, Nnabuk O.; Momoh-Yahaya, H.; Oguzie, Emeka E.

2014-01-01

Experimental aspect of the corrosion inhibition potential of adenine (AD), guanine (GU) and, hypoxanthine (HYP) was carried out using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods while the theoretical aspect of the work was carried out by calculations of semi-empirical parameters (for AM1, MNDO, CNDO, PM3 and RM1 Hamiltonians), Fukui functions and inhibitor–metal interaction energies. Results obtained from the experimental studies were in good agreement and indicated that adenine (AD), guanine (GU) and hypoxanthine (HYP) are good adsorption inhibitors for the corrosion of aluminum in solutions of HCl. Data obtained from electrochemical experiment revealed that the studied purines functioned by adsorption on the aluminum/HCl interface and inhibited the cathodic half reaction to a greater extent and anodic half reaction to a lesser extent. The adsorption of the purines on the metal surface was found to be exothermic and spontaneous. Deviation of the adsorption characteristics of the studied purines from the Langmuir adsorption model was compensated by the fitness of Flory Huggins and El Awardy et al. adsorption models. Quantum chemical studies revealed that the experimental inhibition efficiencies of the studied purines are functions of some quantum chemical parameters including total energy of the molecules (TE), energy gap (EL–H), electronic energy of the molecule (EE), dipole moment and core–core repulsion energy (CCR). Fukui functions analysis through DFT and MP2 theories indicated slight complications and unphysical results. However, results obtained from calculated Huckel charges, molecular orbital and interaction energies, the adsorption of the inhibitors proceeded through the imine nitrogen (N5) in GU, emanine nitrogen (N7) in AD and the pyridine nitrogen (N5) in HPY. PMID:25750754

Theoretical and experimental studies on the corrosion inhibition potentials of some purines for aluminum in 0.1 M HCl.

PubMed

Eddy, Nnabuk O; Momoh-Yahaya, H; Oguzie, Emeka E

2015-03-01

Experimental aspect of the corrosion inhibition potential of adenine (AD), guanine (GU) and, hypoxanthine (HYP) was carried out using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods while the theoretical aspect of the work was carried out by calculations of semi-empirical parameters (for AM1, MNDO, CNDO, PM3 and RM1 Hamiltonians), Fukui functions and inhibitor-metal interaction energies. Results obtained from the experimental studies were in good agreement and indicated that adenine (AD), guanine (GU) and hypoxanthine (HYP) are good adsorption inhibitors for the corrosion of aluminum in solutions of HCl. Data obtained from electrochemical experiment revealed that the studied purines functioned by adsorption on the aluminum/HCl interface and inhibited the cathodic half reaction to a greater extent and anodic half reaction to a lesser extent. The adsorption of the purines on the metal surface was found to be exothermic and spontaneous. Deviation of the adsorption characteristics of the studied purines from the Langmuir adsorption model was compensated by the fitness of Flory Huggins and El Awardy et al. adsorption models. Quantum chemical studies revealed that the experimental inhibition efficiencies of the studied purines are functions of some quantum chemical parameters including total energy of the molecules (TE), energy gap (E L-H), electronic energy of the molecule (EE), dipole moment and core-core repulsion energy (CCR). Fukui functions analysis through DFT and MP2 theories indicated slight complications and unphysical results. However, results obtained from calculated Huckel charges, molecular orbital and interaction energies, the adsorption of the inhibitors proceeded through the imine nitrogen (N5) in GU, emanine nitrogen (N7) in AD and the pyridine nitrogen (N5) in HPY.

The RPA Atomization Energy Puzzle.

PubMed

Ruzsinszky, Adrienn; Perdew, John P; Csonka, Gábor I

2010-01-12

There is current interest in the random phase approximation (RPA), a "fifth-rung" density functional for the exchange-correlation energy. RPA has full exact exchange and constructs the correlation with the help of the unoccupied Kohn-Sham orbitals. In many cases (uniform electron gas, jellium surface, and free atom), the correction to RPA is a short-ranged effect that is captured by a local spin density approximation (LSDA) or a generalized gradient approximation (GGA). Nonempirical density functionals for the correction to RPA were constructed earlier at the LSDA and GGA levels (RPA+), but they are constructed here at the fully nonlocal level (RPA++), using the van der Waals density functional (vdW-DF) of Langreth, Lundqvist, and collaborators. While they make important and helpful corrections to RPA total and ionization energies of free atoms, they correct the RPA atomization energies of molecules by only about 1 kcal/mol. Thus, it is puzzling that RPA atomization energies are, on average, about 10 kcal/mol lower than those of accurate values from experiment. We find here that a hybrid of 50% Perdew-Burke-Ernzerhof GGA with 50% RPA+ yields atomization energies much more accurate than either one does alone. This suggests a solution to the puzzle: While the proper correction to RPA is short-ranged in some systems, its contribution to the correlation hole can spread out in a molecule with multiple atomic centers, canceling part of the spread of the exact exchange hole (more so than in RPA or RPA+), making the true exchange-correlation hole more localized than in RPA or RPA+. This effect is not captured even by the vdW-DF nonlocality, but it requires the different kind of full nonlocality present in a hybrid functional.

Energy coupling between the solar wind and the magnetosphere

NASA Technical Reports Server (NTRS)

Akasofu, S.-I.

1981-01-01

A description is given of the path leading to the first approximation expression for the solar wind-magnetosphere energy coupling function (epsilon), which correlates well with the total energy consumption rate (U sub T) of the magnetosphere. It is shown that epsilon is the primary factor controlling the time development of magnetospheric substorms and storms. The finding of this particular expression epsilon indicates how the solar wind couples its energy to the magnetosphere; the solar wind and the magnetosphere make up a dynamo. In fact, the power generated by the dynamo can be identified as epsilon through the use of a dimensional analysis. In addition, the finding of epsilon suggests that the magnetosphere is closer to a directly driven system than to an unloading system which stores the generated energy before converting it to substorm and storm energies. The finding of epsilon and its implications is considered to have significantly advanced and improved the understanding of magnetospheric processes.

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect.

PubMed

Xin, Mei-Ling; Yang, Jia-Wen; Li, Yu

2017-07-11

The reaction pathways of PCB-77 in the atmosphere with ·OH, O 2 , NO x , and 1 O 2 were inferred based on density functional theory calculations with the 6-31G* basis set. The structures the reactants, transition states, intermediates, and products were optimized. The energy barriers and reaction heats were obtained to determine the energetically favorable reaction pathways. To study the solvation effect, the energy barriers and reaction rates for PCB-77 with different polar and nonpolar solvents (cyclohexane, benzene, carbon tetrachloride, chloroform, acetone, dichloromethane, ethanol, methanol, acetonitrile, dimethylsulfoxide, and water) were calculated. The results showed that ·OH preferentially added to the C5 atom of PCB-77, which has no Cl atom substituent, to generate the intermediate IM5. This intermediate subsequently reacted with O 2 via pathway A to generate IM5a, with an energy barrier of 7.27 kcal/mol and total reaction rate of 8.45 × 10 -8  cm 3 /molecule s. Pathway B involved direct dehydrogenation of IM5 to produce the OH-PCBs intermediate IM5b, with an energy barrier of 28.49 kcal/mol and total reaction rate of 1.15 × 10 -5  cm 3 /molecule s. The most likely degradation pathway of PCB-77 in the atmosphere is pathway A to produce IM5a. The solvation effect results showed that cyclohexane, carbon tetrachloride, and benzene could reduce the reaction energy barrier of pathway A. Among these solvents, the solvation effect of benzene was the largest, and could reduce the total reaction energy barrier by 25%. Cyclohexane, carbon tetrachloride, benzene, dichloromethane, acetone, and ethanol could increase the total reaction rate of pathway A. The increase in the reaction rate of pathway A with benzene was 8%. The effect of solvents on oxidative degradation of PCB-77 in the atmosphere is important. Graphical abstract The reaction pathways of PCB-77 in the atmosphere with •OH, O2, NOx, and 1O2 were inferred based on density functional theory calculations with the 6-31G* basis set. Different polar and nonpolar solvents: cyclohexane, benzene, carbon tetrachloride, chloroform, acetone, dichloromethane, ethanol, methanol, acetonitrile, dimethylsulfoxide, and water were selected to study the solvation effect on the favorable reaction pathways. The investigated results showed what kind of pathway was most likely to occur and the solvent effect on the reaction pathway.

Leptin action through hypothalamic nitric oxide synthase-1-expressing neurons controls energy balance.

PubMed

Leshan, Rebecca L; Greenwald-Yarnell, Megan; Patterson, Christa M; Gonzalez, Ian E; Myers, Martin G

2012-05-01

Few effective measures exist to combat the worldwide obesity epidemic(1), and the identification of potential therapeutic targets requires a deeper understanding of the mechanisms that control energy balance. Leptin, an adipocyte-derived hormone that signals the long-term status of bodily energy stores, acts through multiple types of leptin receptor long isoform (LepRb)-expressing neurons (called here LepRb neurons) in the brain to control feeding, energy expenditure and endocrine function(2-4). The modest contributions to energy balance that are attributable to leptin action in many LepRb populations(5-9) suggest that other previously unidentified hypothalamic LepRb neurons have key roles in energy balance. Here we examine the role of LepRb in neuronal nitric oxide synthase (NOS1)-expressing LebRb (LepRb(NOS1)) neurons that comprise approximately 20% of the total hypothalamic LepRb neurons. Nos1(cre)-mediated genetic ablation of LepRb (Lepr(Nos1KO)) in mice produces hyperphagic obesity, decreased energy expenditure and hyperglycemia approaching that seen in whole-body LepRb-null mice. In contrast, the endocrine functions in Lepr(Nos1KO) mice are only modestly affected by the genetic ablation of LepRb in these neurons. Thus, hypothalamic LepRb(NOS1) neurons are a key site of action of the leptin-mediated control of systemic energy balance.

Effect of desvenlafaxine 50 mg and 100 mg on energy and lassitude in patients with major depressive disorder: A pooled analysis.

PubMed

Lam, Raymond W; Wajsbrot, Dalia B; Meier, Ellen; Pappadopulos, Elizabeth; Mackell, Joan A; Boucher, Matthieu

2017-09-01

Nine randomized, double-blind, placebo-controlled studies of major depressive disorder were pooled to evaluate the effects of desvenlafaxine 50- and 100-mg/d on energy and lassitude in adults with major depressive disorder ( n=4279). Changes from baseline to endpoint in 17-item Hamilton Rating Scale for Depression (HAM-D 17 ) Work and Activities, Retardation, and Somatic Symptoms General items, HAM-D 17 psychomotor retardation factor, and Montgomery-Åsberg Depression Rating Scale Lassitude item were analyzed with a mixed model for repeated measures analysis of variance. Associations between residual energy measures and functional impairment, based on the Sheehan Disability Scale, were modeled using stepwise multiple linear regression. Improvement from baseline was significantly greater for both desvenlafaxine doses versus placebo on all energy symptom outcomes at week 8 (all p⩽0.005). Both early improvement in HAM-D 17 psychomotor retardation at week 2 and residual energy symptoms at week 8 were associated with Sheehan Disability Scale total score at week 8 (all p⩽0.001). Among Sheehan Disability Scale remitters and responders, the HAM-D 17 psychomotor retardation score at week 8 was significantly lower with desvenlafaxine (both doses) than placebo. Desvenlafaxine 50 and 100 mg/d significantly improved energy and lassitude symptoms in patients with major depressive disorder. Both early improvement in energy and fewer residual energy symptoms were associated with functional improvement.

Intermolecular symmetry-adapted perturbation theory study of large organic complexes.

PubMed

Heßelmann, Andreas; Korona, Tatiana

2014-09-07

Binding energies for the complexes of the S12L database by Grimme [Chem. Eur. J. 18, 9955 (2012)] were calculated using intermolecular symmetry-adapted perturbation theory combined with a density-functional theory description of the interacting molecules. The individual interaction energy decompositions revealed no particular change in the stabilisation pattern as compared to smaller dimer systems at equilibrium structures. This demonstrates that, to some extent, the qualitative description of the interaction of small dimer systems may be extrapolated to larger systems, a method that is widely used in force-fields in which the total interaction energy is decomposed into atom-atom contributions. A comparison of the binding energies with accurate experimental reference values from Grimme, the latter including thermodynamic corrections from semiempirical calculations, has shown a fairly good agreement to within the error range of the reference binding energies.

Inelastic scattering matrix elements for the nonadiabatic collision B(2P1/2)+H2(1Sigmag+,j)<-->B(2P3/2)+H2(1Sigmag+,j').

PubMed

Weeks, David E; Niday, Thomas A; Yang, Sang H

2006-10-28

Inelastic scattering matrix elements for the nonadiabatic collision B(2P1/2)+H2(1Sigmag+,j)<-->B(2P3/2)+H2(1Sigmag+,j') are calculated using the time dependent channel packet method (CPM). The calculation employs 1 2A', 2 2A', and 1 2A" adiabatic electronic potential energy surfaces determined by numerical computation at the multireference configuration-interaction level [M. H. Alexander, J. Chem. Phys. 99, 6041 (1993)]. The 1 2A' and 2 2A', adiabatic electronic potential energy surfaces are transformed to yield diabatic electronic potential energy surfaces that, when combined with the total B+H2 rotational kinetic energy, yield a set of effective potential energy surfaces [M. H. Alexander et al., J. Chem. Phys. 103, 7956 (1995)]. Within the framework of the CPM, the number of effective potential energy surfaces used for the scattering matrix calculation is then determined by the size of the angular momentum basis used as a representation. Twenty basis vectors are employed for these calculations, and the corresponding effective potential energy surfaces are identified in the asymptotic limit by the H2 rotor quantum numbers j=0, 2, 4, 6 and B electronic states 2Pja, ja=1/2, 3/2. Scattering matrix elements are obtained from the Fourier transform of the correlation function between channel packets evolving in time on these effective potential energy surfaces. For these calculations the H2 bond length is constrained to a constant value of req=1.402 a.u. and state to state scattering matrix elements corresponding to a total angular momentum of J=1/2 are discussed for j=0<-->j'=0,2,4 and 2P1/2<-->2P1/2, 2P3/2 over a range of total energy between 0.0 and 0.01 a.u.

Achieving DFT accuracy with a machine-learning interatomic potential: Thermomechanics and defects in bcc ferromagnetic iron

NASA Astrophysics Data System (ADS)

Dragoni, Daniele; Daff, Thomas D.; Csányi, Gábor; Marzari, Nicola

2018-01-01

We show that the Gaussian Approximation Potential (GAP) machine-learning framework can describe complex magnetic potential energy surfaces, taking ferromagnetic iron as a paradigmatic challenging case. The training database includes total energies, forces, and stresses obtained from density-functional theory in the generalized-gradient approximation, and comprises approximately 150,000 local atomic environments, ranging from pristine and defected bulk configurations to surfaces and generalized stacking faults with different crystallographic orientations. We find the structural, vibrational, and thermodynamic properties of the GAP model to be in excellent agreement with those obtained directly from first-principles electronic-structure calculations. There is good transferability to quantities, such as Peierls energy barriers, which are determined to a large extent by atomic configurations that were not part of the training set. We observe the benefit and the need of using highly converged electronic-structure calculations to sample a target potential energy surface. The end result is a systematically improvable potential that can achieve the same accuracy of density-functional theory calculations, but at a fraction of the computational cost.

Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism

NASA Astrophysics Data System (ADS)

Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.

2014-11-01

The Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an efficient site-centered, electronic-structure technique for addressing an assembly of N scatterers. Wave functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax=(l,mmax), while scattering matrices, which determine spectral properties, are truncated at Lt r=(l,mt r) where phase shifts δl >ltr are negligible. Historically, Lmax is set equal to Lt r, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax>Lt r with δl >ltr set to zero [X.-G. Zhang and W. H. Butler, Phys. Rev. B 46, 7433 (1992), 10.1103/PhysRevB.46.7433]. We present a numerically efficient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N (ltr+1 ) 2 ] and includes higher-L contributions via linear algebra [R2 process with rank N (lmax+1) 2 ]. The augmented-KKR approach yields properly normalized wave functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe, and L 1 0 CoPt and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Lt r.

Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism

DOE PAGES

Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; ...

2014-11-04

Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number L max = (l,m) max, while scattering matrices, which determine spectral properties, are truncated at L tr = (l,m) tr where phase shifts δl>l tr are negligible. Historically, L max is set equal to L tr, which is correct for large enough L max but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for L maxmore » > L tr with δl>l tr set to zero [Zhang and Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R 3 process with rank N(l tr + 1) 2] and includes higher-L contributions via linear algebra [R 2 process with rank N(l max +1) 2]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L1 0 CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus L max for a given L tr.« less

Quantitative Imaging of Energy Expenditure in Human Brain

PubMed Central

Zhu, Xiao-Hong; Qiao, Hongyan; Du, Fei; Xiong, Qiang; Liu, Xiao; Zhang, Xiaoliang; Ugurbil, Kamil; Chen, Wei

2012-01-01

Despite the essential role of the brain energy generated from ATP hydrolysis in supporting cortical neuronal activity and brain function, it is challenging to noninvasively image and directly quantify the energy expenditure in the human brain. In this study, we applied an advanced in vivo 31P MRS imaging approach to obtain regional cerebral metabolic rates of high-energy phosphate reactions catalyzed by ATPase (CMRATPase) and creatine kinase (CMRCK), and to determine CMRATPase and CMRCK in pure grey mater (GM) and white mater (WM), respectively. It was found that both ATPase and CK rates are three times higher in GM than WM; and CMRCK is seven times higher than CMRATPase in GM and WM. Among the total brain ATP consumption in the human cortical GM and WM, 77% of them are used by GM in which approximately 96% is by neurons. A single cortical neuron utilizes approximately 4.7 billion ATPs per second in a resting human brain. This study demonstrates the unique utility of in vivo 31P MRS imaging modality for direct imaging of brain energy generated from ATP hydrolysis, and provides new insights into the human brain energetics and its role in supporting neuronal activity and brain function. PMID:22487547

The vibrational spectroscopic studies and molecular property analysis of L-Phenylalanine using quantum chemical method

NASA Astrophysics Data System (ADS)

Borah, Mukunda Madhab; Devi, Th. Gomti

2017-05-01

In the present work, L-phenylalanine is studied using the experimental and theoretical methods. The spectral characterization of the molecule has been done using Raman, FTIR, Hartee-Fock(HF), density functional theory (DFT) and vibrational energy distribution analysis (VEDA) calculation. The optimization of the molecule has been studied using basis set HF/6-31G(d,p) and B3LYP/6-31G(d,p) for Hartree Fock and density functional theory calculation. The complete vibrational assignment of the molecule in monomer and dimer states have been attempted. The potential energy distribution and normal mode analysis are also carried out to determine the contributions of bond oscillators in each normal mode. The molecular geometry, HOMO-LUMO energy gap, molecular hardness (η), ionization energy (IE), electron affinity (EA), total energy and dipole moment were determined from the calculated data. The observed experimental and the scaled theoretical results are compared and found to be in good agreement. The vibrational assignment of molecule in different dimer states has also been done using SERS data and better correlated Raman peaks are observed as compare to normal Raman technique.

Capturing RNA Folding Free Energy with Coarse-Grained Molecular Dynamics Simulations

PubMed Central

Bell, David R.; Cheng, Sara Y.; Salazar, Heber; Ren, Pengyu

2017-01-01

We introduce a coarse-grained RNA model for molecular dynamics simulations, RACER (RnA CoarsE-gRained). RACER achieves accurate native structure prediction for a number of RNAs (average RMSD of 2.93 Å) and the sequence-specific variation of free energy is in excellent agreement with experimentally measured stabilities (R2 = 0.93). Using RACER, we identified hydrogen-bonding (or base pairing), base stacking, and electrostatic interactions as essential driving forces for RNA folding. Also, we found that separating pairing vs. stacking interactions allowed RACER to distinguish folded vs. unfolded states. In RACER, base pairing and stacking interactions each provide an approximate stability of 3–4 kcal/mol for an A-form helix. RACER was developed based on PDB structural statistics and experimental thermodynamic data. In contrast with previous work, RACER implements a novel effective vdW potential energy function, which led us to re-parameterize hydrogen bond and electrostatic potential energy functions. Further, RACER is validated and optimized using a simulated annealing protocol to generate potential energy vs. RMSD landscapes. Finally, RACER is tested using extensive equilibrium pulling simulations (0.86 ms total) on eleven RNA sequences (hairpins and duplexes). PMID:28393861

Water 16-mers and hexamers: assessment of the three-body and electrostatically embedded many-body approximations of the correlation energy or the nonlocal energy as ways to include cooperative effects.

PubMed

Qi, Helena W; Leverentz, Hannah R; Truhlar, Donald G

2013-05-30

This work presents a new fragment method, the electrostatically embedded many-body expansion of the nonlocal energy (EE-MB-NE), and shows that it, along with the previously proposed electrostatically embedded many-body expansion of the correlation energy (EE-MB-CE), produces accurate results for large systems at the level of CCSD(T) coupled cluster theory. We primarily study water 16-mers, but we also test the EE-MB-CE method on water hexamers. We analyze the distributions of two-body and three-body terms to show why the many-body expansion of the electrostatically embedded correlation energy converges faster than the many-body expansion of the entire electrostatically embedded interaction potential. The average magnitude of the dimer contributions to the pairwise additive (PA) term of the correlation energy (which neglects cooperative effects) is only one-half of that of the average dimer contribution to the PA term of the expansion of the total energy; this explains why the mean unsigned error (MUE) of the EE-PA-CE approximation is only one-half of that of the EE-PA approximation. Similarly, the average magnitude of the trimer contributions to the three-body (3B) term of the EE-3B-CE approximation is only one-fourth of that of the EE-3B approximation, and the MUE of the EE-3B-CE approximation is one-fourth that of the EE-3B approximation. Finally, we test the efficacy of two- and three-body density functional corrections. One such density functional correction method, the new EE-PA-NE method, with the OLYP or the OHLYP density functional (where the OHLYP functional is the OptX exchange functional combined with the LYP correlation functional multiplied by 0.5), has the best performance-to-price ratio of any method whose computational cost scales as the third power of the number of monomers and is competitive in accuracy in the tests presented here with even the electrostatically embedded three-body approximation.

Non-Born-Oppenheimer calculations of the pure vibrational spectrum of HeH+.

PubMed

Pavanello, Michele; Bubin, Sergiy; Molski, Marcin; Adamowicz, Ludwik

2005-09-08

Very accurate calculations of the pure vibrational spectrum of the HeH(+) ion are reported. The method used does not assume the Born-Oppenheimer approximation, and the motion of both the electrons and the nuclei are treated on equal footing. In such an approach the vibrational motion cannot be decoupled from the motion of electrons, and thus the pure vibrational states are calculated as the states of the system with zero total angular momentum. The wave functions of the states are expanded in terms of explicitly correlated Gaussian basis functions multipled by even powers of the internuclear distance. The calculations yielded twelve bound states and corresponding eleven transition energies. Those are compared with the pure vibrational transition energies extracted from the experimental rovibrational spectrum.

Three-level mixing model for nuclear chiral rotation: Role of the planar component

NASA Astrophysics Data System (ADS)

Chen, Q. B.; Starosta, K.; Koike, T.

2018-04-01

Three- and two-level mixing models are proposed to understand the doubling of states at the same spin and parity in triaxially deformed atomic nuclei with odd numbers of protons and neutrons. The particle-rotor model for such nuclei is solved using the newly proposed basis which couples angular momenta of two valence nucleons and the rotating triaxial mean field into left-handed |L > , right-handed |R > , and planar |P > configurations. The presence and impact of the planar component is investigated as a function of the total spin for mass A ≈130 nuclei with the valence h11 /2 proton particle, valence h11 /2 neutron hole, and the maximum difference between principal axes allowed by the quadrupole deformation of the mean field. It is concluded that at each spin value the higher energy member of a doublet of states is built on the antisymmetric combination of |L > and |R > and is free of the |P > component, indicating that it is of pure chiral geometry. For the lower energy member of the doublet, the contribution of the |P > component to the eigenfunction first decreases and then increases as a function of the total spin. This trend as well as the energy splitting between the doublet states are both determined by the Hamiltonian matrix elements between the planar (|P > ) and nonplanar (|L > and |R > ) subspaces of the full Hilbert space.

Interannual Variability of Fisheries Economic Returns and Energy Ratios Is Mostly Explained by Gear Type

PubMed Central

Trenkel, Verena M.; Daurès, Fabienne; Rochet, Marie-Joëlle; Lorance, Pascal

2013-01-01

According to portfolio theory applied to fisheries management, economic returns are stabilised by harvesting in a portfolio stocks of species whose returns are negatively correlated and for which the portfolio economic return variance is smaller than the sum of stock specific return variances. Also, variability is expected to decrease with portfolio width. Using a range of indicators, these predictions were tested for the French fishing fleets in the Bay of Biscay (Northeast Atlantic) during the period 2001–2009. For this, vessels were grouped into eight fishing fleets based on the gears used and exploited species were grouped into five functional groups. The portfolio width of fleets ranged from 1–3 functional groups, or 4–19 species. Economic fleet returns (sale revenues minus fishing costs) varied strongly between years; the interannual variability was independent of portfolio width (species or functional groups). Energy ratio expressed by the ratio between fuel energy used for fishing and energy contained in landings varied from 0.3 for purse seines to 9.7 for trawlers using bottom trawls alone or in combination with pelagic trawls independent of portfolio width. Interannual variability in total sale revenues was larger than the sum of species specific sales revenue variability, except for fleets using hooks and pelagic trawlers; it increased with the number of species exploited. In conclusion, the interannual variability of economic returns or energy ratios of French fisheries in the Bay of Biscay did not decrease with the number of species or functional groups exploited, though it varied between fleets. PMID:23922951

Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

NASA Astrophysics Data System (ADS)

Merker, L.; Costi, T. A.

2012-08-01

We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat Cimp to be calculated accurately from local static correlation functions; specifically via Cimp=(∂Eionic)/(∂T)+(1)/(2)(∂Ehyb)/(∂T), where Eionic and Ehyb are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to Cimp. For the nondegenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high-temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two-state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The approach could also be of interest within other impurity solvers, for example, within quantum Monte Carlo techniques.

Experimental Energy Levels and Partition Function of the 12C2 Molecule

NASA Astrophysics Data System (ADS)

Furtenbacher, Tibor; Szabó, István; Császár, Attila G.; Bernath, Peter F.; Yurchenko, Sergei N.; Tennyson, Jonathan

2016-06-01

The carbon dimer, the 12C2 molecule, is ubiquitous in astronomical environments. Experimental-quality rovibronic energy levels are reported for 12C2, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. The determination utilizes the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. The 23,343 transitions measured experimentally and validated within this study determine 5699 rovibronic energy levels, 1325, 4309, and 65 levels for the singlet, triplet, and quintet states investigated, respectively. The MARVEL analysis provides rovibronic energies for six singlet, six triplet, and two quintet electronic states. For example, the lowest measurable energy level of the {{a}}{}3{{{\\Pi }}}{{u}} state, corresponding to the J = 2 total angular momentum quantum number and the F 1 spin-multiplet component, is 603.817(5) cm-1. This well-determined energy difference should facilitate observations of singlet-triplet intercombination lines, which are thought to occur in the interstellar medium and comets. The large number of highly accurate and clearly labeled transitions that can be derived by combining MARVEL energy levels with computed temperature-dependent intensities should help a number of astrophysical observations as well as corresponding laboratory measurements. The experimental rovibronic energy levels, augmented, where needed, with ab initio variational ones based on empirically adjusted and spin-orbit coupled potential energy curves obtained using the Duo code, are used to obtain a highly accurate partition function, and related thermodynamic data, for 12C2 up to 4000 K.

Uncertainty Estimate for the Outdoor Calibration of Solar Pyranometers: A Metrologist Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, I.; Myers, D.; Stoffel, T.

2008-12-01

Pyranometers are used outdoors to measure solar irradiance. By design, this type of radiometer can measure the; total hemispheric (global) or diffuse (sky) irradiance when the detector is unshaded or shaded from the sun disk, respectively. These measurements are used in a variety of applications including solar energy conversion, atmospheric studies, agriculture, and materials science. Proper calibration of pyranometers is essential to ensure measurement quality. This paper describes a step-by-step method for calculating and reporting the uncertainty of the calibration, using the guidelines of the ISO 'Guide to the Expression of Uncertainty in Measurement' or GUM, that is applied tomore » the pyranometer; calibration procedures used at the National Renewable Energy Laboratory (NREL). The NREL technique; characterizes a responsivity function of a pyranometer as a function of the zenith angle, as well as reporting a single; calibration responsivity value for a zenith angle of 45 ..deg... The uncertainty analysis shows that a lower uncertainty can be achieved by using the response function of a pyranometer determined as a function of zenith angle, in lieu of just using; the average value at 45..deg... By presenting the contribution of each uncertainty source to the total uncertainty; users will be able to troubleshoot and improve their calibration process. The uncertainty analysis method can also be used to determine the uncertainty of different calibration techniques and applications, such as deriving the uncertainty of field measurements.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.

Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number L max = (l,m) max, while scattering matrices, which determine spectral properties, are truncated at L tr = (l,m) tr where phase shifts δl>l tr are negligible. Historically, L max is set equal to L tr, which is correct for large enough L max but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for L maxmore » > L tr with δl>l tr set to zero [Zhang and Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R 3 process with rank N(l tr + 1) 2] and includes higher-L contributions via linear algebra [R 2 process with rank N(l max +1) 2]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L1 0 CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus L max for a given L tr.« less

Distributed Optimal Dispatch of Distributed Energy Resources Over Lossy Communication Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Junfeng; Yang, Tao; Wu, Di

In this paper, we consider the economic dispatch problem (EDP), where a cost function that is assumed to be strictly convex is assigned to each of distributed energy resources (DERs), over packet dropping networks. The goal of a standard EDP is to minimize the total generation cost while meeting total demand and satisfying individual generator output limit. We propose a distributed algorithm for solving the EDP over networks. The proposed algorithm is resilient against packet drops over communication links. Under the assumption that the underlying communication network is strongly connected with a positive probability and the packet drops are independentmore » and identically distributed (i.i.d.), we show that the proposed algorithm is able to solve the EDP. Numerical simulation results are used to validate and illustrate the main results of the paper.« less

Structure and energetics of Cr(CO)6 and Cr(CO)5

NASA Technical Reports Server (NTRS)

Barnes, Leslie A.; Liu, Bowen; Lindh, Roland

1993-01-01

The geometric structures and energetics of Cr(CO)6 and Cr(CO)5 are determined at the modified coupled-pair functional, single and double excitation coupled-cluster (CCSD), and CCSD(T) levels of theory. For Cr(CO)6, the structure and force constants for the totally symmetric representation are in good agreement with experimental data once basis set constants are taken into account. In the largest basis set at the CCSD(T) level of theory, the total binding energy of CR(CO)6 is estimated at around 140 kcal/mol, or about 86 percent of the experimental value. In contrast, the first bond energy of Cr(CO)6 is very well described at the CCSD(T) level of theory, with the best estimated value of 38 kcal/mol being within the experimental uncertainty.

Eclipse and noneclipse differential photoelectron flux.

NASA Technical Reports Server (NTRS)

Knudsen, W. C.; Sharp, G. W.

1972-01-01

Differential photoelectron flux in the energy range of 3 to 50 eV has been measured in the lower ionosphere both during the March 7, 1970, solar eclipse and during a period 24 hours earlier. The two measurements were made with identical retarding potential analyzers carried on Nike-Apache rocket flights to a peak altitude of approximately 180 km. The differential electron flux spectrum within totality on the eclipse flight had the same shape but was a factor of 10 smaller in magnitude than that measured on the control day at altitudes between 120 and 180 km, an expected result for an eclipse function decreasing to 1/10 at totality. The differential flux spectrum measured in full sun has the same general energy dependence as that reported by Doering et al. (1970) but is larger by a factor of 2 to 10, depending on altitude.

Nonsymbiotic Hemoglobin-2 Leads to an Elevated Energy State and to a Combined Increase in Polyunsaturated Fatty Acids and Total Oil Content When Overexpressed in Developing Seeds of Transgenic Arabidopsis Plants1[OA

PubMed Central

Vigeolas, Helene; Hühn, Daniela; Geigenberger, Peter

2011-01-01

Nonsymbiotic hemoglobins are ubiquitously expressed in plants and divided into two different classes based on gene expression pattern and oxygen-binding properties. Most of the published research has been on the function of class 1 hemoglobins. To investigate the role of class 2 hemoglobins, transgenic Arabidopsis (Arabidopsis thaliana) plants were generated overexpressing Arabidopsis hemoglobin-2 (AHb2) under the control of a seed-specific promoter. Overexpression of AHb2 led to a 40% increase in the total fatty acid content of developing and mature seeds in three subsequent generations. This was mainly due to an increase in the polyunsaturated C18:2 (ω-6) linoleic and C18:3 (ω-3) α-linolenic acids. Moreover, AHb2 overexpression led to an increase in the C18:2/C18:1 and C18:3/C18:2 ratios as well as in the C18:3 content in mol % of total fatty acids and in the unsaturation/saturation index of total seed lipids. The increase in fatty acid content was mainly due to a stimulation of the rate of triacylglycerol synthesis, which was attributable to a 3-fold higher energy state and a 2-fold higher sucrose content of the seeds. Under low external oxygen, AHb2 overexpression maintained an up to 5-fold higher energy state and prevented fermentation. This is consistent with AHb2 overexpression results in improved oxygen availability within developing seeds. In contrast to this, overexpression of class 1 hemoglobin did not lead to any significant increase in the metabolic performance of the seeds. These results provide evidence for a specific function of class 2 hemoglobin in seed oil production and in promoting the accumulation of polyunsaturated fatty acids by facilitating oxygen supply in developing seeds. PMID:21205621

Energetics and formation mechanism of borders between hexagonal boron nitride and graphene

NASA Astrophysics Data System (ADS)

Sawahata, Hisaki; Yamanaka, Ayaka; Maruyama, Mina; Okada, Susumu

2018-06-01

We studied the energetics of two-dimensional heterostructures consisting of hexagonal boron nitride (h-BN) and graphene with respect to the border structure and heterobond species using density functional theory. A BC heterobond is energetically preferable at the border between h-BN and graphene. We also found that the polarization at the zigzag border increases the total energy of the heterostructures. Competition between the bond formation energy and the polarization energy leads to chiral borders at which BC heterobonds are dominant. By taking the formation process of the heterostructures into account, the zigzag border with BC heterobonds is found to be preferentially synthesized from graphene edges under hydrogen-rich conditions.

Compatible, energy conserving, bounds preserving remap of hydrodynamic fields for an extended ALE scheme

DOE PAGES

Burton, Donald E.; Morgan, Nathaniel Ray; Charest, Marc Robert Joseph; ...

2017-11-22

From the very origins of numerical hydrodynamics in the Lagrangian work of von Neumann and Richtmyer [83], the issue of total energy conservation as well as entropy production has been problematic. Because of well known problems with mesh deformation, Lagrangian schemes have evolved into Arbitrary Lagrangian–Eulerian (ALE) methods [39] that combine the best properties of Lagrangian and Eulerian methods. Energy issues have persisted for this class of methods. We believe that fundamental issues of energy conservation and entropy production in ALE require further examination. The context of the paper is an ALE scheme that is extended in the sense thatmore » it permits cyclic or periodic remap of data between grids of the same or differing connectivity. The principal design goals for a remap method then consist of total energy conservation, bounded internal energy, and compatibility of kinetic energy and momentum. We also have secondary objectives of limiting velocity and stress in a non-directional manner, keeping primitive variables monotone, and providing a higher than second order reconstruction of remapped variables. Particularly, the new contributions fall into three categories associated with: energy conservation and entropy production, reconstruction and bounds preservation of scalar and tensor fields, and conservative remap of nonlinear fields. Our paper presents a derivation of the methods, details of implementation, and numerical results for a number of test problems. The methods requires volume integration of polynomial functions in polytopal cells with planar facets, and the requisite expressions are derived for arbitrary order.« less

Compatible, energy conserving, bounds preserving remap of hydrodynamic fields for an extended ALE scheme

NASA Astrophysics Data System (ADS)

Burton, D. E.; Morgan, N. R.; Charest, M. R. J.; Kenamond, M. A.; Fung, J.

2018-02-01

From the very origins of numerical hydrodynamics in the Lagrangian work of von Neumann and Richtmyer [83], the issue of total energy conservation as well as entropy production has been problematic. Because of well known problems with mesh deformation, Lagrangian schemes have evolved into Arbitrary Lagrangian-Eulerian (ALE) methods [39] that combine the best properties of Lagrangian and Eulerian methods. Energy issues have persisted for this class of methods. We believe that fundamental issues of energy conservation and entropy production in ALE require further examination. The context of the paper is an ALE scheme that is extended in the sense that it permits cyclic or periodic remap of data between grids of the same or differing connectivity. The principal design goals for a remap method then consist of total energy conservation, bounded internal energy, and compatibility of kinetic energy and momentum. We also have secondary objectives of limiting velocity and stress in a non-directional manner, keeping primitive variables monotone, and providing a higher than second order reconstruction of remapped variables. In particular, the new contributions fall into three categories associated with: energy conservation and entropy production, reconstruction and bounds preservation of scalar and tensor fields, and conservative remap of nonlinear fields. The paper presents a derivation of the methods, details of implementation, and numerical results for a number of test problems. The methods requires volume integration of polynomial functions in polytopal cells with planar facets, and the requisite expressions are derived for arbitrary order.

Statistical Characterization of 18650-Format Lithium-Ion Cell Thermal Runaway Energy Distributions

NASA Technical Reports Server (NTRS)

Walker, William Q.; Rickman, Steven; Darst, John; Finegan, Donal; Bayles, Gary; Darcy, Eric

2017-01-01

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh/kg) and moderate energy (200 Wh/kg) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 1/4m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.

Compatible, energy conserving, bounds preserving remap of hydrodynamic fields for an extended ALE scheme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, Donald E.; Morgan, Nathaniel Ray; Charest, Marc Robert Joseph

From the very origins of numerical hydrodynamics in the Lagrangian work of von Neumann and Richtmyer [83], the issue of total energy conservation as well as entropy production has been problematic. Because of well known problems with mesh deformation, Lagrangian schemes have evolved into Arbitrary Lagrangian–Eulerian (ALE) methods [39] that combine the best properties of Lagrangian and Eulerian methods. Energy issues have persisted for this class of methods. We believe that fundamental issues of energy conservation and entropy production in ALE require further examination. The context of the paper is an ALE scheme that is extended in the sense thatmore » it permits cyclic or periodic remap of data between grids of the same or differing connectivity. The principal design goals for a remap method then consist of total energy conservation, bounded internal energy, and compatibility of kinetic energy and momentum. We also have secondary objectives of limiting velocity and stress in a non-directional manner, keeping primitive variables monotone, and providing a higher than second order reconstruction of remapped variables. Particularly, the new contributions fall into three categories associated with: energy conservation and entropy production, reconstruction and bounds preservation of scalar and tensor fields, and conservative remap of nonlinear fields. Our paper presents a derivation of the methods, details of implementation, and numerical results for a number of test problems. The methods requires volume integration of polynomial functions in polytopal cells with planar facets, and the requisite expressions are derived for arbitrary order.« less

Free energy functionals for polarization fluctuations: Pekar factor revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinpajooh, Mohammadhasan; Newton, Marshall D.; Matyushov, Dmitry V.

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar’s perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parametermore » accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from simulations is numerically close to the Pekar factor. However, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found for the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).« less

Free energy functionals for polarization fluctuations: Pekar factor revisited

DOE PAGES

Dinpajooh, Mohammadhasan; Newton, Marshall D.; Matyushov, Dmitry V.

2017-02-13

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar’s perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parametermore » accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from simulations is numerically close to the Pekar factor. However, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found for the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).« less

Fourfold Clusters of Rovibrational Energies in H2Te Studied With an Ab Initio Potential Energy Function

NASA Technical Reports Server (NTRS)

Jensen, Per; Li, Yan; Hirsch, Gerhard; Buenker, Robert J.; Lee, Timothy J.; Arnold, James O. (Technical Monitor)

1994-01-01

We report an ab initio investigation of the cluster effect (i.e., the formation of nearly degenerate, four member groups of rotation-vibration energy levels at higher J and K(sub a). values) in the H2Te molecule. The potential energy function has been calculated ab initio at a total of 334 molecular geometries by means of the CCSD(T) method where the (1s-4f) core electrons of Te were described by an effective core potential. The values of the potential energy function obtained cover the region up to around 10,000/cm above the equilibrium energy. On the basis of the ab initio potential, the rotation-vibration energy spectra of H2Te-130 and its deuterated isotopomers have been calculated with the MORBID (Morse Oscillator Rigid Bender Internal Dynamics) Hamiltonian and computer program. In particular, we have calculated the rotational energy manifolds for J less than or = 40 in the vibrational ground state, the upsilon(sub 2) state, the "first triad" (the upsilon(sub l)/upsilon(sub 3)/2upsilon(sub 2) interacting vibrational states), and the "second triad" (the upsilon(sub 1) + upsilon(sub 2/upsilon(sub 2) + upsilon(sub 3)/3upsilon(sub 2) states) of H2Te-130. We find that the cluster formation in H2Te is very similar to those of of H2Se and H2S, which we have studied previously. However, contrary to semiclassical predictions, we do not determine any significant displacement of the clusters towards lower J values relative to H2Se. Hence the experimental observation of the cluster states in H2Te will be at least as difficult as in H2Se.

Free energy functionals for polarization fluctuations: Pekar factor revisited.

PubMed

Dinpajooh, Mohammadhasan; Newton, Marshall D; Matyushov, Dmitry V

2017-02-14

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar's perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from the simulations is numerically close to the Pekar factor. However, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found in the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).

Measurement and simulation of lineal energy distribution at the CERN high energy facility with a tissue equivalent proportional counter.

PubMed

Rollet, S; Autischer, M; Beck, P; Latocha, M

2007-01-01

The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

Calculation of the total electron excitation cross section in the Born approximation using Slater wave functions for the Li (2s yields 2p), Li (2s yields 3p), Na (3s yields 4p), Mg (3p yields 4s), Ca (4s yields 4p) and K (4s yields 4p) excitations. M.S. Thesis

NASA Technical Reports Server (NTRS)

Simsic, P. L.

1974-01-01

Excitation of neutral atoms by inelastic scattering of incident electrons in gaseous nebulae were investigated using Slater Wave functions to describe the initial and final states of the atom. Total cross sections using the Born Approximation are calculated for: Li(2s yields 2p), Na(3s yields 4p), k(4s yields 4p). The intensity of emitted radiation from gaseous nebulae is also calculated, and Maxwell distribution is employed to average the kinetic energy of electrons.

Using the charge-stabilization technique in the double ionization potential equation-of-motion calculations with dianion references.

PubMed

Kuś, Tomasz; Krylov, Anna I

2011-08-28

The charge-stabilization method is applied to double ionization potential equation-of-motion (EOM-DIP) calculations to stabilize unstable dianion reference functions. The auto-ionizing character of the dianionic reference states spoils the numeric performance of EOM-DIP limiting applications of this method. We demonstrate that reliable excitation energies can be computed by EOM-DIP using a stabilized resonance wave function instead of the lowest energy solution corresponding to the neutral + free electron(s) state of the system. The details of charge-stabilization procedure are discussed and illustrated by examples. The choice of optimal stabilizing Coulomb potential, which is strong enough to stabilize the dianion reference, yet, minimally perturbs the target states of the neutral, is the crux of the approach. Two algorithms of choosing optimal parameters of the stabilization potential are presented. One is based on the orbital energies, and another--on the basis set dependence of the total Hartree-Fock energy of the reference. Our benchmark calculations of the singlet-triplet energy gaps in several diradicals show a remarkable improvement of the EOM-DIP accuracy in problematic cases. Overall, the excitation energies in diradicals computed using the stabilized EOM-DIP are within 0.2 eV from the reference EOM spin-flip values. © 2011 American Institute of Physics

Energy density and rate limitations in structural composite supercapacitors

NASA Astrophysics Data System (ADS)

Snyder, J. F.; Gienger, E.; Wetzel, E. D.; Xu, K.

2012-06-01

The weight and volume of conventional energy storage technologies greatly limits their performance in mobile platforms. Traditional research efforts target improvements in energy density to reduce device size and mass. Enabling a device to perform additional functions, such as bearing mechanical load, is an alternative approach as long as the total mass efficiency exceeds that of the individual materials it replaces. Our research focuses on structural composites that function as batteries and supercapacitors. These multifunctional devices could be used to replace conventional structural components, such as vehicle frame elements, to provide significant system-level weight reductions and extend mission times. Our approach is to design structural properties directly into the electrolyte and electrode materials. Solid polymer electrolyte materials bind the system and transfer load to the fibers while conducting ions between the electrodes. Carbon fiber electrodes provide a route towards optimizing both energy storage and load-bearing capabilities, and may also obviate the need for a separate current collector. The components are being integrated using scalable, cost-effective composite processing techniques that are amenable to complex part shapes. Practical considerations of energy density and rate behavior are described here as they relate to materials used. Our results highlight the viability as well as the challenges of this multifunctional approach towards energy storage.

Geometrical, electronic, and magnetic properties of CunFe (n=1-12) clusters: A density functional study

NASA Astrophysics Data System (ADS)

Ling, Wang; Dong, Die; Shi-Jian, Wang; Zheng-Quan, Zhao

2015-01-01

The geometrical, electronic, and magnetic properties of small CunFe (n=1-12) clusters have been investigated by using density functional method B3LYP and LanL2DZ basis set. The structural search reveals that Fe atoms in low-energy CunFe isomers tend to occupy the position with the maximum coordination number. The ground state CunFe clusters possess planar structure for n=2-5 and three-dimensional (3D) structure for n=6-12. The electronic properties of CunFe clusters are analyzed through the averaged binding energy, the second-order energy difference and HOMO-LUMO energy gap. It is found that the magic numbers of stability are 1, 3, 7 and 9 for the ground state CunFe clusters. The energy gap of Fe-encapsulated cage clusters is smaller than that of other configurations. The Cu5Fe and Cu7Fe clusters have a very large energy gap (>2.4 eV). The vertical ionization potential (VIP), electron affinity (EA) and photoelectron spectra are also calculated and simulated theoretically for all the ground-state clusters. The magnetic moment analyses for the ground-state CunFe clusters show that Fe atom can enhance the magnetic moment of the host cluster and carries most of the total magnetic moment.

Attractive electron-electron interactions within robust local fitting approximations.

PubMed

Merlot, Patrick; Kjærgaard, Thomas; Helgaker, Trygve; Lindh, Roland; Aquilante, Francesco; Reine, Simen; Pedersen, Thomas Bondo

2013-06-30

An analysis of Dunlap's robust fitting approach reveals that the resulting two-electron integral matrix is not manifestly positive semidefinite when local fitting domains or non-Coulomb fitting metrics are used. We present a highly local approximate method for evaluating four-center two-electron integrals based on the resolution-of-the-identity (RI) approximation and apply it to the construction of the Coulomb and exchange contributions to the Fock matrix. In this pair-atomic resolution-of-the-identity (PARI) approach, atomic-orbital (AO) products are expanded in auxiliary functions centered on the two atoms associated with each product. Numerical tests indicate that in 1% or less of all Hartree-Fock and Kohn-Sham calculations, the indefinite integral matrix causes nonconvergence in the self-consistent-field iterations. In these cases, the two-electron contribution to the total energy becomes negative, meaning that the electronic interaction is effectively attractive, and the total energy is dramatically lower than that obtained with exact integrals. In the vast majority of our test cases, however, the indefiniteness does not interfere with convergence. The total energy accuracy is comparable to that of the standard Coulomb-metric RI method. The speed-up compared with conventional algorithms is similar to the RI method for Coulomb contributions; exchange contributions are accelerated by a factor of up to eight with a triple-zeta quality basis set. A positive semidefinite integral matrix is recovered within PARI by introducing local auxiliary basis functions spanning the full AO product space, as may be achieved by using Cholesky-decomposition techniques. Local completion, however, slows down the algorithm to a level comparable with or below conventional calculations. Copyright © 2013 Wiley Periodicals, Inc.

Revised Thomas-Fermi approximation for singular potentials

NASA Astrophysics Data System (ADS)

Dufty, James W.; Trickey, S. B.

2016-08-01

Approximations for the many-fermion free-energy density functional that include the Thomas-Fermi (TF) form for the noninteracting part lead to singular densities for singular external potentials (e.g., attractive Coulomb). This limitation of the TF approximation is addressed here by a formal map of the exact Euler equation for the density onto an equivalent TF form characterized by a modified Kohn-Sham potential. It is shown to be a "regularized" version of the Kohn-Sham potential, tempered by convolution with a finite-temperature response function. The resulting density is nonsingular, with the equilibrium properties obtained from the total free-energy functional evaluated at this density. This new representation is formally exact. Approximate expressions for the regularized potential are given to leading order in a nonlocality parameter, and the limiting behavior at high and low temperatures is described. The noninteracting part of the free energy in this approximation is the usual Thomas-Fermi functional. These results generalize and extend to finite temperatures the ground-state regularization by R. G. Parr and S. Ghosh [Proc. Natl. Acad. Sci. U.S.A. 83, 3577 (1986), 10.1073/pnas.83.11.3577] and by L. R. Pratt, G. G. Hoffman, and R. A. Harris [J. Chem. Phys. 88, 1818 (1988), 10.1063/1.454105] and formally systematize the finite-temperature regularization given by the latter authors.

Structure and Electronic Properties of Neutral and Negatively Charged RhBn Clusters (n = 3-10): A Density Functional Theory Study.

PubMed

Li, Peifang; Mei, Tingting; Lv, Linxia; Lu, Cheng; Wang, Weihua; Bao, Gang; Gutsev, Gennady L

2017-08-31

The geometrical structure and electronic properties of the neutral RhB n and singly negatively charged RhB n - clusters are obtained in the range of 3 ≤ n ≤ 10 using the unbiased CALYPSO structure search method and density functional theory (DFT). A combination of the PBE0 functional and the def2-TZVP basis set is used for determining global minima on potential energy surfaces of the Rh-doped B n clusters. The photoelectron spectra of the anions are simulated using the time-dependent density functional theory (TD-DFT) method. Good agreement between our simulated and experimentally obtained photoelectron spectra for RhB 9 - provides support to the validity of our theoretical method. The relative stabilities of the ground-state RhB n and RhB n - clusters are estimated using the calculated binding energies, second-order total energy differences, and HOMO-LUMO gaps. It is found that RhB 7 and RhB 8 - are the most stable species in the neutral and anionic series, respectively. The chemical bonding analysis reveals that the RhB 8 - cluster possesses two sets of delocalized σ and π bonds. In both cases, the Hückel 4N + 2 rule is fulfilled and this cluster possesses both σ and π aromaticities.

An extended hybrid density functional (X3LYP) with improved descriptions of nonbond interactions and thermodynamic properties of molecular systems.

PubMed

Xu, Xin; Zhang, Qingsong; Muller, Richard P; Goddard, William A

2005-01-01

We derive here the form for the exact exchange energy density for a density that decays with Gaussian-type behavior at long range. This functional is intermediate between the B88 and the PW91 exchange functionals. Using this modified functional to match the form expected for Gaussian densities, we propose the X3LYP extended functional. We find that X3LYP significantly outperforms Becke three parameter Lee-Yang-Parr (B3LYP) for describing van der Waals and hydrogen bond interactions, while performing slightly better than B3LYP for predicting heats of formation, ionization potentials, electron affinities, proton affinities, and total atomic energies as validated with the extended G2 set of atoms and molecules. Thus X3LYP greatly enlarges the field of applications for density functional theory. In particular the success of X3LYP in describing the water dimer (with R(e) and D(e) within the error bars of the most accurate determinations) makes it an excellent candidate for predicting accurate ligand-protein and ligand-DNA interactions. (c) 2005 American Institute of Physics.

Energy metabolism and nutrient oxidation in the pregnant mink (Mustela vison) as a model for other carnivores.

PubMed

Tauson, A H; Elnif, J; Hansen, N E

1994-12-01

The mink is a strict carnivore and a seasonal breeder, which may be used as an experimental model for other carnivores. The present investigation comprised a total of 44 balance experiments, each including a 24-h measurement of heat production by indirect calorimetry, carried out from mating until close to parturition. For observations with a nonprotein respiratory quotient between 0.7 and 1.0 (n = 42), quantitative oxidation of nutrients was calculated. The weight gain of the uterus during pregnancy was studied in 41 females killed either before mating, before implantation, after implantation or in mid or late true gestation, and energy retention was calculated. Heat production did not increase with advancing stage of gestation. Mean energy retention was low and in some individuals with repeated measurements even negative, indicating that part of the energy requirement for pregnancy may be supplied by mobilization of body reserves. This was reflected by a high level (42%) of fat oxidation in relation to total heat production. Protein oxidation accounted for 38% of heat production. The weight gain of the uterus during pregnancy could be described by logarithmic functions. Energy deposition in fetal tissue was low and only averaged approximately 350 kJ 47 d after mating.

Reexamining the role of the (n ,γ f ) process in the low-energy fission of 235U and 239Pu

NASA Astrophysics Data System (ADS)

Lynn, J. E.; Talou, P.; Bouland, O.

2018-06-01

The (n ,γ f ) process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on 235U and 239Pu. Observed fluctuations of the average prompt fission neutron multiplicity and average total γ -ray energy below 100-eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the M 1 transitions to the prefission γ -ray spectrum of 239Pu is explained by the dominant fission probabilities of 0+ and 2+ transition states, which can only be accessed from compound nucleus states formed by the interaction of s -wave neutrons with the target nucleus in its ground state, and decaying through M 1 transitions. The impact of an additional low-lying M 1 scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic-energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. Finally, calculations are extended to the fast energy range where (n ,γ f ) corrections can account for up to 3% of the total fission cross section and about 20% of the capture cross section.

wannier90: A tool for obtaining maximally-localised Wannier functions

NASA Astrophysics Data System (ADS)

Mostofi, Arash A.; Yates, Jonathan R.; Lee, Young-Su; Souza, Ivo; Vanderbilt, David; Marzari, Nicola

2008-05-01

We present wannier90, a program for calculating maximally-localised Wannier functions (MLWF) from a set of Bloch energy bands that may or may not be attached to or mixed with other bands. The formalism works by minimising the total spread of the MLWF in real space. This is done in the space of unitary matrices that describe rotations of the Bloch bands at each k-point. As a result, wannier90 is independent of the basis set used in the underlying calculation to obtain the Bloch states. Therefore, it may be interfaced straightforwardly to any electronic structure code. The locality of MLWF can be exploited to compute band-structure, density of states and Fermi surfaces at modest computational cost. Furthermore, wannier90 is able to output MLWF for visualisation and other post-processing purposes. Wannier functions are already used in a wide variety of applications. These include analysis of chemical bonding in real space; calculation of dielectric properties via the modern theory of polarisation; and as an accurate and minimal basis set in the construction of model Hamiltonians for large-scale systems, in linear-scaling quantum Monte Carlo calculations, and for efficient computation of material properties, such as the anomalous Hall coefficient. wannier90 is freely available under the GNU General Public License from http://www.wannier.org/. Program summaryProgram title: wannier90 Catalogue identifier: AEAK_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAK_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 556 495 No. of bytes in distributed program, including test data, etc.: 5 709 419 Distribution format: tar.gz Programming language: Fortran 90, perl Computer: any architecture with a Fortran 90 compiler Operating system: Linux, Windows, Solaris, AIX, Tru64 Unix, OSX RAM: 10 MB Word size: 32 or 64 Classification: 7.3 External routines:BLAS ( http://www/netlib.org/blas). LAPACK ( http://www.netlib.org/lapack). Both available under open-source licenses. Nature of problem: Obtaining maximally-localised Wannier functions from a set of Bloch energy bands that may or may not be entangled. Solution method: In the case of entangled bands, the optimally-connected subspace of interest is determined by minimising a functional which measures the subspace dispersion across the Brillouin zone. The maximally-localised Wannier functions within this subspace are obtained by subsequent minimisation of a functional that represents the total spread of the Wannier functions in real space. For the case of isolated energy bands only the second step of the procedure is required. Unusual features: Simple and user-friendly input system. Wannier functions and interpolated band structure output in a variety of file formats for visualisation. Running time: Test cases take 1 minute. References:N. Marzari, D. Vanderbilt, Maximally localized generalized Wannier functions for composite energy bands, Phys. Rev. B 56 (1997) 12847. I. Souza, N. Marzari, D. Vanderbilt, Maximally localized Wannier functions for entangled energy bands, Phys. Rev. B 65 (2001) 035109.

Spectroscopic ellipsometry and band structure of Si{sub 1{minus}y}C{sub y} alloys grown pseudomorphically on Si (001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zollner, S.; Herzinger, C.M.; Woollam, J.A.

1995-10-01

The authors have measured the dielectric functions of three Si{sub 1{minus}y}C{sub y} alloys layers (y {le} 1.4%) grown pseudomorphically on Si (001) substrates using molecular beam epitaxy at low temperatures. From the numerical derivatives of the measured spectra, they determine the critical point energies E{sub 0}{prime} and E{sub 1} as a function of y (y {le} 1.4%) using a comparison with analytical line shapes and analyze these energies in terms of the expected shifts and splittings due to negative hydrostatic pressure, shear stress, and alloying. Their data agree well with the calculated shifts for E{sub 1}, but the E{sub 0}{prime}more » energies are lower than expected. They discuss their results in comparison with recent tight-binding molecular dynamics simulations by Demkov and Sankey predicting a total breakdown of the virtual-crystal approximation for such alloys.« less

One-electron reduced density matrices of strongly correlated harmonium atoms.

PubMed

Cioslowski, Jerzy

2015-03-21

Explicit asymptotic expressions are derived for the reduced one-electron density matrices (the 1-matrices) of strongly correlated two- and three-electron harmonium atoms in the ground and first excited states. These expressions, which are valid at the limit of small confinement strength ω, yield electron densities and kinetic energies in agreement with the published values. In addition, they reveal the ω(5/6) asymptotic scaling of the exchange components of the electron-electron repulsion energies that differs from the ω(2/3) scaling of their Coulomb and correlation counterparts. The natural orbitals of the totally symmetric ground state of the two-electron harmonium atom are found to possess collective occupancies that follow a mixed power/Gaussian dependence on the angular momentum in variance with the simple power-law prediction of Hill's asymptotics. Providing rigorous constraints on energies as functionals of 1-matrices, these results are expected to facilitate development of approximate implementations of the density matrix functional theory and ensure their proper description of strongly correlated systems.

Loudness of steady sounds - A new theory

NASA Technical Reports Server (NTRS)

Howes, W. L.

1979-01-01

A new mathematical theory for calculating the loudness of steady sounds from power summation and frequency interaction, based on psychoacoustic and physiological information, assuems that loudness is a subjective measure of the electrical energy transmitted along the auditory nerve to the central nervous system. The auditory system consists of the mechanical part modeled by a bandpass filter with a transfer function dependent on the sound pressure, and the electrical part where the signal is transformed into a half-wave reproduction represented by the electrical power in impulsive discharges transmitted along neurons comprising the auditory nerve. In the electrical part the neurons are distributed among artificial parallel channels with frequency bandwidths equal to 'critical bandwidths for loudness', within which loudness is constant for constant sound pressure. The total energy transmitted to the central nervous system is the sum of the energy transmitted in all channels, and the loudness is proportional to the square root of the total filtered sound energy distributed over all channels. The theory explains many psychoacoustic phenomena such as audible beats resulting from closely spaced tones, interaction of sound stimuli which affect the same neurons affecting loudness, and of individually subliminal sounds becoming audible if they lie within the same critical band.

Density and energy relaxation in an open one-dimensional system

NASA Astrophysics Data System (ADS)

Jose, Prasanth P.; Bagchi, Biman

2004-05-01

A new master equation to mimic the dynamics of a collection of interacting random walkers in an open system is proposed and solved numerically. In this model, the random walkers interact through excluded volume interaction (single-file system); and the total number of walkers in the lattice can fluctuate because of exchange with a bath. In addition, the movement of the random walkers is biased by an external perturbation. Two models for the latter are considered: (1) an inverse potential (V∝1/r), where r is the distance between the center of the perturbation and the random walker and (2) an inverse of sixth power potential (V∝1/r6). The calculated density of the walkers and the total energy show interesting dynamics. When the size of the system is comparable to the range of the perturbing field, the energy relaxation is found to be highly nonexponential. In this range, the system can show stretched exponential (e-(t/τs)β) and even logarithmic time dependence of energy relaxation over a limited range of time. Introduction of density exchange in the lattice markedly weakens this nonexponentiality of the relaxation function, irrespective of the nature of perturbation.

Photoionization and photofragmentation of the C 60 + molecular ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baral, K. K.; Aryal, N. B.; Esteves-Macaluso, D. A.

2016-03-01

Cross-section measurements are reported for single and double photoionization of Cmore » $$+\\atop{60}$$ ions in the photon energy range 18-150 eV accompanied by the loss of zero to seven pairs of carbon atoms, as well as for fragmentation without ionization resulting in loss of two to eight pairs of C atoms in the photon energy range 18-65 eV. Absolute measurements were performed by merging a beam of C$$+\\atop{60}$$ molecular ions with a beam of monochromatized synchrotron radiation. Product channels involving dissociation yielding smaller fullerene fragment ions account for nearly half of the total measured oscillator strength in this energy range. The sum of cross sections for the measured product channels is compared to a published calculation of the total photoabsorption cross section of neutral C 60 based on time-dependent density-functional theory. Lastly, this comparison and an accounting of oscillator strengths indicate that with the exception of C$$+\\atop{58}$$, the most important product channels resulting from photoabsorption were accounted for in the experiment. Threshold energies for the successive removal of carbon atom pairs accompanying photoionization are also determined from the measurements.« less

Source-Free Exchange-Correlation Magnetic Fields in Density Functional Theory.

PubMed

Sharma, S; Gross, E K U; Sanna, A; Dewhurst, J K

2018-03-13

Spin-dependent exchange-correlation energy functionals in use today depend on the charge density and the magnetization density: E xc [ρ, m]. However, it is also correct to define the functional in terms of the curl of m for physical external fields: E xc [ρ,∇ × m]. The exchange-correlation magnetic field, B xc , then becomes source-free. We study this variation of the theory by uniquely removing the source term from local and generalized gradient approximations to the functional. By doing so, the total Kohn-Sham moments are improved for a wide range of materials for both functionals. Significantly, the moments for the pnictides are now in good agreement with experiment. This source-free method is simple to implement in all existing density functional theory codes.

Does Prop-2-ynylideneamine, HC≡CCH=NH, Exist in Space? A Theoretical and Computational Investigation

PubMed Central

Osman, Osman I.; Elroby, Shaaban A.; Aziz, Saadullah G.; Hilal, Rifaat H.

2014-01-01

MP2, DFT and CCSD methods with 6-311++G** and aug-cc-pvdz basis sets have been used to probe the structural changes and relative energies of E-prop-2-ynylideneamine (I), Z-prop-2-ynylideneamine (II), prop-1,2-diene-1-imine (III) and vinyl cyanide (IV). The energy near-equivalence and provenance of preference of isomers and tautomers were investigated by NBO calculations using HF and B3LYP methods with 6-311++G** and aug-cc-pvdz basis sets. All substrates have Cs symmetry. The optimized geometries were found to be mainly theoretical method dependent. All elected levels of theory have computed I/II total energy of isomerization (ΔE) of 1.707 to 3.707 kJ/mol in favour of II at 298.15 K. MP2 and CCSD methods have indicated clearly the preference of II over III; while the B3LYP functional predicted nearly similar total energies. All tested levels of theory yielded a global II/IV tautomerization total energy (ΔE) of 137.3–148.4 kJ/mol in support of IV at 298.15 K. The negative values of ΔS indicated that IV is favoured at low temperature. At high temperature, a reverse tautomerization becomes spontaneous and II is preferred. The existence of II in space was debated through the interpretation and analysis of the thermodynamic and kinetic studies of this tautomerization reaction and the presence of similar compounds in the Interstellar Medium (ISM). PMID:24950178

Maintenance of skeletal muscle energy homeostasis during prolonged wintertime fasting in the raccoon dog (Nyctereutes procyonoides).

PubMed

Kinnunen, Sanni; Mänttäri, Satu; Herzig, Karl-Heinz; Nieminen, Petteri; Mustonen, Anne-Mari; Saarela, Seppo

2015-05-01

The raccoon dog (Nyctereutes procyonoides) is a canid species with autumnal fattening and prolonged wintertime fasting. Nonpathological body weight cycling and the ability to tolerate food deficiency make this species a unique subject for studying physiological mechanisms in energy metabolism. AMP-activated protein kinase (AMPK) is a cellular energy sensor regulating energy homeostasis. During acute fasting, AMPK promotes fatty acid oxidation and enhances glucose uptake. We evaluated the effects of prolonged fasting on muscle energy metabolism in farm-bred raccoon dogs. Total and phosphorylated AMPK and acetyl-CoA carboxylase (ACC), glucose transporter 4 (GLUT 4), insulin receptor and protein kinase B (Akt) protein expressions of hind limb muscles were determined by Western blot after 10 weeks of fasting. Plasma insulin, leptin, ghrelin, glucose and free fatty acid levels were measured, and muscle myosin heavy chain (MHC) isoform composition analyzed. Fasting had no effects on AMPK phosphorylation, but total AMPK expression decreased in m. rectus femoris, m. tibialis anterior and m. extensor digitorum longus resulting in a higher phosphorylation ratio. Decreased total expression was also observed for ACC. Fasting did not influence GLUT 4, insulin receptor or Akt expression, but Akt phosphorylation was lower in m. flexor digitorum superficialis and m. extensor digitorum longus. Three MHC isoforms (I, IIa and IIx) were detected without differences in composition between the fasted and control animals. The studied muscles were resistant to prolonged fasting indicating that raccoon dogs have an effective molecular regulatory system for preserving skeletal muscle function during wintertime immobility and fasting.

Mechanical work and energy consumption in children with cerebral palsy after single-event multilevel surgery.

PubMed

Marconi, Valeria; Hachez, Hélèn; Renders, Anne; Docquier, Pierre-Louis; Detrembleur, Chrisitine

2014-09-01

Multilevel surgery is commonly performed to improve walking in children with cerebral palsy (CP). Classical gait analysis (kinetics, kinematics) demonstrated positive outcomes after this intervention, however it doesn't give global indication about gait's features. The assessment of energy cost and mechanical work of locomotion can provide an overall description of walking functionality. Therefore, we propose to describe the effects of multilevel surgery in children with CP, considering energetics, mechanical work, kinetic and kinematic of walking. We measured external, internal, total work, energy cost, recovery, efficiency, kinetic and kinematic of walking in 10 children with CP (4 girls, 6 boys; 13 years ± 2) before and 1 year after multilevel surgery. Kinetic and kinematic results are partially comparable to previous findings, energy cost of walking is significantly reduced (p < 0.05); external, internal, total work, recovery, efficiency are not significantly different (p = 0.129; p = 0.147; p = 0.795; p = 0.119; p = 0.21). The improvement of the walking's energy consumption is not accompanied by a corresponding improvement of mechanical work. Therefore it is conceivable that the improvement of walking economy depend on a reduced effort of the muscle to maintain the posture, rather then to an improvement of the mechanism of energy recovery typical of human locomotion. Copyright © 2014 Elsevier B.V. All rights reserved.

MM-ISMSA: An Ultrafast and Accurate Scoring Function for Protein-Protein Docking.

PubMed

Klett, Javier; Núñez-Salgado, Alfonso; Dos Santos, Helena G; Cortés-Cabrera, Álvaro; Perona, Almudena; Gil-Redondo, Rubén; Abia, David; Gago, Federico; Morreale, Antonio

2012-09-11

An ultrafast and accurate scoring function for protein-protein docking is presented. It includes (1) a molecular mechanics (MM) part based on a 12-6 Lennard-Jones potential; (2) an electrostatic component based on an implicit solvent model (ISM) with individual desolvation penalties for each partner in the protein-protein complex plus a hydrogen bonding term; and (3) a surface area (SA) contribution to account for the loss of water contacts upon protein-protein complex formation. The accuracy and performance of the scoring function, termed MM-ISMSA, have been assessed by (1) comparing the total binding energies, the electrostatic term, and its components (charge-charge and individual desolvation energies), as well as the per residue contributions, to results obtained with well-established methods such as APBSA or MM-PB(GB)SA for a set of 1242 decoy protein-protein complexes and (2) testing its ability to recognize the docking solution closest to the experimental structure as that providing the most favorable total binding energy. For this purpose, a test set consisting of 15 protein-protein complexes with known 3D structure mixed with 10 decoys for each complex was used. The correlation between the values afforded by MM-ISMSA and those from the other methods is quite remarkable (r(2) ∼ 0.9), and only 0.2-5.0 s (depending on the number of residues) are spent on a single calculation including an all vs all pairwise energy decomposition. On the other hand, MM-ISMSA correctly identifies the best docking solution as that closest to the experimental structure in 80% of the cases. Finally, MM-ISMSA can process molecular dynamics trajectories and reports the results as averaged values with their standard deviations. MM-ISMSA has been implemented as a plugin to the widely used molecular graphics program PyMOL, although it can also be executed in command-line mode. MM-ISMSA is distributed free of charge to nonprofit organizations.

Resonance electron attachment to plant hormones and its likely connection with biochemical processes

NASA Astrophysics Data System (ADS)

Pshenichnyuk, Stanislav A.; Modelli, Alberto

2014-01-01

Gas-phase formation of temporary negative ion states via resonance attachment of low-energy (0-6 eV) electrons into vacant molecular orbitals of salicylic acid (I) and its derivatives 3-hydroxy- (II) and 4-hydroxybenzoic acid (III), 5-cloro salicylic acid (IV) and methyl salicylate (V) was investigated for the first time by electron transmission spectroscopy. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies. Dissociative electron attachment spectroscopy (DEAS) was used to measure the fragment anion yields generated through dissociative decay channels of the parent molecular anions of compounds I-V, detected with a mass filter as a function of the incident electron energy in the 0-14 eV energy range. The most intense negative fragment produced by DEA to isomers I-III is the dehydrogenated molecular anion [M-H]-, mainly formed at incident electron energies around 1 eV. The vertical and adiabatic electron affinities were evaluated at the B3LYP/6-31+G(d) level as the anion/neutral total energy difference. The same theoretical method was also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo.

Local Fitting of the Kohn-Sham Density in a Gaussian and Plane Waves Scheme for Large-Scale Density Functional Theory Simulations.

PubMed

Golze, Dorothea; Iannuzzi, Marcella; Hutter, Jürg

2017-05-09

A local resolution-of-the-identity (LRI) approach is introduced in combination with the Gaussian and plane waves (GPW) scheme to enable large-scale Kohn-Sham density functional theory calculations. In GPW, the computational bottleneck is typically the description of the total charge density on real-space grids. Introducing the LRI approximation, the linear scaling of the GPW approach with respect to system size is retained, while the prefactor for the grid operations is reduced. The density fitting is an O(N) scaling process implemented by approximating the atomic pair densities by an expansion in one-center fit functions. The computational cost for the grid-based operations becomes negligible in LRIGPW. The self-consistent field iteration is up to 30 times faster for periodic systems dependent on the symmetry of the simulation cell and on the density of grid points. However, due to the overhead introduced by the local density fitting, single point calculations and complete molecular dynamics steps, including the calculation of the forces, are effectively accelerated by up to a factor of ∼10. The accuracy of LRIGPW is assessed for different systems and properties, showing that total energies, reaction energies, intramolecular and intermolecular structure parameters are well reproduced. LRIGPW yields also high quality results for extended condensed phase systems such as liquid water, ice XV, and molecular crystals.

Spectral representation of the three-body Coulomb problem. I. Nonautoionizing doubly excited states of high angular momentum in helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eiglsperger, Johannes; Piraux, Bernard; Madronero, Javier

2010-04-15

We investigate high-lying doubly excited nonautoionizing states of helium with total angular momentum L=1,2,...,9 with the help of a configuration interaction approach. We provide highly precise nonrelativistic energies of these states and discuss the properties of the wave functions with respect to the particle exchange operator.

Understanding the optical properties of ZnO1-xSx and ZnO1-xSex alloys

NASA Astrophysics Data System (ADS)

Baldissera, Gustavo; Persson, Clas

2016-01-01

ZnO1-xYx with chalcogen element Y exhibits intriguing optoelectronic properties as the alloying strongly impacts the band-gap energy Eg(x). In this work, we analyze and compare the electronic structures and the dielectric responses of Zn(O,S) and Zn(O,Se) alloys by means of the density functional theory and the partially self-consistent GW approach. We model the crystalline stability from the total energies, and the results indicate that Zn(O,S) is more stable as alloy than Zn(O,Se). We demonstrate also that ion relaxation strongly affects total energies, and that the band-gap bowing depends primarily on local relaxation of the bonds. Moreover, we show that the composition dependent band-gap needs to be analyzed by the band anti-crossing model for small alloying concentration, while the alloying band-bowing model is accurate for strong alloying. We find that the Se-based alloys have a stronger change in the band-gap energy (for instance, ΔEg(0.50) = Eg(ZnO) - Eg(x = 0.50) ≈ 2.2 eV) compared with that of the S-based alloy (ΔEg(0.50) = 1.2 eV), mainly due to a stronger relaxation of the Zn-anion bonds that affects the electronic structure near the band edges. The optical properties of the alloys are discussed in terms of the complex dielectric function ɛ(ω) = ɛ1(ω) + iɛ2(ω) and the absorption coefficient α(ω). While the large band-gap bowing directly impacts the low-energy absorption spectra, the high-frequency dielectric constant ɛ∞ is correlated to the intensity of the dielectric response at energies above 4 eV. Therefore, the dielectric constant is only weakly affected by the non-linear band-gap variation. Despite strong structural relaxation, the high absorption coefficients of the alloys demonstrate that the alloys have well-behaved optoelectronic properties.

Electron Emission from Amorphous Solid Water Induced by Passage of Energetic Protons and Fluorine Ions

PubMed Central

Toburen, L. H.; McLawhorn, S. L.; McLawhorn, R. A.; Carnes, K. D.; Dingfelder, M.; Shinpaugh, J. L.

2013-01-01

Absolute doubly differential electron emission yields were measured from thin films of amorphous solid water (ASW) after the transmission of 6 MeV protons and 19 MeV (1 MeV/nucleon) fluorine ions. The ASW films were frozen on thin (1-μm) copper foils cooled to approximately 50 K. Electrons emitted from the films were detected as a function of angle in both the forward and backward direction and as a function of the film thickness. Electron energies were determined by measuring the ejected electron time of flight, a technique that optimizes the accuracy of measuring low-energy electron yields, where the effects of molecular environment on electron transport are expected to be most evident. Relative electron emission yields were normalized to an absolute scale by comparison of the integrated total yields for proton-induced electron emission from the copper substrate to values published previously. The absolute doubly differential yields from ASW are presented along with integrated values, providing single differential and total electron emission yields. These data may provide benchmark tests of Monte Carlo track structure codes commonly used for assessing the effects of radiation quality on biological effectiveness. PMID:20681805

The Effects of Nonzero Total Electron Spin in the X˜3B1State of Methylene CH 2

NASA Astrophysics Data System (ADS)

Kozin, Igor N.; Jensen, Per

1997-06-01

We report here how we have incorporated the effects of a nonzero total electron spin in the MORBID Hamiltonian and computer program [P. Jensen,J. Mol. Spectrosc.128,478-501 (1988);J. Chem. Soc. Faraday Trans. 284,1315-1340 (1988);in"Methods in Computational Molecular Physics" (S. Wilson and G. H. F. Diercksen, Eds.), Plenum Press, New York, 1992] for calculating the rovibronic energies of a triatomic molecule directly from the potential energy function. The spin-spin and spin-rotation Hamiltonian terms, given in a form depending on the vibrational coordinates, have been expressed in terms of isotope-independent functions and added to the MORBID rotation-vibration Hamiltonian. The eigenvalues of the resulting Hamiltonian are obtained in a variational procedure. This method is tested on the methylene radical CH2in theX˜3B1electronic ground state for which we describe simultaneously the splittings due to electron spin for the isotopomers12CH2,12CD2, and13CH2. For these molecules, experimental data are available, and we compare the results of least-squares fits to these data with predictions fromab initiotheory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shulenburger, Luke; Baczewski, A. D.; Zhu, Z.

Sensitive dependence of the electronic structure on the number of layers in few-layer phosphorene raises a question about the true nature of the interlayer interaction in so-called van der Waals (vdW) solids . We performed quantum Monte Carlo calculations and found that the interlayer interaction in bulk black phosphorus and related few-layer phosphorene is associated with a significant charge redistribution that is incompatible with purely dispersive forces and not captured by density functional theory calculations with different vdW corrected functionals. Lastly, these findings confirm the necessity of more sophisticated treatment of nonlocal electron correlation in total energy calculations.

Energy from Redox Disproportionation of Sugar Carbon Drives Biotic and Abiotic Synthesis

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

1997-01-01

To identify the energy source that drives the biosynthesis of amino acids, lipids, and nucleotides from glucose, we calculated the free energy change due to redox disproportionation of the substrate carbon of: (1) 26-carbon fermentation reactions and (2) the biosynthesis of amino acids and lipids of E. coli from glucose. The free energy (cal/mmol of carbon) of these reactions was plotted as a function of the degree of redox disproportionation of carbon (disproportionative electron transfers (mmol)/mmol of carbon). The zero intercept and proportionality between energy yield and degree of redox disproportionation exhibited by this plot demonstrate that redox disproportionation is the principal energy source of these redox reactions (slope of linear fit = -10.4 cal/mmol of disproportionative electron transfers). The energy and disproportionation values of E. coli amino acid and lipid biosynthesis from glucose lie near this linear curve fit with redox disproportionation accounting for 84% and 96% (and ATP only 6% and 1 %) of the total energy of amino acid and lipid biosynthesis, respectively. These observations establish that redox disproportionation of carbon, and not ATP, is the primary energy source driving amino acid and lipid biosynthesis from glucose. In contrast, we found that nucteotide biosynthesis involves very little redox disproportionation, and consequently depends almost entirely on ATP for energy. The function of sugar redox disproportionation as the major source of free energy for the biosynthesis of amino acids and lipids suggests that sugar disproportionation played a central role in the origin of metabolism, and probably the origin of life.

Energy from Redox Disproportionation of Sugar Carbon Drives Biotic and Abiotic Synthesis

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

1997-01-01

To identify the energy source that drives the biosynthesis of amino acids, lipids, and nucleotides from glucose, we calculated the free energy change due to redox disproportionation of the substrate carbon of: (1) 26-carbon fermentation reactions and (2) the biosynthesis of amino acids and lipids of E. coli from glucose. The free energy (cal/mmol of carbon) of these reactions was plotted as a function of the degree of redox disproportionation of carbon (disproportionative electron transfers (mmol)/mmol of carbon). The zero intercept and proportionality between energy yield and degree of redox disproportionation exhibited by this plot demonstrate that redox disproportionation is the principal energy source of these redox reactions (slope of linear fit = -10.4 cal/mmol of disproportionative electron transfers). The energy and disproportionation values of E. coli amino acid and lipid biosynthesis from glucose lie near this linear curve fit with redox disproportionation accounting for 84% and 96% (and ATP only 6% and 1%) of the total energy of amino acid and lipid biosynthesis, respectively. These observations establish that redox disproportionation of carbon, and not ATP, is the primary energy source driving amino acid and lipid biosynthesis from glucose. In contrast, we found that nucleotide biosynthesis involves very little redox disproportionation, and consequently depends almost entirely on ATP for energy. The function of sugar redox disproportionation as the major source of free energy for the biosynthesis of amino acids and lipids suggests that sugar disproportionation played a central role in the origin of metabolism, and probably the origin of life.

Extending density functional embedding theory for covalently bonded systems.

PubMed

Yu, Kuang; Carter, Emily A

2017-12-19

Quantum embedding theory aims to provide an efficient solution to obtain accurate electronic energies for systems too large for full-scale, high-level quantum calculations. It adopts a hierarchical approach that divides the total system into a small embedded region and a larger environment, using different levels of theory to describe each part. Previously, we developed a density-based quantum embedding theory called density functional embedding theory (DFET), which achieved considerable success in metals and semiconductors. In this work, we extend DFET into a density-matrix-based nonlocal form, enabling DFET to study the stronger quantum couplings between covalently bonded subsystems. We name this theory density-matrix functional embedding theory (DMFET), and we demonstrate its performance in several test examples that resemble various real applications in both chemistry and biochemistry. DMFET gives excellent results in all cases tested thus far, including predicting isomerization energies, proton transfer energies, and highest occupied molecular orbital-lowest unoccupied molecular orbital gaps for local chromophores. Here, we show that DMFET systematically improves the quality of the results compared with the widely used state-of-the-art methods, such as the simple capped cluster model or the widely used ONIOM method.

Total Reaction Cross Section Excitation Function Studies for 6He Interaction with 181Ta, 59Co, natSi, 9Be Nuclei

NASA Astrophysics Data System (ADS)

Sobolev, Yu. G.; Penionzhkevich, Yu. E.; Borcea, C.; Demekhina, N. A.; Eshanov, A. G.; Ivanov, M. P.; Kabdrakhimova, G. D.; Kabyshev, A. M.; Kugler, A.; Kuterbekov, K. A.; Lukyanov, K. V.; Maj, A.; Maslov, V. A.; Negret, A.; Skobelev, N. K.; Testov, D.; Trzaska, W. H.; Voskobojnik, E. I.; Zemlyanaya, E. V.

2015-06-01

Total reaction cross section excitation functions σR(E) were measured for 6He secondary beam particles on 181Ta, 59Co, natSi and 9Be targets in a wide energy range by direct and model-independent method. This experimental method was based on prompt n-γ 4π-technique applied in event-by event mode. A high efficiency CsI(Tl) γ-spectrometer was used for the detection of reaction products (prompt γ-quanta and neutrons) accompanying each reaction event. Using the ACCULINNA fragment-separator 6He fragments (produced by 11B primary beam with 9Be target) are separated and transported to n-γ shielded experimental cave at FLNR JINR. The measured total reaction cross section data σR(E) for the above mentioned reactions are compared with a theoretical calculation based on the optical potential with the real part having the double-folding form.

The role of confined collagen geometry in decreasing nucleation energy barriers to intrafibrillar mineralization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros

Mineralization of collagen is critical for the mechanical functions of bones and teeth. Calcium phosphate nucleation in collagenous structures follows distinctly different patterns in highly confined gap regions (nanoscale confinement) than in less confined extrafibrillar spaces (microscale confinement). Although the mechanism(s) driving these differences are still largely unknown, differences in the free energy for nucleation may explain these two mineralization behaviors. Here, we report on experimentally obtained nucleation energy barriers to intra- and extrafibrillar mineralization, using in situ X-ray scattering observations and classical nucleation theory. Polyaspartic acid, an extrafibrillar nucleation inhibitor, increases interfacial energies between nuclei and mineralization fluids. Inmore » contrast, the confined gap spaces inside collagen fibrils lower the energy barrier by reducing the reactive surface area of nuclei, decreasing the surface energy penalty. The confined gap geometry, therefore, guides the two-dimensional morphology and structure of bioapatite and changes the nucleation pathway by reducing the total energy barrier.« less

The role of confined collagen geometry in decreasing nucleation energy barriers to intrafibrillar mineralization

DOE PAGES

Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros; ...

2018-03-06

Mineralization of collagen is critical for the mechanical functions of bones and teeth. Calcium phosphate nucleation in collagenous structures follows distinctly different patterns in highly confined gap regions (nanoscale confinement) than in less confined extrafibrillar spaces (microscale confinement). Although the mechanism(s) driving these differences are still largely unknown, differences in the free energy for nucleation may explain these two mineralization behaviors. Here, we report on experimentally obtained nucleation energy barriers to intra- and extrafibrillar mineralization, using in situ X-ray scattering observations and classical nucleation theory. Polyaspartic acid, an extrafibrillar nucleation inhibitor, increases interfacial energies between nuclei and mineralization fluids. Inmore » contrast, the confined gap spaces inside collagen fibrils lower the energy barrier by reducing the reactive surface area of nuclei, decreasing the surface energy penalty. The confined gap geometry, therefore, guides the two-dimensional morphology and structure of bioapatite and changes the nucleation pathway by reducing the total energy barrier.« less

Extending Measurements to En=30 MeV and Beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duke, Dana Lynn

The majority of energy release in the fission process is due to the kinetic energy of the fission fragments. Average Total Kinetic Energy measurements for the major actinides over a wide range of incident neutron energies were performed at LANSCE using a Frisch-gridded ionization chamber. The experiments and results of the 238U(n,f) and 235U(n,f) will be presented, including (En), (A), and mass yield distributions as a function of neutron energy. A preliminary (En) for 239Pu(n,f) will also be shown. The (En) shows a clear structure at multichance fission thresholds for all the reactions that we studied. The fragment masses aremore » determined using the iterative double energy (2E) method, with a resolution of A = 4 - 5 amu. The correction for the prompt fission neutrons is the main source of uncertainty, especially at high incident neutron energies, since the behavior of nubar(A,En) is largely unknown. Different correction methods will be discussed.« less

Misreporting of energy intake in the elderly using doubly labeled water to measure total energy expenditure and weight change.

PubMed

Shahar, Danit R; Yu, Binbing; Houston, Denise K; Kritchevsky, Stephen B; Newman, Anne B; Sellmeyer, Deborah E; Tylavsky, Frances A; Lee, Jung Sun; Harris, Tamara B

2010-02-01

One of the major problems in dietary assessment is inaccuracy in reporting diet. To examine the association between self-reported energy intake (EI) by food frequency questionnaire (FFQ) and energy expenditure (EE), measured by doubly labeled water (DLW), among older persons. EE was assessed in 298 high-functioning, community-dwelling older adults (70-79 years of age) over a 2-week period using DLW. Dietary intake was assessed using a Block FFQ. The ratio between reported EI and total energy expenditure (TEE) was calculated. Misreporting was defined as follows: participants with an EI/TEE ratio of <0.77 were categorized as low energy reporters, while participants with an EI/TEE ratio >1.28 were categorized as high energy reporters. Participants with an EI/TEE ratio of 0.77-1.28 were categorized as "true" energy reporters. One-year percent weight change prior to EE visit was used as another validation indicator. Participants who were low energy reporters but lost >2% of their body weight were categorized as undereaters. Two hundred ninety-six participants provided both FFQ and DLW measurements. Forty-three percent of participants were low energy reporters; among them, almost 30% lost weight and, therefore, were categorized as undereaters. The undereaters consumed significantly fewer calories. No difference in the frequency of low energy reporting was detected between genders or racial groups. Underreporters had significantly higher body weight than "true" or high reporters. Undereaters tended to have higher body mass index than the underreporters. Undereating is prevalent in the elderly and may be falsely perceived as underreporting. It should be further addressed and characterized in future studies.

Annual Performance of a Two-Speed, Dedicated Dehumidification Heat Pump in the NIST Net-Zero Energy Residential Test Facility

PubMed Central

Payne, W. Vance

2017-01-01

A 2715 ft2 (252 m2), two story, residential home of the style typical of the Gaithersburg, Maryland area was constructed in 2012 to demonstrate technologies for net-zero energy (NZE) homes (or ZEH). The NIST Net-Zero Energy Residential Test Facility (NZERTF) functions as a laboratory to support the development and adoption of cost-effective NZE designs, technologies, construction methods, and building codes. The primary design goal was to meet the comfort and functional needs of the simulated occupants. The first annual test period began on July 1, 2013 and ended June 30, 2014. During the first year of operation, the home's annual energy consumption was 13039 kWh (4.8 kWh ft-2, 51.7 kWh m-2), and the 10.2 kW solar photovoltaic system generated an excess of 484 kWh. During this period the heating and air conditioning of the home was performed by a novel air-source heat pump that utilized a reheat heat exchanger to allow hot compressor discharge gas to reheat the supply air during a dedicated dehumidification mode. During dedicated dehumidification, room temperature air was supplied to the living space until the relative humidity setpoint of 50% was satisfied. The heat pump consumed a total of 6225 kWh (2.3 kWh ft-2, 24.7 kWh m-2) of electrical energy for cooling, heating, and dehumidification. Annual cooling efficiency was 10.1 Btu W-1h-1 (2.95 W W-1), relative to the rated SEER of the heat pump of 15.8 Btu W-1h-1 (4.63 W W-1). Annual heating efficiency was 7.10 Btu W-1h-1 (2.09 W W-1), compared with the unit's rated HSPF of 9.05 Btu W-1h-1 (2.65 W W-1). These field measured efficiency numbers include dedicated dehumidification operation and standby energy use for the year. Annual sensible heat ratio was approximately 70%. Standby energy consumption was 5.2 % and 3.5 % of the total electrical energy used for cooling and heating, respectively. PMID:28729740

Annual Performance of a Two-Speed, Dedicated Dehumidification Heat Pump in the NIST Net-Zero Energy Residential Test Facility.

PubMed

Payne, W Vance

2016-01-01

A 2715 ft 2 (252 m 2 ), two story, residential home of the style typical of the Gaithersburg, Maryland area was constructed in 2012 to demonstrate technologies for net-zero energy (NZE) homes (or ZEH). The NIST Net-Zero Energy Residential Test Facility (NZERTF) functions as a laboratory to support the development and adoption of cost-effective NZE designs, technologies, construction methods, and building codes. The primary design goal was to meet the comfort and functional needs of the simulated occupants. The first annual test period began on July 1, 2013 and ended June 30, 2014. During the first year of operation, the home's annual energy consumption was 13039 kWh (4.8 kWh ft -2 , 51.7 kWh m -2 ), and the 10.2 kW solar photovoltaic system generated an excess of 484 kWh. During this period the heating and air conditioning of the home was performed by a novel air-source heat pump that utilized a reheat heat exchanger to allow hot compressor discharge gas to reheat the supply air during a dedicated dehumidification mode. During dedicated dehumidification, room temperature air was supplied to the living space until the relative humidity setpoint of 50% was satisfied. The heat pump consumed a total of 6225 kWh (2.3 kWh ft -2, 24.7 kWh m -2 ) of electrical energy for cooling, heating, and dehumidification. Annual cooling efficiency was 10.1 Btu W -1 h -1 (2.95 W W -1 ), relative to the rated SEER of the heat pump of 15.8 Btu W -1 h -1 (4.63 W W -1 ). Annual heating efficiency was 7.10 Btu W -1 h -1 (2.09 W W -1 ), compared with the unit's rated HSPF of 9.05 Btu W -1 h -1 (2.65 W W -1 ). These field measured efficiency numbers include dedicated dehumidification operation and standby energy use for the year. Annual sensible heat ratio was approximately 70%. Standby energy consumption was 5.2 % and 3.5 % of the total electrical energy used for cooling and heating, respectively.

0–0 Energies Using Hybrid Schemes: Benchmarks of TD-DFT, CIS(D), ADC(2), CC2, and BSE/GW formalisms for 80 Real-Life Compounds

PubMed Central

2015-01-01

The 0–0 energies of 80 medium and large molecules have been computed with a large panel of theoretical formalisms. We have used an approach computationally tractable for large molecules, that is, the structural and vibrational parameters are obtained with TD-DFT, the solvent effects are accounted for with the PCM model, whereas the total and transition energies have been determined with TD-DFT and with five wave function approaches accounting for contributions from double excitations, namely, CIS(D), ADC(2), CC2, SCS-CC2, and SOS-CC2, as well as Green’s function based BSE/GW approach. Atomic basis sets including diffuse functions have been systematically applied, and several variations of the PCM have been evaluated. Using solvent corrections obtained with corrected linear-response approach, we found that three schemes, namely, ADC(2), CC2, and BSE/GW allow one to reach a mean absolute deviation smaller than 0.15 eV compared to the measurements, the two former yielding slightly better correlation with experiments than the latter. CIS(D), SCS-CC2, and SOS-CC2 provide significantly larger deviations, though the latter approach delivers highly consistent transition energies. In addition, we show that (i) ADC(2) and CC2 values are extremely close to each other but for systems absorbing at low energies; (ii) the linear-response PCM scheme tends to overestimate solvation effects; and that (iii) the average impact of nonequilibrium correction on 0–0 energies is negligible. PMID:26574326

Gibbs Energy Modeling of Digenite and Adjacent Solid-State Phases

NASA Astrophysics Data System (ADS)

Waldner, Peter

2017-08-01

All sulfur potential and phase diagram data available in the literature for solid-state equilibria related to digenite have been assessed. Thorough thermodynamic analysis at 1 bar total pressure has been performed. A three-sublattice approach has been developed to model the Gibbs energy of digenite as a function of composition and temperature using the compound energy formalism. The Gibbs energies of the adjacent solid-state phases covelitte and high-temperature chalcocite are also modeled treating both sulfides as stoichiometric compounds. The novel model for digenite offers new interpretation of experimental data, may contribute from a thermodynamic point of view to the elucidation of the role of copper species within the crystal structure and allows extrapolation to composition regimes richer in copper than stoichiometric digenite Cu2S. Preliminary predictions into the ternary Cu-Fe-S system at 1273 K (1000 °C) using the Gibbs energy model of digenite for calculating its iron solubility are promising.

The vibrational spectroscopic studies and molecular property analysis of Estradiol, Tamoxifen and their interaction by density functional theory

NASA Astrophysics Data System (ADS)

Borah, Mukunda Madhab; Gomti Devi, Th.

2018-07-01

In the present work Tamoxifen, Estradiol and their interaction are studied using the experimental and theoretical methodologies. The spectral characterization was made by using Raman, FTIR, DFT and VEDA calculation. The optimization of the molecules have been studied using basis set B3LYP/6-31 G(d,p). Complete vibrational assignment of Tamoxifen, Estradiol and Estradiol + Tamoxifen have been attempted and the potential energy distribution and normal mode analysis had also been carried out to determine the contributions of bond oscillators in each normal mode. We have optimized several binding modes of Estradiol and Tamoxifen and taken the lowest energy conformer in our interest. The molecular geometry, HOMO-LUMO energy gap, molecular hardness (η), ionization energy (IE), electron affinity (EA), total energy and dipole moment were analyzed. The observed experimental and the scaled theoretical results were found in good agreement.

Apparent Endless Extraction of Energy from the Vacuum by Cyclic Manipulation of Casimir Cavity Dimensions

NASA Technical Reports Server (NTRS)

Forward, Robert L.

1999-01-01

In 1983, Ambjorn and Wolfram produced plots of the energy density of the quantum mechanical electromagnetic fluctuations in a volume of vacuum bounded by perfectly conducting walls in the shape of a rectangular cavity of dimensions a(1), a(2), and a(3), as a function of the ratios a(2)/a(1) and a(3)/a(1). Portions of these plots are double-valued, in that they allow rectangular cavities with the same, value of a(2)/a(1), but different values of a(3)/a(1), to have the saint total energy. Using these double-valued regions of the plots, I show that it is possible to define a "Casimir Vacuum Energy Extraction Cycle" which apparently would allow for the endless extraction of energy from the vacuum in the Casimir cavity by cyclic manipulation of the Casimir cavity dimensions.

Thin-shell wormholes in rainbow gravity

NASA Astrophysics Data System (ADS)

Amirabi, Z.; Halilsoy, M.; Mazharimousavi, S. Habib

2018-03-01

At the Planck scale of length ˜10‑35 m where the energy is comparable with the Planck energy, the quantum gravity corrections to the classical background spacetime results in gravity’s rainbow or rainbow gravity. In this modified theory of gravity, geometry depends on the energy of the test particle used to probe the spacetime, such that in the low energy limit, it yields the standard general relativity. In this work, we study the thin-shell wormholes in the spherically symmetric rainbow gravity. We find the corresponding properties in terms of the rainbow functions which are essential in the rainbow gravity and the stability of such thin-shell wormholes are investigated. Particularly, it will be shown that there are exact solutions in which high energy particles crossing the throat will encounter less amount of total exotic matter. This may be used as an advantage over general relativity to reduce the amount of exotic matter.

Intermediate photovoltaic system application experiment operational performance report: Volume 5, for Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-02-01

Performance data for the month of January, 1982 for a grid connected photovoltaic power supply in Massachusetts are presented. Data include: monthly and daily electrical energy produced; monthly and daily solar energy incident on the array; monthly and daily array efficiency; plots of energy produced as a function of power level, voltage, cell temperature and time of day; power conditioner input, output and efficiency for each of two individual units and for the total power conditioning system; photovoltaic system efficiency; capacity factor; PV system to load and grid to load energies and corresponding dollar values; daily energy supplies to the load by the PV system; daily PV system availability; monthly and hourly insolation; monthly and hourly temperature average; monthly and hourly wind speed; wind direction distribution; average heating and cooling degree days; number of freeze/thaw cycles; and the data acquisition mode and recording interval plot.

A harmonic adiabatic approximation to calculate highly excited vibrational levels of ``floppy molecules''

NASA Astrophysics Data System (ADS)

Lauvergnat, David; Nauts, André; Justum, Yves; Chapuisat, Xavier

2001-04-01

The harmonic adiabatic approximation (HADA), an efficient and accurate quantum method to calculate highly excited vibrational levels of molecular systems, is presented. It is well-suited to applications to "floppy molecules" with a rather large number of atoms (N>3). A clever choice of internal coordinates naturally suggests their separation into active, slow, or large amplitude coordinates q', and inactive, fast, or small amplitude coordinates q″, which leads to an adiabatic (or Born-Oppenheimer-type) approximation (ADA), i.e., the total wave function is expressed as a product of active and inactive total wave functions. However, within the framework of the ADA, potential energy data concerning the inactive coordinates q″ are required. To reduce this need, a minimum energy domain (MED) is defined by minimizing the potential energy surface (PES) for each value of the active variables q', and a quadratic or harmonic expansion of the PES, based on the MED, is used (MED harmonic potential). In other words, the overall picture is that of a harmonic valley about the MED. In the case of only one active variable, we have a minimum energy path (MEP) and a MEP harmonic potential. The combination of the MED harmonic potential and the adiabatic approximation (harmonic adiabatic approximation: HADA) greatly reduces the size of the numerical computations, so that rather large molecules can be studied. In the present article however, the HADA is applied to our benchmark molecule HCN/CNH, to test the validity of the method. Thus, the HADA vibrational energy levels are compared and are in excellent agreement with the ADA calculations (adiabatic approximation with the full PES) of Light and Bačić [J. Chem. Phys. 87, 4008 (1987)]. Furthermore, the exact harmonic results (exact calculations without the adiabatic approximation but with the MEP harmonic potential) are compared to the exact calculations (without any sort of approximation). In addition, we compare the densities of the bending motion during the HCN/CNH isomerization, computed with the HADA and the exact wave function.

Reliable energy level alignment at physisorbed molecule-metal interfaces from density functional theory.

PubMed

Egger, David A; Liu, Zhen-Fei; Neaton, Jeffrey B; Kronik, Leeor

2015-04-08

A key quantity for molecule-metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal-molecule interfaces. The method builds on the "DFT+Σ" approach, grounded in many-body perturbation theory, which introduces an approximate electron self-energy that corrects the level alignment obtained from conventional DFT for missing exchange and correlation effects associated with the gas-phase molecule and substrate polarization. Here, we extend the DFT+Σ approach in two important ways: first, we employ optimally tuned range-separated hybrid functionals to compute the gas-phase term, rather than rely on GW or total energy differences as in prior work; second, we use a nonclassical DFT-determined image-charge plane of the metallic surface to compute the substrate polarization term, rather than the classical DFT-derived image plane used previously. We validate this new approach by a detailed comparison with experimental and theoretical reference data for several prototypical molecule-metal interfaces, where excellent agreement with experiment is achieved: benzene on graphite (0001), and 1,4-benzenediamine, Cu-phthalocyanine, and 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111). In particular, we show that the method correctly captures level alignment trends across chemical systems and that it retains its accuracy even for molecules for which conventional DFT suffers from severe self-interaction errors.

Reliable Energy Level Alignment at Physisorbed Molecule–Metal Interfaces from Density Functional Theory

PubMed Central

2015-01-01

A key quantity for molecule–metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal–molecule interfaces. The method builds on the “DFT+Σ” approach, grounded in many-body perturbation theory, which introduces an approximate electron self-energy that corrects the level alignment obtained from conventional DFT for missing exchange and correlation effects associated with the gas-phase molecule and substrate polarization. Here, we extend the DFT+Σ approach in two important ways: first, we employ optimally tuned range-separated hybrid functionals to compute the gas-phase term, rather than rely on GW or total energy differences as in prior work; second, we use a nonclassical DFT-determined image-charge plane of the metallic surface to compute the substrate polarization term, rather than the classical DFT-derived image plane used previously. We validate this new approach by a detailed comparison with experimental and theoretical reference data for several prototypical molecule–metal interfaces, where excellent agreement with experiment is achieved: benzene on graphite (0001), and 1,4-benzenediamine, Cu-phthalocyanine, and 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111). In particular, we show that the method correctly captures level alignment trends across chemical systems and that it retains its accuracy even for molecules for which conventional DFT suffers from severe self-interaction errors. PMID:25741626

Theoretical study of the design dye-sensitivity for usage in the solar cell device

NASA Astrophysics Data System (ADS)

Alrikabi, Alaa

There are many applications in the polymer chemistry, pharmaceutical, agricultural and industrial fields of the thiadiazole molecule and their derivatives. Allowance of the energy gap of the polymer conjugated is an object of great interesting debit for the possible removal of a doping in the preparation of highly conductivity polymers. Thiadiazoles derivatives are structural foundation of the polymer materials. In this present work, the electronic properties of graphene nanoflakes (GNFs)-phenanthrene-1,3,4-thiadiazoles oligomers are studied and discussed. Where thiadiazoles is expanded from one to 9 unit's molecules at the structure. The energy gap, HOMO, LUMO distribution, total energy, Fermi level energy, work function, maximum wavelength absorption, vertical absorption energies, and oscillator strengths are calculated for each molecule. All calculations are carry out by usage density function theory (DFT) and depended time density function theory (TD-DFT) with the B3LYP/6-31G model in the Gaussian 09W software packages. Results show that increasing the number of monomeric units lead to great enhance in the electronic properties, which caused it decreased the band gap from 3.17 eV in the system with one unit of thiadiazole just to 1.35 eV in the system with 9 units of thiadiazole. This case is raised the value of maximum absorption wavelengths to >500 nm to give the better performance in optoelectronic and solar cell, as these structures have prime absorption bands within the solar spectrum.

Centrality and energy dependence of charged-particle multiplicities in heavy ion collisions in the context of elementary reactions

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G. J. Van; Verdier, R.; Veres, G. I.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

2006-08-01

The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at sNN= 19.6, 130, and 200 GeV. An approximate independence of / on the number of participating nucleons is observed, reminiscent of “wounded nucleon” scaling (Nch∝Npart) observed in proton-nucleus collisions. Unlike p+A, the constant of proportionality does not seem to be set by the pp/p¯p data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in e+e- annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that e+e- and A+A data agree over a large range of center-of-mass energies (s>20 GeV), and pp/p¯p data can be brought to agree approximately with the e+e- data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between A+A and p+p collisions is the multiple collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles.

Amount of smoking, pulmonary function, and bone mineral density in middle-aged Korean men: KNHANES 2008-2011.

PubMed

Lee, Ji Hyun; Hong, A Ram; Kim, Jung Hee; Kim, Kyoung Min; Koo, Bo Kyung; Shin, Chan Soo; Kim, Sang Wan

2018-01-01

Smoking induces bone loss; however, data on the relationship between smoking history and bone mineral density (BMD) are lacking. Age and pulmonary function can affect BMD. We investigated the relationships among pack-years (PYs) of smoking, pulmonary function, and BMD in middle-aged Korean men (50-64 years old). This cross-sectional study used data from the Korean National Health and Nutrition Examination Survey, 2008-2011. All participants underwent BMD measurements using dual energy X-ray absorptiometry and pulmonary function tests using standardized spirometry. In total, 388 never-smokers and 1088 ever-smokers were analyzed. The number of PYs of smoking was negatively correlated with total hip BMD (r = -0.088; P = 0.004) after adjusting for age, height, and weight. Ever-smokers were classified into 3 groups according to PYs of smoking. The highest tertile (n = 482) exhibited significantly lower total hip bone mass than the lowest tertile (n = 214) after adjusting for confounding factors (age, height, weight, forced expiratory volume in 1 s (FEV 1 ), alcohol consumption, physical activity, and vitamin D levels) that could affect bone metabolism (P = 0.003). In conclusion, smoking for >30 PYs was significantly associated with low hip BMD after adjusting for pulmonary function in middle-aged Korean men. Long-term smoking may be a risk factor for bone loss in middle-aged men independent of age, height, weight, and pulmonary function.

Monitoring My Multiple Sclerosis

PubMed Central

Namey, Marie; Halper, June

2011-01-01

Optimal health of people with multiple sclerosis (MS) can be promoted by patients' sharing of health information gained through periodic self-monitoring with their health-care providers. The purpose of this study was to develop a valid and reliable self-administered scale to obtain information about MS patients' health status and the impact of the disease on their daily lives. We named this scale “Monitoring My Multiple Sclerosis” (MMMS). A cross-sectional survey was conducted of 171 MS patients who completed the MMMS and Patient-Determined Disease Steps (PDDS) scales and provided information on their MS disease classification and demographic characteristics. Data analysis included several parametric procedures. Factor analysis of the 26-item MMMS resulted in four factors with satisfactory α reliability coefficients for the total scale (0.90) and factored subscales: Physical (0.85), Relationships (0.80), Energy (0.70), and Cognitive/Mental (0.67). Analysis of variance demonstrated that the total scale and the Physical subscale, but not the Relationships subscale, showed significantly worse functioning for patients with either moderate or severe disability as measured by the PDDS than for patients with mild disability (P < .001). The Cognitive/Mental subscale showed significantly worse functioning for patients with moderate disability than for patients with mild disability (P < .05). However, the Energy subscale showed significantly worse functioning among moderately disabled patients than among severely disabled patients (P < .01). Independent t tests demonstrated that patients classified as having secondary progressive multiple sclerosis had significantly worse scores on the total MMMS (P < .05) and the Physical subscale (P < .001) than those classified as having relapsing-remitting multiple sclerosis. The MMMS demonstrated satisfactory reliability and validity and is recommended for use by MS patients and their health-care providers as a mechanism to promote the sharing of health information, to the benefit of both patients and providers. PMID:24453717

Performance of the density matrix functional theory in the quantum theory of atoms in molecules.

PubMed

García-Revilla, Marco; Francisco, E; Costales, A; Martín Pendás, A

2012-02-02

The generalization to arbitrary molecular geometries of the energetic partitioning provided by the atomic virial theorem of the quantum theory of atoms in molecules (QTAIM) leads to an exact and chemically intuitive energy partitioning scheme, the interacting quantum atoms (IQA) approach, that depends on the availability of second-order reduced density matrices (2-RDMs). This work explores the performance of this approach in particular and of the QTAIM in general with approximate 2-RDMs obtained from the density matrix functional theory (DMFT), which rests on the natural expansion (natural orbitals and their corresponding occupation numbers) of the first-order reduced density matrix (1-RDM). A number of these functionals have been implemented in the promolden code and used to perform QTAIM and IQA analyses on several representative molecules and model chemical reactions. Total energies, covalent intra- and interbasin exchange-correlation interactions, as well as localization and delocalization indices have been determined with these functionals from 1-RDMs obtained at different levels of theory. Results are compared to the values computed from the exact 2-RDMs, whenever possible.

Relationship between dynapenia and cardiorespiratory functions in healthy postmenopausal women: novel clinical criteria.

PubMed

Barbat-Artigas, Seébastien; Dupontgand, Sophie; Fex, Annie; Karelis, Antony D; Aubertin-Leheudre, Mylène

2011-04-01

Muscle strength seems to be a better indicator of physical limitations than skeletal muscle mass is. The purpose of this study was to investigate, using a new developed clinical tool, the relationship between type I dynapenia and cardiorespiratory functions in postmenopausal women. Forty-six postmenopausal women were recruited and divided into two groups (dynapenic vs nondynapenic). Body composition (bioelectrical impedancemetry), muscle strength (dynamometer), cardiorespiratory functions (maximum oxygen consumption and forced expiratory volume in 1 second), resting energy expenditure (indirect calorimetry), and dietary intake (3-d dietary journal) were measured. Type I dynapenia was defined as less than 1.53 kg per skeletal muscle mass (kg) based on handgrip dynamometer. Significant differences were found between dynapenic (n=23) and nondynapenic (n=23) postmenopausal women for cardiorespiratory functions (maximum oxygen consumption, P=0.003; and forced expiratory volume in 1 second, P=0.046). We observed no differences between groups for age, age at menopause, use of hormone therapy, body mass index, waist circumference, fat mass, resting energy expenditure, and total energy intake, which are known to be potential confounders. No differences were observed for cardiorespiratory functions when our population was divided into sarcopenic and nonsarcopenic groups. Type I dynapenic women have significantly poorer cardiorespiratory functions that do nondynapenic women even if they presented the same skeletal muscle mass index. Thus, based on our results, dynapenia could potentially be used as a marker of cardiorespiratory functions. The clinical method developed to identify dynapenic women could be used by health professionals. © 2011 by The North American Menopause Society

Coarse-grained density functional theories for metallic alloys: Generalized coherent-potential approximations and charge-excess functional theory

NASA Astrophysics Data System (ADS)

Bruno, Ezio; Mammano, Francesco; Fiorino, Antonino; Morabito, Emanuela V.

2008-04-01

The class of the generalized coherent-potential approximations (GCPAs) to the density functional theory (DFT) is introduced within the multiple scattering theory formalism with the aim of dealing with ordered or disordered metallic alloys. All GCPA theories are based on a common ansatz for the kinetic part of the Hohenberg-Kohn functional and each theory of the class is specified by an external model concerning the potential reconstruction. Most existing DFT implementations of CPA-based theories belong to the GCPA class. The analysis of the formal properties of the density functional defined by GCPA theories shows that it consists of marginally coupled local contributions. Furthermore, it is shown that the GCPA functional does not depend on the details of the charge density and that it can be exactly rewritten as a function of the appropriate charge multipole moments to be associated with each lattice site. A general procedure based on the integration of the qV laws is described that allows for the explicit construction of the same function. The coarse-grained nature of the GCPA density functional implies a great deal of computational advantages and is connected with the O(N) scalability of GCPA algorithms. Moreover, it is shown that a convenient truncated series expansion of the GCPA functional leads to the charge-excess functional (CEF) theory [E. Bruno , Phys. Rev. Lett. 91, 166401 (2003)], which here is offered in a generalized version that includes multipolar interactions. CEF and the GCPA numerical results are compared with status of art linearized augmented plane wave (LAPW) full-potential density functional calculations for 62 bcc- and fcc-based ordered CuZn alloys, in all the range of concentrations. Two facts clearly emerge from these extensive tests. In the first place, the discrepancies between GCPA and CEF results are always within the numerical accuracy of the calculations, both for the site charges and the total energies. In the second place, the GCPA (or the CEF) is able to very carefully reproduce the LAPW site charges and a good agreement is obtained also about the total energies.

Carbon Dioxide Emissions From Fossil-Fuel Consumption in Indonesia

NASA Astrophysics Data System (ADS)

Gregg, J. S.; Robert, A. J.

2005-05-01

Applying monthly sales and consumption data of coal, petroleum and natural gas, a monthly time series of carbon dioxide emissions from fossil-fuel consumption is created for Indonesia. These are then modeled with an autoregressive function to produce a quantitative description of the seasonal distribution and long-term pattern of CO2 emissions. Currently, Indonesia holds the 21st ranked position in total anthropogenic CO2 emissions among countries of the world. The demand for energy in Indonesia has been growing rapidly in recent years as Indonesia attempts to modernize and upgrade the standard of living for its citizens. With such a large population (a quarter of a billion people), the recent increase observed in the per capita energy use equates to a large escalation in total CO2 emissions. However, the economy and political climate is rather turbulent and thus emissions tend to fluctuate wildly. For example, Indonesia's energy consumption dropped substantially during the Asian economic crisis in the late 1990s. It is likely that the recent tsunami will also significantly impact energy consumption as the hard-hit Aceh region is the largest fuel-producing region of Indonesia. Therefore, Indonesia is a country whose emissions are more unpredictable than most countries that emit comparable levels of CO2. Complicating matters further, data collection practices in Indonesia are less diligent than in other countries with more stable economies. Thus, though CO2 emissions from Indonesia are a particular challenge to model, they are an important component to understanding the total global carbon cycle.

Validity of virial theorem in all-electron mixed basis density functional, Hartree–Fock, and GW calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuwahara, Riichi; Accelrys K. K., Kasumigaseki Tokyu Building 17F, 3-7-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-0013; Tadokoro, Yoichi

In this paper, we calculate kinetic and potential energy contributions to the electronic ground-state total energy of several isolated atoms (He, Be, Ne, Mg, Ar, and Ca) by using the local density approximation (LDA) in density functional theory, the Hartree–Fock approximation (HFA), and the self-consistent GW approximation (GWA). To this end, we have implemented self-consistent HFA and GWA routines in our all-electron mixed basis code, TOMBO. We confirm that virial theorem is fairly well satisfied in all of these approximations, although the resulting eigenvalue of the highest occupied molecular orbital level, i.e., the negative of the ionization potential, is inmore » excellent agreement only in the case of the GWA. We find that the wave function of the lowest unoccupied molecular orbital level of noble gas atoms is a resonating virtual bound state, and that of the GWA spreads wider than that of the LDA and thinner than that of the HFA.« less

Molecular structure and vibrational spectroscopic studies of prothionamide by density functional theory

NASA Astrophysics Data System (ADS)

Yilmaz, A.; Bolukbasi, O.

2016-01-01

Prothionamide (PTH) is the secondary drug used against Mycobacterium tuberculosis bacteria and leprosy. The aim of this work was to investigate the potential energy surface map, anharmonic and harmonic vibrational spectra, NBO analysis and ELF (Electron Localization Function) of the title compound using DFT approach with the B3LYP (Becke, three-parameter, Lee-Yang-Parr) exchange-correlation functional with the 6-31G++(d, p) and the Z3POLX basis sets were employed. In the experimental part of this study, FT-Mid IR, FT-Far IR and FT-Raman spectra of the molecule were recorded in the regions 4000-450 cm-1, 700-30 cm-1 and 4000-100 cm-1 respectively in the solid phase. The comparison between calculated and experimental vibrational spectra (infrared and Raman spectra) and assignments of fundamental vibrational modes were characterized by total energy distribution (TED). Theoretical spectra were seen to be in good agreement with those of the experimental ones.

Creation of energetic biothermite inks using ferritin liquid protein

NASA Astrophysics Data System (ADS)

Slocik, Joseph M.; McKenzie, Ruel; Dennis, Patrick B.; Naik, Rajesh R.

2017-04-01

Energetic liquids function mainly as fuels due to low energy densities and slow combustion kinetics. Consequently, these properties can be significantly increased through the addition of metal nanomaterials such as aluminium. Unfortunately, nanoparticle additives are restricted to low mass fractions in liquids because of increased viscosities and severe particle agglomeration. Nanoscale protein ionic liquids represent multifunctional solvent systems that are well suited to overcoming low mass fractions of nanoparticles, producing stable nanoparticle dispersions and simultaneously offering a source of oxidizing agents for combustion of reactive nanomaterials. Here, we use iron oxide-loaded ferritin proteins to create a stable and highly energetic liquid composed of aluminium nanoparticles and ferritin proteins for printing and forming 3D shapes and structures. In total, this bioenergetic liquid exhibits increased energy output and performance, enhanced dispersion and oxidation stability, lower activation temperatures, and greater processability and functionality.

Fast-ion distributions from third harmonic ICRF heating studied with neutron emission spectroscopy

NASA Astrophysics Data System (ADS)

Hellesen, C.; Gatu Johnson, M.; Andersson Sundén, E.; Conroy, S.; Ericsson, G.; Eriksson, J.; Sjöstrand, H.; Weiszflog, M.; Johnson, T.; Gorini, G.; Nocente, M.; Tardocchi, M.; Kiptily, V. G.; Pinches, S. D.; Sharapov, S. E.; EFDA Contributors, JET

2013-11-01

The fast-ion distribution from third harmonic ion cyclotron resonance frequency (ICRF) heating on the Joint European Torus is studied using neutron emission spectroscopy with the time-of-flight spectrometer TOFOR. The energy dependence of the fast deuteron distribution function is inferred from the measured spectrum of neutrons born in DD fusion reactions, and the inferred distribution is compared with theoretical models for ICRF heating. Good agreements between modelling and measurements are seen with clear features in the fast-ion distribution function, that are due to the finite Larmor radius of the resonating ions, replicated. Strong synergetic effects between ICRF and neutral beam injection heating were also seen. The total energy content of the fast-ion population derived from TOFOR data was in good agreement with magnetic measurements for values below 350 kJ.

Algorithm based on the Thomson problem for determination of equilibrium structures of metal nanoclusters

NASA Astrophysics Data System (ADS)

Arias, E.; Florez, E.; Pérez-Torres, J. F.

2017-06-01

A new algorithm for the determination of equilibrium structures suitable for metal nanoclusters is proposed. The algorithm performs a stochastic search of the minima associated with the nuclear potential energy function restricted to a sphere (similar to the Thomson problem), in order to guess configurations of the nuclear positions. Subsequently, the guessed configurations are further optimized driven by the total energy function using the conventional gradient descent method. This methodology is equivalent to using the valence shell electron pair repulsion model in guessing initial configurations in the traditional molecular quantum chemistry. The framework is illustrated in several clusters of increasing complexity: Cu7, Cu9, and Cu11 as benchmark systems, and Cu38 and Ni9 as novel systems. New equilibrium structures for Cu9, Cu11, Cu38, and Ni9 are reported.

Algorithm based on the Thomson problem for determination of equilibrium structures of metal nanoclusters.

PubMed

Arias, E; Florez, E; Pérez-Torres, J F

2017-06-28

A new algorithm for the determination of equilibrium structures suitable for metal nanoclusters is proposed. The algorithm performs a stochastic search of the minima associated with the nuclear potential energy function restricted to a sphere (similar to the Thomson problem), in order to guess configurations of the nuclear positions. Subsequently, the guessed configurations are further optimized driven by the total energy function using the conventional gradient descent method. This methodology is equivalent to using the valence shell electron pair repulsion model in guessing initial configurations in the traditional molecular quantum chemistry. The framework is illustrated in several clusters of increasing complexity: Cu 7 , Cu 9 , and Cu 11 as benchmark systems, and Cu 38 and Ni 9 as novel systems. New equilibrium structures for Cu 9 , Cu 11 , Cu 38 , and Ni 9 are reported.

Measurements of Excitation Functions and Line Polarizations for Electron Impact Excitation of the n = 2, 3 States of Atomic Hydrogen in the Energy Range 11 - 2000 eV

NASA Technical Reports Server (NTRS)

James, G. K.; Ajello, J. M.; Kanik, I.; Slevin, J.; Franklin, B.; Shemansky, D.

1993-01-01

The electron-atomic hydrogen scattering system is an important testing ground for theoretical models and has received a great deal of attention from experimentalists and theoreticians alike over the years. A complete description of the excitation process requires a knowledge of many different parameters, and experimental measurements of these parameters have been performed in various laboratories around the world. As far as total cross section data are concerned it has been noted that the discrepancy between the data of Long et al. and Williams for n = 2 excitations needs to be resolved in the interests of any further refinement of theory. We report new measurements of total cross sections and atomic line polarizations for both n=2 and n=3 excitations at energies from threshold to 2000 eV...

Efficient and accurate treatment of electron correlations with correlation matrix renormalization theory

DOE PAGES

Yao, Y. X.; Liu, J.; Liu, C.; ...

2015-08-28

We present an efficient method for calculating the electronic structure and total energy of strongly correlated electron systems. The method extends the traditional Gutzwiller approximation for one-particle operators to the evaluation of the expectation values of two particle operators in the many-electron Hamiltonian. The method is free of adjustable Coulomb parameters, and has no double counting issues in the calculation of total energy, and has the correct atomic limit. We demonstrate that the method describes well the bonding and dissociation behaviors of the hydrogen and nitrogen clusters, as well as the ammonia composed of hydrogen and nitrogen atoms. We alsomore » show that the method can satisfactorily tackle great challenging problems faced by the density functional theory recently discussed in the literature. The computational workload of our method is similar to the Hartree-Fock approach while the results are comparable to high-level quantum chemistry calculations.« less

a New Set-Up for Total Reaction Cross Section Measuring

NASA Astrophysics Data System (ADS)

Sobolev, Yu. G.; Ivanov, M. P.; Kugler, A.; Penionzhkevich, Yu. E.

2013-06-01

The experimental method and set-up based on 4 n-Υ-technique for direct and modelindependent measuring of the total reaction cross section σR have been presented. The excitation function σR(E) for 6He+197Au reaction at the Coulomb barrier energy region has been measured. The measured data are compared with the summarized cross section which has been prepared by summing of measured cross sections of main reaction channels: 1n-transfer and 197Au(6He, xn)203-xnT1 with x = 2÷7 evaporation reaction channels.

Statistical properties of kinetic and total energy densities in reverberant spaces.

PubMed

Jacobsen, Finn; Molares, Alfonso Rodríguez

2010-04-01

Many acoustical measurements, e.g., measurement of sound power and transmission loss, rely on determining the total sound energy in a reverberation room. The total energy is usually approximated by measuring the mean-square pressure (i.e., the potential energy density) at a number of discrete positions. The idea of measuring the total energy density instead of the potential energy density on the assumption that the former quantity varies less with position than the latter goes back to the 1930s. However, the phenomenon was not analyzed until the late 1970s and then only for the region of high modal overlap, and this analysis has never been published. Moreover, until fairly recently, measurement of the total sound energy density required an elaborate experimental arrangement based on finite-difference approximations using at least four amplitude and phase matched pressure microphones. With the advent of a three-dimensional particle velocity transducer, it has become somewhat easier to measure total rather than only potential energy density in a sound field. This paper examines the ensemble statistics of kinetic and total sound energy densities in reverberant enclosures theoretically, experimentally, and numerically.

Studying the varied shapes of gold clusters by an elegant optimization algorithm that hybridizes the density functional tight-binding theory and the density functional theory

NASA Astrophysics Data System (ADS)

Yen, Tsung-Wen; Lim, Thong-Leng; Yoon, Tiem-Leong; Lai, S. K.

2017-11-01

We combined a new parametrized density functional tight-binding (DFTB) theory (Fihey et al. 2015) with an unbiased modified basin hopping (MBH) optimization algorithm (Yen and Lai 2015) and applied it to calculate the lowest energy structures of Au clusters. From the calculated topologies and their conformational changes, we find that this DFTB/MBH method is a necessary procedure for a systematic study of the structural development of Au clusters but is somewhat insufficient for a quantitative study. As a result, we propose an extended hybridized algorithm. This improved algorithm proceeds in two steps. In the first step, the DFTB theory is employed to calculate the total energy of the cluster and this step (through running DFTB/MBH optimization for given Monte-Carlo steps) is meant to efficiently bring the Au cluster near to the region of the lowest energy minimum since the cluster as a whole has explicitly considered the interactions of valence electrons with ions, albeit semi-quantitatively. Then, in the second succeeding step, the energy-minimum searching process will continue with a skilledly replacement of the energy function calculated by the DFTB theory in the first step by one calculated in the full density functional theory (DFT). In these subsequent calculations, we couple the DFT energy also with the MBH strategy and proceed with the DFT/MBH optimization until the lowest energy value is found. We checked that this extended hybridized algorithm successfully predicts the twisted pyramidal structure for the Au40 cluster and correctly confirms also the linear shape of C8 which our previous DFTB/MBH method failed to do so. Perhaps more remarkable is the topological growth of Aun: it changes from a planar (n =3-11) → an oblate-like cage (n =12-15) → a hollow-shape cage (n =16-18) and finally a pyramidal-like cage (n =19, 20). These varied forms of the cluster's shapes are consistent with those reported in the literature.

Evolution of the orbitals Dy-4f in the DyB2 compound using the LDA, PBE approximations, and the PBE0 hybrid functional

NASA Astrophysics Data System (ADS)

Rasero Causil, Diego; Ortega López, César; Espitia Rico, Miguel

2018-04-01

Computational calculations of total energy based on density functional theory were used to investigate the structural, electronic, and magnetic properties of the DyB2 compounds in the hexagonal structure. The calculations were carried out by means of the full-potential linearized augmented plane wave (FP-LAPW) method, employing the computational Wien2k package. The local density approximation (LDA) and the generalized gradient approximation (GGA) were used for the electron-electron interactions. Additionally, we used the functional hybrid PBE0 for a better description the electronic and magnetic properties, because the DyB2 compound is a strongly-correlated system. We found that the calculated lattice constant agrees well with the values reported theoretically and experimentally. The density of states (DOS) calculation shows that the compound exhibits a metallic behavior and has magnetic properties, with a total magnetic moment of 5.47 μ0/cell determined mainly by the 4f states of the rare earth elements. The functional PBE0 shows a strong localization of the Dy-4f orbitals.

Fluctuating observation time ensembles in the thermodynamics of trajectories

NASA Astrophysics Data System (ADS)

Budini, Adrián A.; Turner, Robert M.; Garrahan, Juan P.

2014-03-01

The dynamics of stochastic systems, both classical and quantum, can be studied by analysing the statistical properties of dynamical trajectories. The properties of ensembles of such trajectories for long, but fixed, times are described by large-deviation (LD) rate functions. These LD functions play the role of dynamical free energies: they are cumulant generating functions for time-integrated observables, and their analytic structure encodes dynamical phase behaviour. This ‘thermodynamics of trajectories’ approach is to trajectories and dynamics what the equilibrium ensemble method of statistical mechanics is to configurations and statics. Here we show that, just like in the static case, there are a variety of alternative ensembles of trajectories, each defined by their global constraints, with that of trajectories of fixed total time being just one of these. We show how the LD functions that describe an ensemble of trajectories where some time-extensive quantity is constant (and large) but where total observation time fluctuates can be mapped to those of the fixed-time ensemble. We discuss how the correspondence between generalized ensembles can be exploited in path sampling schemes for generating rare dynamical trajectories.

Proximate composition, energetic value, and relative abundance of prey fish from the inshore eastern Bering Sea: Implications for piscivorous predators

USGS Publications Warehouse

Ball, J.R.; Esler, Daniel N.; Schmutz, J.A.

2007-01-01

Changing ocean conditions and subsequent shifts in forage fish communities have been linked to numerical declines of some piscivorous marine birds and mammals in the North Pacific. However, limited information about fish communities is available for some regions, including nearshore waters of the eastern Bering Sea, where many piscivores reside. We determined proximate composition and energetic value of a suite of potential forage fish collected from an estuary on the Yukon-Kuskokwim Delta, Alaska, during 2002 and 2003. Across species, energy density ranged from 14.5 to 20.7 kJ g−1 dry mass and varied primarily as a function of lipid content. Total energy content was strongly influenced by body length and we provide species-specific predictive models of total energy based on this relationship; some models may be improved further by incorporating year and date effects. Based on observed energetic differences, we conclude that variation in fish size, quantity, and species composition of the prey community could have important consequences for piscivorous predators.

Optimal design of a magnetorheological damper used in smart prosthetic knees

NASA Astrophysics Data System (ADS)

Gao, Fei; Liu, Yan-Nan; Liao, Wei-Hsin

2017-03-01

In this paper, a magnetorheological (MR) damper is optimally designed for use in smart prosthetic knees. The objective of optimization is to minimize the total energy consumption during one gait cycle and weight of the MR damper. Firstly, a smart prosthetic knee employing a DC motor, MR damper and springs is developed based on the kinetics characteristics of human knee during walking. Then the function of the MR damper is analyzed. In the initial stance phase and swing phase, the MR damper is powered off (off-state). While during the late stance phase, the MR damper is powered on to work as a clutch (on-state). Based on the MR damper model as well as the prosthetic knee model, the instantaneous energy consumption of the MR damper is derived in the two working states. Then by integrating in one gait cycle, the total energy consumption is obtained. Particle swarm optimization algorithm is used to optimize the geometric dimensions of MR damper. Finally, a prototype of the optimized MR damper is fabricated and tested with comparison to simulation.

Nutritional support and quality of life in stable chronic obstructive pulmonary disease (COPD) patients.

PubMed

Planas, Mercé; Alvarez, J; García-Peris, P A; de la Cuerda, C; de Lucas, P; Castellà, M; Canseco, F; Reyes, L

2005-06-01

Nutritional depletion is a common problem in chronic obstructive pulmonary disease (COPD) patients. It is caused, to a large extent, by an imbalance between low-energy intake and high-energy requirements. This problem adversely affects morbidity and mortality. However, the use of nutritional supplements to reach their energy necessities requires optimisation between positive and adverse effects on outcome before being used systematically as part of their comprehensive care. The aim of our study was to investigate the effects of oral nutritional repletion on quality of life in stable COPD patients. Prospective, randomised and multi-centre study. Stable COPD patients with a body mass index 22, a fat-free mass index 16, and/or a recent involuntary weight loss (5% during last month, or 10% during the last 3 months) were studied. Exclusion criteria were to present signs of an airway infection, to have a cardiovascular, neurological, or endocrine disease, to be treated with oral steroids, immunosuppressors or oxygen therapy at home, and to receive nutritional supplements. During 12 weeks, patients were encouraged to ingest a total daily defined energy intake. Randomly, in patients from group A the total daily energy load was Resting Energy Expenditure (REE)x1.7, and those from group B, REE x1.3. Total daily energy intake was achieved with regular food plus, if necessary, oral nutritional supplement rich in proteins (with 50% of whey protein), with predominance of carbohydrates over fat, and enriched in antioxidants. Primary end-point variable was quality of life. Secondary end-point outcomes included body weight, body composition, lung function, handgrip strength, and compliance with the energy intake previously planned. Data were treated with a SAS System. Student's test, Wilcoxon's rank sum test, and Mann-Whitney's test were used. At baseline both groups of patients were comparable. All patients needed oral nutritional supplements to achieve total daily defined energy intake. After 12 weeks of follow-up, patients in both groups significantly increased energy intake. Patients in group A increased body weight (P=0.001), triceps skin fold thickness (P=0.009) and body fat mass (P=0.02), and decreased body fat-free mass index (P=0.02). In this group a marked increase in airflow limitation was observed. A tendency to increase body weight and handgrip strength, and to decrease airflow limitation was observed in patients from group B. Furthermore, patients in the later group showed a significant improvement in the feeling of control over the disease (P=0.007) and a tendency to better the other criteria in a quality of life scale. According to our results, total daily energy intake of REE x 1.3 is preferable to REE x 1.7 in mild stable COPD patients. The administration of oral nutritional supplements, rich in proteins (with 50% of whey protein), with predominance of carbohydrates over fat, and enriched in antioxidants, to achieve total daily defined energy intake in patients in group B was followed by a significant improvement of one criteria (mastery) among many others in a quality of life scale.

AdS Black Disk Model for Small-x Deep Inelastic Scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cornalba, Lorenzo; Costa, Miguel S.; Penedones, Joao

2010-08-13

Using the approximate conformal invariance of QCD at high energies we consider a simple anti-de Sitter black disk model to describe saturation in deep inelastic scattering. Deep inside saturation the structure functions have the same power law scaling, F{sub T}{approx}F{sub L}{approx}x{sup -{omega}}, where {omega} is related to the expansion rate of the black disk with energy. Furthermore, the ratio F{sub L}/F{sub T} is given by the universal value (1+{omega}/3+{omega}), independently of the target. For {gamma}*-{gamma}* scattering at high energies we obtain explicit expressions and ratios for the total cross sections of transverse and longitudinal photons in terms of the singlemore » parameter {omega}.« less

Local structure of In0.5Ga0.5As from joint high-resolution and differential pair distribution function analysis

NASA Astrophysics Data System (ADS)

Petkov, V.; Jeong, I.-K.; Mohiuddin-Jacobs, F.; Proffen, Th.; Billinge, S. J. L.; Dmowski, W.

2000-07-01

High resolution total and indium differential atomic pair distribution functions (PDFs) for In0.5Ga0.5As alloys have been obtained by high energy and anomalous x-ray diffraction experiments, respectively. The first peak in the total PDF is resolved as a doublet due to the presence of two distinct bond lengths, In-As and Ga-As. The In differential PDF, which involves only atomic pairs containing In, yields chemical specific information and helps ease the structure data interpretation. Both PDFs have been fit with structure models and the way in that the underlying cubic zinc-blende lattice of In0.5Ga0.5As semiconductor alloy distorts locally to accommodate the distinct In-As and Ga-As bond lengths present has been quantified.

Research on theoretical optimization and experimental verification of minimum resistance hull form based on Rankine source method

NASA Astrophysics Data System (ADS)

Zhang, Bao-Ji; Zhang, Zhu-Xin

2015-09-01

To obtain low resistance and high efficiency energy-saving ship, minimum total resistance hull form design method is studied based on potential flow theory of wave-making resistance and considering the effects of tail viscous separation. With the sum of wave resistance and viscous resistance as objective functions and the parameters of B-Spline function as design variables, mathematical models are built using Nonlinear Programming Method (NLP) ensuring the basic limit of displacement and considering rear viscous separation. We develop ship lines optimization procedures with intellectual property rights. Series60 is used as parent ship in optimization design to obtain improved ship (Series60-1) theoretically. Then drag tests for the improved ship (Series60-1) is made to get the actual minimum total resistance hull form.

A study of the thermal and optical characteristics of radiometric channels for Earth radiation budget applications

NASA Technical Reports Server (NTRS)

Mahan, J. R.; Tira, Nour E.

1991-01-01

An improved dynamic electrothermal model for the Earth Radiation Budget Experiment (ERBE) total, nonscanning channels is formulated. This model is then used to accurately simulate two types of dynamic solar observation: the solar calibration and the so-called pitchover maneuver. Using a second model, the nonscanner active cavity radiometer (ACR) thermal noise is studied. This study reveals that radiative emission and scattering by the surrounding parts of the nonscanner cavity are acceptably small. The dynamic electrothermal model is also used to compute ACR instrument transfer function. Accurate in-flight measurement of this transfer function is shown to depend on the energy distribution over the frequency spectrum of the radiation input function. A new array-type field of view limiter, whose geometry controls the input function, is proposed for in-flight calibration of an ACR and other types of radiometers. The point spread function (PSF) of the ERBE and the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers is computed. The PSF is useful in characterizing the channel optics. It also has potential for recovering the distribution of the radiative flux from Earth by deconvolution.

Deviations from Born-Oppenheimer mass scaling in spectroscopy and ultracold molecular physics

NASA Astrophysics Data System (ADS)

Lutz, Jesse J.; Hutson, Jeremy M.

2016-12-01

We investigate Born-Oppenheimer breakdown (BOB) effects (beyond the usual mass scaling) for the electronic ground states of a series of homonuclear and heteronuclear alkali-metal diatoms, together with the Sr2 and Yb2 diatomics. Several widely available electronic structure software packages are used to calculate the leading contributions to the total isotope shift for commonly occurring isotopologs of each species. Computed quantities include diagonal Born-Oppenheimer corrections (mass shifts) and isotopic field shifts. Mass shifts dominate for light nuclei up to and including K, but field shifts contribute significantly for Rb and Sr and are dominant for Yb. We compare the ab initio mass-shift functions for Li2, LiK and LiRb with spectroscopically derived ground-state BOB functions from the literature. We find good agreement in the values of the functions for LiK and LiRb at their equilibrium geometries, but significant disagreement with the shapes of the functions for all 3 systems. The differences may be due to contributions of nonadiabatic terms to the empirical BOB functions. We present a semiclassical model for the effect of BOB corrections on the binding energies of near-threshold states and the positions of zero-energy Feshbach resonances.

The optimized effective potential and the self-interaction correction in density functional theory: Application to molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garza, Jorge; Nichols, Jeffrey A.; Dixon, David A.

2000-05-08

The Krieger, Li, and Iafrate approximation to the optimized effective potential including the self-interaction correction for density functional theory has been implemented in a molecular code, NWChem, that uses Gaussian functions to represent the Kohn and Sham spin-orbitals. The differences between the implementation of the self-interaction correction in codes where planewaves are used with an optimized effective potential are discussed. The importance of the localization of the spin-orbitals to maximize the exchange-correlation of the self-interaction correction is discussed. We carried out exchange-only calculations to compare the results obtained with these approximations, and those obtained with the local spin density approximation,more » the generalized gradient approximation and Hartree-Fock theory. Interesting results for the energy difference (GAP) between the highest occupied molecular orbital, HOMO, and the lowest unoccupied molecular orbital, LUMO, (spin-orbital energies of closed shell atoms and molecules) using the optimized effective potential and the self-interaction correction have been obtained. The effect of the diffuse character of the basis set on the HOMO and LUMO eigenvalues at the various levels is discussed. Total energies obtained with the optimized effective potential and the self-interaction correction show that the exchange energy with these approximations is overestimated and this will be an important topic for future work. (c) 2000 American Institute of Physics.« less

Measurements of the Total Reaction Cross Sections for 6,8He and 8,9Li Nuclei with Energies of (25-45)A Mev on natAl, natTa and natPb

NASA Astrophysics Data System (ADS)

Erdemchimeg, B.; Artukh, A. G.; Klygin, S. A.; Kononenko, G. A.; Kyslukha, D. A.; Sereda, Yu. M.; Vorontzov, A. N.; Lukyanov, S. M.; Penionzhkevich, Yu. E.; Davaa, S.; Khuukhenkhuu, G.; Borcea, C.; Rotaru, F.; Stanoiu, M.; Martina, L.; Saillant, F.; Raine, B.

2015-06-01

The total nuclear reaction cross sections (σR) measurements have long been of interest since they tell us about the radii and transparency of these nuclei and give clues to understanding of their structure. For studies of unstable nuclei, in particular the physical properties of halo nuclei and the neutron skin thickness, it is valuable to know not only the root-mean-square radii (rms) but it is important to know the details of nucleusnucleus potentials. Our goal was to study total reaction cross sections (σR) by a direct measurement technique (the so-called beam attenuation or transmission method) which allows to extract model independent information. The interaction radii for 6He, 8,9Li were extracted, which are in agreement with the previous measurement at the similar energies (about a few tens of AMeV) Our results show a tendency of increasing radii as function of mass of the secondary targets.

Searching for globally optimal functional forms for interatomic potentials using genetic programming with parallel tempering.

PubMed

Slepoy, A; Peters, M D; Thompson, A P

2007-11-30

Molecular dynamics and other molecular simulation methods rely on a potential energy function, based only on the relative coordinates of the atomic nuclei. Such a function, called a force field, approximately represents the electronic structure interactions of a condensed matter system. Developing such approximate functions and fitting their parameters remains an arduous, time-consuming process, relying on expert physical intuition. To address this problem, a functional programming methodology was developed that may enable automated discovery of entirely new force-field functional forms, while simultaneously fitting parameter values. The method uses a combination of genetic programming, Metropolis Monte Carlo importance sampling and parallel tempering, to efficiently search a large space of candidate functional forms and parameters. The methodology was tested using a nontrivial problem with a well-defined globally optimal solution: a small set of atomic configurations was generated and the energy of each configuration was calculated using the Lennard-Jones pair potential. Starting with a population of random functions, our fully automated, massively parallel implementation of the method reproducibly discovered the original Lennard-Jones pair potential by searching for several hours on 100 processors, sampling only a minuscule portion of the total search space. This result indicates that, with further improvement, the method may be suitable for unsupervised development of more accurate force fields with completely new functional forms. Copyright (c) 2007 Wiley Periodicals, Inc.

Relative emissions intensity of dairy production systems: employing different functional units in life-cycle assessment.

PubMed

Ross, S A; Topp, C F E; Ennos, R A; Chagunda, M G G

2017-08-01

This study aimed to assess the merit and suitability of individual functional units (FU) in expressing greenhouse gas emissions intensity in different dairy production systems. An FU provides a clearly defined and measurable reference to which input and output data are normalised. This enables the results from life-cycle assessment (LCA) of different systems to be treated as functionally equivalent. Although the methodological framework of LCA has been standardised, selection of an appropriate FU remains ultimately at the discretion of the individual study. The aim of the present analysis was to examine the effect of different FU on the emissions intensities of different dairy production systems. Analysis was based on 7 years of data (2004 to 2010) from four Holstein-Friesian dairy systems at Scotland's Rural College's long-term genetic and management systems project, the Langhill herd. Implementation of LCA accounted for the environmental impacts of the whole-farm systems and their production of milk from 'cradle to farm gate'. Emissions intensity was determined as kilograms of carbon dioxide equivalents referenced to six FU: UK livestock units, energy-corrected milk yield, total combined milk solids yield, on-farm land used for production, total combined on- and off-farm land used for production, and the proposed new FU-energy-corrected milk yield per hectare of total land used. Energy-corrected milk was the FU most effective for reflecting differences between the systems. Functional unit that incorporated a land-related aspect did not find difference between systems which were managed under the same forage regime, despite their comprising different genetic lines. Employing on-farm land as the FU favoured grazing systems. The proposed dual FU combining both productivity and land use did not differentiate between emissions intensity of systems as effectively as the productivity-based units. However, this dual unit displayed potential to quantify in a simple way the positive or negative outcome of trade-offs between land and production efficiencies, in which improvement in emissions intensity using one FU may be accompanied by deterioration using another FU. The perceived environmental efficiencies of different dairy production systems in terms of their emissions intensities were susceptible to change based upon the FU employed, and hence the FU used in any study needs to be taken into account in the interpretation of results.

Comprehensive overview of the Point-by-Point model of prompt emission in fission

NASA Astrophysics Data System (ADS)

Tudora, A.; Hambsch, F.-J.

2017-08-01

The investigation of prompt emission in fission is very important in understanding the fission process and to improve the quality of evaluated nuclear data required for new applications. In the last decade remarkable efforts were done for both the development of prompt emission models and the experimental investigation of the properties of fission fragments and the prompt neutrons and γ-ray emission. The accurate experimental data concerning the prompt neutron multiplicity as a function of fragment mass and total kinetic energy for 252Cf(SF) and 235 ( n, f) recently measured at JRC-Geel (as well as other various prompt emission data) allow a consistent and very detailed validation of the Point-by-Point (PbP) deterministic model of prompt emission. The PbP model results describe very well a large variety of experimental data starting from the multi-parametric matrices of prompt neutron multiplicity ν (A,TKE) and γ-ray energy E_{γ}(A,TKE) which validate the model itself, passing through different average prompt emission quantities as a function of A ( e.g., ν(A), E_{γ}(A), < ɛ > (A) etc.), as a function of TKE ( e.g., ν (TKE), E_{γ}(TKE)) up to the prompt neutron distribution P (ν) and the total average prompt neutron spectrum. The PbP model does not use free or adjustable parameters. To calculate the multi-parametric matrices it needs only data included in the reference input parameter library RIPL of IAEA. To provide average prompt emission quantities as a function of A, of TKE and total average quantities the multi-parametric matrices are averaged over reliable experimental fragment distributions. The PbP results are also in agreement with the results of the Monte Carlo prompt emission codes FIFRELIN, CGMF and FREYA. The good description of a large variety of experimental data proves the capability of the PbP model to be used in nuclear data evaluations and its reliability to predict prompt emission data for fissioning nuclei and incident energies for which the experimental information is completely missing. The PbP treatment can also provide input parameters of the improved Los Alamos model with non-equal residual temperature distributions recently reported by Madland and Kahler, especially for fissioning nuclei without any experimental information concerning the prompt emission.

On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: I. Cosmic microwave background radiation

NASA Astrophysics Data System (ADS)

Fisenko, Anatoliy I.; Lemberg, Vladimir

2014-07-01

Using the explicit form of the functions to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies v 1≤ v≤ v 2 are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60-600 GHz frequency interval at the temperature T=2.72548 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant σ are calculated. In the case of the dipole spectrum, the constants a and σ, and the radiative and thermodynamic properties of the CMB radiation are obtained using the mean amplitude T amp=3.358 mK. It is shown that the Doppler shift leads to a renormalization of the radiation density constant a, the Stefan-Boltzmann constant σ, and the corresponding constants for the thermodynamic functions. The expressions for new astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of CMB photons are obtained. The radiative and thermodynamic properties of the Cosmic Microwave Background radiation for the monopole and dipole spectra at redshift z≈1089 are calculated.

The Relationship between Maternal Nutrition during Pregnancy and Offspring Kidney Structure and Function in Humans: A Systematic Review

PubMed Central

Lee, Yu Qi; Collins, Clare E.; Gordon, Adrienne; Rae, Kym M.; Pringle, Kirsty G.

2018-01-01

The intrauterine environment is critical for fetal growth and organ development. Evidence from animal models indicates that the developing kidney is vulnerable to suboptimal maternal nutrition and changes in health status. However, evidence from human studies are yet to be synthesised. Therefore, the aim of the current study was to systematically review current research on the relationship between maternal nutrition during pregnancy and offspring kidney structure and function in humans. A search of five databases identified 9501 articles, of which three experimental and seven observational studies met the inclusion criteria. Nutrients reviewed to date included vitamin A (n = 3), folate and vitamin B12 (n = 2), iron (n = 1), vitamin D (n = 1), total energy (n = 2) and protein (n = 1). Seven studies were assessed as being of “positive” and three of “neutral” quality. A variety of populations were studied, with limited studies investigating maternal nutrition during pregnancy, while measurements of offspring kidney outcomes were diverse across studies. There was a lack of consistency in the timing of follow-up for offspring kidney structure and/or function assessments, thus limiting comparability between studies. Deficiencies in maternal folate, vitamin A, and total energy during pregnancy were associated with detrimental impacts on kidney structure and function, measured by kidney volume, proteinuria, eGFRcystC and mean creatinine clearance in the offspring. Additional experimental and longitudinal prospective studies are warranted to confirm this relationship, especially in Indigenous populations where the risk of renal disease is greater. PMID:29466283

Toward the identification of molecular cogs.

PubMed

Dziubiński, Maciej; Lesyng, Bogdan

2016-04-05

Computer simulations of molecular systems allow determination of microscopic interactions between individual atoms or groups of atoms, as well as studies of intramolecular motions. Nevertheless, description of structural transformations at the mezoscopic level and identification of causal relations associated with these transformations is very difficult. Structural and functional properties are related to free energy changes. Therefore, to better understand structural and functional properties of molecular systems, it is required to deepen our knowledge of free energy contributions arising from molecular subsystems in the course of structural transformations. The method presented in this work quantifies the energetic contribution of each pair of atoms to the total free energy change along a given collective variable. Next, with the help of a genetic clustering algorithm, the method proposes a division of the system into two groups of atoms referred to as molecular cogs. Atoms which cooperate to push the system forward along a collective variable are referred to as forward cogs, and those which work in the opposite direction as reverse cogs. The procedure was tested on several small molecules for which the genetic clustering algorithm successfully found optimal partitionings into molecular cogs. The primary result of the method is a plot depicting the energetic contributions of the identified molecular cogs to the total Potential of Mean Force (PMF) change. Case-studies presented in this work should help better understand the implications of our approach, and were intended to pave the way to a future, publicly available implementation. © 2015 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Senesi, Roberto; Flammini, Davide; Kolesnikov, Alexander I.

The OH stretching vibrational spectrum of water was measured in a wide range of temperatures across the triple point, 269 K < T < 296 K, using Inelastic Neutron Scattering (INS). The hydrogen projected density of states and the proton mean kinetic energy, _OH, were determined for the first time within the framework of a harmonic description of the proton dynamics. We found that in the liquid the value of _OH is nearly constant as a function of T, indicating that quantum effects on the OH stretching frequency are weakly dependent on temperature. In the case of ice, ab initiomore » electronic structure calculations, using non-local van der Waals functionals, provided _OH values in agreement with INS experiments. We also found that the ratio of the stretching (_OH) to the total (_exp) kinetic energy, obtained from the present measurements, increases in going from ice, where hydrogen bonding is the strongest, to the liquid at ambient conditions and then to the vapour phase, where hydrogen bonding is the weakest. The same ratio was also derived from the combination of previous deep inelastic neutron scattering data, which does not rely upon the harmonic approximation, and the present measurements. We found that the ratio of stretching to the total kinetic energy shows a minimum in the metastable liquid phase. This finding suggests that the strength of intermolecular interactions increases in the supercooled phase, with respect to that in ice, contrary to the accepted view that supercooled water exhibits weaker hydrogen bonding than ice.« less

Correlating molecular spectroscopy and molecular chemometrics to explore carbohydrate functional groups and utilization of coproducts from biofuel and biobrewing processing.

PubMed

Chen, Limei; Zhang, Xuewei; Yu, Peiqiang

2014-06-04

Dried distillers grains with solubles (DDGS) was coproducts from bioethanol and biobrewing industry. It was an excellent resource of protein and energy feedstuff in China. Conventional studies often focus on traditional nutritional profiles. To data, there is little research on molecular structure-nutrition interaction of carbohydrate in coproducts. In this study, five kinds of corn-grain based DDGS and two kinds of barley-grain based DDGS were collected from different manufactures in the north of China. They were coded as "1, 2, 3, 4, 5, 6, and 7", respectively. The primary purposes of this project were to investigate the molecular structure-nutrition interaction of carbohydrate in coproducts, in terms of (1) carbohydrate-related chemical composition and nutrient profiles, (2) predicted values for energy in coproducts for animal, and (3) in situ digestion of dry matter. The result showed that acid detergent fiber content in corn DDGS and barley DDGS had negative correlation with structural carbohydrate peak area, cellulose compounds, and carbohydrate component peaks (first, second, and total peak area), which were measured with molecular spectroscopy. The correlation between carbohydrate peak area (second and total) and digestible fiber (tdNDF) were negative. There were no correlation between carbohydrate spectral intensities and energy values, carbohydrate subfractions partitioned by CNCPS system, and in situ rumen degradation. The results indicate that carbohydrate spectral profiles (functional groups) are associated with the carbohydrate nutritive values in coproducts from biofuel and biobrewing processing.

Electronic Characterization of Defects in Narrow Gap Semiconductors-Comparison of Electronic Energy Levels and Formation Energies in Mercury Cadmium Telluride, Mercury Zinc Telluride, and Mercury Zinc Selenide

NASA Technical Reports Server (NTRS)

Patterson, James D.

1996-01-01

We have used a Green's function technique to calculate the energy levels and formation energy of deep defects in the narrow gap semiconductors mercury cadmium telluride (MCT), mercury zinc telluride (MZT) and mercury zinc selenide (MZS). The formation energy is calculated from the difference between the total energy with an impurity cluster and the total energy for the perfect crystal. Substitutional (including antisite), interstitial (self and foreign), and vacancy deep defects are considered. Relaxation effects are calculated (with molecular dynamics). By use of a pseudopotential, we generalize the ideal vacancy model so as to be able to consider relaxation for vacancies. Different charge states are considered and the charged state energy shift (as computed by a modified Haldane-Anderson model) can be twice that due to relaxation. Different charged states for vacancies were not calculated to have much effect on the formation energy. For all cases we find deep defects in the energy gap only for cation site s-like orbitals or anion site p-like orbitals, and for the substitutional case only the latter are appreciably effected by relaxation. For most cases for MCT, MZT, MZS, we consider x (the concentration of Cd or Zn) in the range appropriate for a band gap of 0.1 eV. For defect energy levels, the absolute accuracy of our results is limited, but the precision is good, and hence chemical trends are accurately predicted. For the same reason, defect formation energies are more accurately predicted than energy level position. We attempt, in Appendix B, to calculate vacancy formation energies using relatively simple chemical bonding ideas due to Harrison. However, these results are only marginally accurate for estimating vacancy binding energies. Appendix C lists all written reports and publications produced for the grant. We include abstracts and a complete paper that summarizes our work which is not yet available.

Essential energy space random walk via energy space metadynamics method to accelerate molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Li, Hongzhi; Min, Donghong; Liu, Yusong; Yang, Wei

2007-09-01

To overcome the possible pseudoergodicity problem, molecular dynamic simulation can be accelerated via the realization of an energy space random walk. To achieve this, a biased free energy function (BFEF) needs to be priori obtained. Although the quality of BFEF is essential for sampling efficiency, its generation is usually tedious and nontrivial. In this work, we present an energy space metadynamics algorithm to efficiently and robustly obtain BFEFs. Moreover, in order to deal with the associated diffusion sampling problem caused by the random walk in the total energy space, the idea in the original umbrella sampling method is generalized to be the random walk in the essential energy space, which only includes the energy terms determining the conformation of a region of interest. This essential energy space generalization allows the realization of efficient localized enhanced sampling and also offers the possibility of further sampling efficiency improvement when high frequency energy terms irrelevant to the target events are free of activation. The energy space metadynamics method and its generalization in the essential energy space for the molecular dynamics acceleration are demonstrated in the simulation of a pentanelike system, the blocked alanine dipeptide model, and the leucine model.

Therapeutic effects of short-term monochromatic infrared energy therapy on patients with knee osteoarthritis: a double-blind, randomized, placebo-controlled study.

PubMed

Hsieh, Ru-Lan; Lo, Min-Tzu; Lee, Wen-Chung; Liao, Wei-Cheng

2012-11-01

Randomized, double-blind, placebo-controlled study. To examine the short-term therapeutic effects of monochromatic infrared energy (MIRE) on participants with knee osteoarthritis (OA). Patients were assessed according to the International Classification of Functioning, Disability and Health. MIRE is commonly used in therapy for patients with peripheral neuropathies. However, research has not focused intensively on the therapeutic effects of MIRE in patients with knee OA. This study enrolled 73 participants with knee OA. Participants received six 40-minute sessions of active or placebo MIRE treatment (890-nm wavelength; power, 6.24 W; energy density, 2.08 J/cm2/min; total energy, 83.2 J/cm2) over the knee joints for 2 weeks. International Classification of Functioning, Disability and Health-related outcomes were collected weekly over 4 weeks using the Knee injury and Osteoarthritis Outcome Score, Lysholm Knee Scale, Hospital Anxiety and Depression Scale, Multidimensional Fatigue Inventory, Chronic Pain Grade questionnaire, World Health Organization Quality of Life-brief version, and OA Quality of Life Questionnaire. Data were analyzed by repeated-measures analysis of variance. No statistically significant differences were found for the interaction of group by time for Knee injury and Osteoarthritis Outcome Score scores, including pain, other symptoms, function in daily living, function in sport and recreation, and knee-related quality of life. Scores on the Lysholm Knee Scale, Hospital Anxiety and Depression Scale, Multidimensional Fatigue Inventory, Chronic Pain Grade questionnaire, World Health Organization Quality of Life-brief version, and OA Quality of Life Questionnaire also showed no significant differences between the 2 groups at any of the 4 follow-up assessments. Short-term MIRE therapy provided no beneficial effects to body functions, activities, participation, and quality of life in patients with knee OA.

Differences in Military Obstacle Course Performance Between Three Energy-Storing and Shock-Adapting Prosthetic Feet in High-Functioning Transtibial Amputees: A Double-Blind, Randomized Control Trial.

PubMed

Highsmith, M Jason; Kahle, Jason T; Miro, Rebecca M; Lura, Derek J; Carey, Stephanie L; Wernke, Matthew M; Kim, Seok Hun; Quillen, William S

2016-11-01

Approximately 683 persons engaged in military service experienced transtibial amputation (TTA) related to recent war in Iraq and Afghanistan. Military TTAs function at a level beyond basic ambulation. No empirical data demonstrate which higher functioning prosthetic feet maximize injured service personnel's ability to continue performing at a level commensurate with return to duty. This study's purpose was to determine which of three high-functioning, energy-storing prosthetic feet maximize performance and preference in a field obstacle course (OC) and to quantify physical performance differences between TTAs and high-functioning nonamputees. A randomized, double-blind, repeated measures experimental design compared three prosthetic feet (Ossur Variflex, Endolite Elite Blade, and Ossur Re-Flex Rotate) during performance on a field OC. TTAs accommodated with study feet and the OC before assessment. 14 TTAs and 14 nonamputee controls completed the course. Subjective and objective performance differences were compared across feet conditions and between groups. Total OC completion times were similar between prosthetic feet: Elite-Blade (419 seconds ± 130), Variflex (425 seconds ± 144), and Re-Flex Rotate (444 seconds ± 220). Controls' OC completion time (287.2 seconds ± 58) was less (p ≤ 0.05) than TTA times. In total, controls had faster completion times (p ≤ 0.05) compared to all prosthetic feet conditions in 13/17 obstacles. Re-Flex Rotate had 2 additional obstacles different (p ≤ 0.05) than controls and required more time to complete. Median RPE values were lower (p ≤ 0.05) for controls than TTA regardless of foot. Regarding foot preference for OC completion, 7/14 (50%) preferred Elite Blade, 5/14 (36%) preferred Re-Flex Rotate, and the remaining 2/14 (14%) preferred Variflex. Controls completed the OC faster and with less effort than TTAs regardless of prosthetic foot. No clear differences in prosthetic feet emerged during OC completion; however, individual task performance, perceived effort, and preference resulted in trends of slight performance improvement with and preference for Elite Blade, a dual function energy-storing and return foot combined with vertical shock absorption. Understanding how to maximally improve performance in such functional tasks may allow service members to best sustain physical fitness, return to their military occupational specialty and possibly in-theater duty. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Compact Q-balls in the complex signum-Gordon model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arodz, H.; Lis, J.

2008-05-15

We discuss Q-balls in the complex signum-Gordon model in d-dimensional space for d=1, 2, 3. The Q-balls have strictly finite size. Their total energy is a powerlike function of the conserved U(1) charge with the exponent equal to (d+2)(d+3){sup -1}. In the cases d=1 and d=3 explicit analytic solutions are presented.

Machine learning predictions of molecular properties: Accurate many-body potentials and nonlocality in chemical space

DOE PAGES

Hansen, Katja; Biegler, Franziska; Ramakrishnan, Raghunathan; ...

2015-06-04

Simultaneously accurate and efficient prediction of molecular properties throughout chemical compound space is a critical ingredient toward rational compound design in chemical and pharmaceutical industries. Aiming toward this goal, we develop and apply a systematic hierarchy of efficient empirical methods to estimate atomization and total energies of molecules. These methods range from a simple sum over atoms, to addition of bond energies, to pairwise interatomic force fields, reaching to the more sophisticated machine learning approaches that are capable of describing collective interactions between many atoms or bonds. In the case of equilibrium molecular geometries, even simple pairwise force fields demonstratemore » prediction accuracy comparable to benchmark energies calculated using density functional theory with hybrid exchange-correlation functionals; however, accounting for the collective many-body interactions proves to be essential for approaching the “holy grail” of chemical accuracy of 1 kcal/mol for both equilibrium and out-of-equilibrium geometries. This remarkable accuracy is achieved by a vectorized representation of molecules (so-called Bag of Bonds model) that exhibits strong nonlocality in chemical space. The same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies.« less

Signatures of van der Waals binding: A coupling-constant scaling analysis

NASA Astrophysics Data System (ADS)

Jiao, Yang; Schröder, Elsebeth; Hyldgaard, Per

2018-02-01

The van der Waals (vdW) density functional (vdW-DF) method [Rep. Prog. Phys. 78, 066501 (2015), 10.1088/0034-4885/78/6/066501] describes dispersion or vdW binding by tracking the effects of an electrodynamic coupling among pairs of electrons and their associated exchange-correlation holes. This is done in a nonlocal-correlation energy term Ecnl, which permits density functional theory calculation in the Kohn-Sham scheme. However, to map the nature of vdW forces in a fully interacting materials system, it is necessary to also account for associated kinetic-correlation energy effects. Here, we present a coupling-constant scaling analysis, which permits us to compute the kinetic-correlation energy Tcnl that is specific to the vdW-DF account of nonlocal correlations. We thus provide a more complete spatially resolved analysis of the electrodynamical-coupling nature of nonlocal-correlation binding, including vdW attraction, in both covalently and noncovalently bonded systems. We find that kinetic-correlation energy effects play a significant role in the account of vdW or dispersion interactions among molecules. Furthermore, our mapping shows that the total nonlocal-correlation binding is concentrated to pockets in the sparse electron distribution located between the material fragments.

The MONET code for the evaluation of the dose in hadrontherapy

NASA Astrophysics Data System (ADS)

Embriaco, A.

2018-01-01

The MONET is a code for the computation of the 3D dose distribution for protons in water. For the lateral profile, MONET is based on the Molière theory of multiple Coulomb scattering. To take into account also the nuclear interactions, we add to this theory a Cauchy-Lorentz function, where the two parameters are obtained by a fit to a FLUKA simulation. We have implemented the Papoulis algorithm for the passage from the projected to a 2D lateral distribution. For the longitudinal profile, we have implemented a new calculation of the energy loss that is in good agreement with simulations. The inclusion of the straggling is based on the convolution of energy loss with a Gaussian function. In order to complete the longitudinal profile, also the nuclear contributions are included using a linear parametrization. The total dose profile is calculated in a 3D mesh by evaluating at each depth the 2D lateral distributions and by scaling them at the value of the energy deposition. We have compared MONET with FLUKA in two cases: a single Gaussian beam and a lateral scan. In both cases, we have obtained a good agreement for different energies of protons in water.

Machine Learning Predictions of Molecular Properties: Accurate Many-Body Potentials and Nonlocality in Chemical Space

PubMed Central

2015-01-01

Simultaneously accurate and efficient prediction of molecular properties throughout chemical compound space is a critical ingredient toward rational compound design in chemical and pharmaceutical industries. Aiming toward this goal, we develop and apply a systematic hierarchy of efficient empirical methods to estimate atomization and total energies of molecules. These methods range from a simple sum over atoms, to addition of bond energies, to pairwise interatomic force fields, reaching to the more sophisticated machine learning approaches that are capable of describing collective interactions between many atoms or bonds. In the case of equilibrium molecular geometries, even simple pairwise force fields demonstrate prediction accuracy comparable to benchmark energies calculated using density functional theory with hybrid exchange-correlation functionals; however, accounting for the collective many-body interactions proves to be essential for approaching the “holy grail” of chemical accuracy of 1 kcal/mol for both equilibrium and out-of-equilibrium geometries. This remarkable accuracy is achieved by a vectorized representation of molecules (so-called Bag of Bonds model) that exhibits strong nonlocality in chemical space. In addition, the same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies. PMID:26113956

Transition sum rules in the shell model

NASA Astrophysics Data System (ADS)

Lu, Yi; Johnson, Calvin W.

2018-03-01

An important characterization of electromagnetic and weak transitions in atomic nuclei are sum rules. We focus on the non-energy-weighted sum rule (NEWSR), or total strength, and the energy-weighted sum rule (EWSR); the ratio of the EWSR to the NEWSR is the centroid or average energy of transition strengths from an nuclear initial state to all allowed final states. These sum rules can be expressed as expectation values of operators, which in the case of the EWSR is a double commutator. While most prior applications of the double commutator have been to special cases, we derive general formulas for matrix elements of both operators in a shell model framework (occupation space), given the input matrix elements for the nuclear Hamiltonian and for the transition operator. With these new formulas, we easily evaluate centroids of transition strength functions, with no need to calculate daughter states. We apply this simple tool to a number of nuclides and demonstrate the sum rules follow smooth secular behavior as a function of initial energy, as well as compare the electric dipole (E 1 ) sum rule against the famous Thomas-Reiche-Kuhn version. We also find surprising systematic behaviors for ground-state electric quadrupole (E 2 ) centroids in the s d shell.

Near-barrier Fusion Evaporation and Fission of 28Si+174Yb and 32S+170Er

NASA Astrophysics Data System (ADS)

Wang, Dongxi; Lin, Chengjian; Jia, Huiming; Ma, Nanru; Sun, Lijie; Xu, Xinxing; Yang, Lei; Yang, Feng; Zhang, Huanqiao; Bao, Pengfei

2017-11-01

Fusion evaporation residues and fission fragments have been measured, respectively, at energies around the Coulomb barrier for the 28Si+174Yb and 32S+170Er systems forming the same compound nucleus 202Po. The excitation function of fusion evaporation, fission as well as capture reactions were deduced. Coupled-channels analyses reveal that couplings to the deformations of targets and the two-phonon states of projectiles contribute much to the enhancement of capture cross sections at sub-barrier energies. The mass and total kinetic energy of fission fragments were deduced by the time-difference method assuming full momentum transfer in a two-body kinematics. The mass-energy and mass-angle distributions were obtained and no obvious quasi-fission components were observed in this bombarding energy range. Further, mass distributions of fission fragments were fitted to extract their widths. Results show that the mass widths decrease monotonically with decreasing energy, but might start to increase when Ec.m./VB < 0.95 for both systems.

Phenomenological scattering-rate model for the simulation of the current density and emission power in mid-infrared quantum cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurlov, S. S.; Institute of Semiconductor Physics, National Academy of Sciences, pr. Nauki 45, Kiev-03028; Flores, Y. V.

2016-04-07

A phenomenological scattering-rate model introduced for terahertz quantum cascade lasers (QCLs) [Schrottke et al., Semicond. Sci. Technol. 25, 045025 (2010)] is extended to mid-infrared (MIR) QCLs by including the energy dependence of the intersubband scattering rates for energies higher than the longitudinal optical phonon energy. This energy dependence is obtained from a phenomenological fit of the intersubband scattering rates based on published lifetimes of a number of MIR QCLs. In our approach, the total intersubband scattering rate is written as the product of the exchange integral for the squared moduli of the envelope functions and a phenomenological factor that dependsmore » only on the transition energy. Using the model to calculate scattering rates and imposing periodical boundary conditions on the current density, we find a good agreement with low-temperature data for current-voltage, power-current, and energy-photon flux characteristics for a QCL emitting at 5.2 μm.« less

Estimation of Transpiration and Water Use Efficiency Using Satellite and Field Observations

NASA Technical Reports Server (NTRS)

Choudhury, Bhaskar J.; Quick, B. E.

2003-01-01

Structure and function of terrestrial plant communities bring about intimate relations between water, energy, and carbon exchange between land surface and atmosphere. Total evaporation, which is the sum of transpiration, soil evaporation and evaporation of intercepted water, couples water and energy balance equations. The rate of transpiration, which is the major fraction of total evaporation over most of the terrestrial land surface, is linked to the rate of carbon accumulation because functioning of stomata is optimized by both of these processes. Thus, quantifying the spatial and temporal variations of the transpiration efficiency (which is defined as the ratio of the rate of carbon accumulation and transpiration), and water use efficiency (defined as the ratio of the rate of carbon accumulation and total evaporation), and evaluation of modeling results against observations, are of significant importance in developing a better understanding of land surface processes. An approach has been developed for quantifying spatial and temporal variations of transpiration, and water-use efficiency based on biophysical process-based models, satellite and field observations. Calculations have been done using concurrent meteorological data derived from satellite observations and four dimensional data assimilation for four consecutive years (1987-1990) over an agricultural area in the Northern Great Plains of the US, and compared with field observations within and outside the study area. The paper provides substantive new information about interannual variation, particularly the effect of drought, on the efficiency values at a regional scale.

Redox potentials and pKa for benzoquinone from density functional theory based molecular dynamics.

PubMed

Cheng, Jun; Sulpizi, Marialore; Sprik, Michiel

2009-10-21

The density functional theory based molecular dynamics (DFTMD) method for the computation of redox free energies presented in previous publications and the more recent modification for computation of acidity constants are reviewed. The method uses a half reaction scheme based on reversible insertion/removal of electrons and protons. The proton insertion is assisted by restraining potentials acting as chaperones. The procedure for relating the calculated deprotonation free energies to Brønsted acidities (pK(a)) and the oxidation free energies to electrode potentials with respect to the normal hydrogen electrode is discussed in some detail. The method is validated in an application to the reduction of aqueous 1,4-benzoquinone. The conversion of hydroquinone to quinone can take place via a number of alternative pathways consisting of combinations of acid dissociations, oxidations, or dehydrogenations. The free energy changes of all elementary steps (ten in total) are computed. The accuracy of the calculations is assessed by comparing the energies of different pathways for the same reaction (Hess's law) and by comparison to experiment. This two-sided test enables us to separate the errors related with the restrictions on length and time scales accessible to DFTMD from the errors introduced by the DFT approximation. It is found that the DFT approximation is the main source of error for oxidation free energies.

Planning energy-efficient bipedal locomotion on patterned terrain

NASA Astrophysics Data System (ADS)

Zamani, Ali; Bhounsule, Pranav A.; Taha, Ahmad

2016-05-01

Energy-efficient bipedal walking is essential in realizing practical bipedal systems. However, current energy-efficient bipedal robots (e.g., passive-dynamics-inspired robots) are limited to walking at a single speed and step length. The objective of this work is to address this gap by developing a method of synthesizing energy-efficient bipedal locomotion on patterned terrain consisting of stepping stones using energy-efficient primitives. A model of Cornell Ranger (a passive-dynamics inspired robot) is utilized to illustrate our technique. First, an energy-optimal trajectory control problem for a single step is formulated and solved. The solution minimizes the Total Cost Of Transport (TCOT is defined as the energy used per unit weight per unit distance travelled) subject to various constraints such as actuator limits, foot scuffing, joint kinematic limits, ground reaction forces. The outcome of the optimization scheme is a table of TCOT values as a function of step length and step velocity. Next, we parameterize the terrain to identify the location of the stepping stones. Finally, the TCOT table is used in conjunction with the parameterized terrain to plan an energy-efficient stepping strategy.

In silico evolution of the Drosophila gap gene regulatory sequence under elevated mutational pressure.

PubMed

Chertkova, Aleksandra A; Schiffman, Joshua S; Nuzhdin, Sergey V; Kozlov, Konstantin N; Samsonova, Maria G; Gursky, Vitaly V

2017-02-07

Cis-regulatory sequences are often composed of many low-affinity transcription factor binding sites (TFBSs). Determining the evolutionary and functional importance of regulatory sequence composition is impeded without a detailed knowledge of the genotype-phenotype map. We simulate the evolution of regulatory sequences involved in Drosophila melanogaster embryo segmentation during early development. Natural selection evaluates gene expression dynamics produced by a computational model of the developmental network. We observe a dramatic decrease in the total number of transcription factor binding sites through the course of evolution. Despite a decrease in average sequence binding energies through time, the regulatory sequences tend towards organisations containing increased high affinity transcription factor binding sites. Additionally, the binding energies of separate sequence segments demonstrate ubiquitous mutual correlations through time. Fewer than 10% of initial TFBSs are maintained throughout the entire simulation, deemed 'core' sites. These sites have increased functional importance as assessed under wild-type conditions and their binding energy distributions are highly conserved. Furthermore, TFBSs within close proximity of core sites exhibit increased longevity, reflecting functional regulatory interactions with core sites. In response to elevated mutational pressure, evolution tends to sample regulatory sequence organisations with fewer, albeit on average, stronger functional transcription factor binding sites. These organisations are also shaped by the regulatory interactions among core binding sites with sites in their local vicinity.