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Sample records for density energy-level

  1. Analytic energy-level densities of separable harmonic oscillators including approximate hindered rotor corrections

    NASA Astrophysics Data System (ADS)

    Döntgen, M.

    2016-09-01

    Energy-level densities are key for obtaining various chemical properties. In chemical kinetics, energy-level densities are used to predict thermochemistry and microscopic reaction rates. Here, an analytic energy-level density formulation is derived using inverse Laplace transformation of harmonic oscillator partition functions. Anharmonic contributions to the energy-level density are considered approximately using a literature model for the transition from harmonic to free motions. The present analytic energy-level density formulation for rigid rotor-harmonic oscillator systems is validated against the well-studied CO+O˙ H system. The approximate hindered rotor energy-level density corrections are validated against the well-studied H2O2 system. The presented analytic energy-level density formulation gives a basis for developing novel numerical simulation schemes for chemical processes.

  2. Organic semiconductor density of states controls the energy level alignment at electrode interfaces

    PubMed Central

    Oehzelt, Martin; Koch, Norbert; Heimel, Georg

    2014-01-01

    Minimizing charge carrier injection barriers and extraction losses at interfaces between organic semiconductors and metallic electrodes is critical for optimizing the performance of organic (opto-) electronic devices. Here, we implement a detailed electrostatic model, capable of reproducing the alignment between the electrode Fermi energy and the transport states in the organic semiconductor both qualitatively and quantitatively. Covering the full phenomenological range of interfacial energy level alignment regimes within a single, consistent framework and continuously connecting the limiting cases described by previously proposed models allows us to resolve conflicting views in the literature. Our results highlight the density of states in the organic semiconductor as a key factor. Its shape and, in particular, the energy distribution of electronic states tailing into the fundamental gap is found to determine both the minimum value of practically achievable injection barriers as well as their spatial profile, ranging from abrupt interface dipoles to extended band-bending regions. PMID:24938867

  3. 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

  4. 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

    2015-04-01

    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

  5. Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

    PubMed

    Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

    2016-04-26

    We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces.

  6. Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations

    SciTech Connect

    Jin, Chengjun; Markussen, Troels; Thygesen, Kristian S.; Strange, Mikkel; Solomon, Gemma C.

    2013-11-14

    We study the effect of functional groups (CH{sub 3}*4, OCH{sub 3}, CH{sub 3}, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group.

  7. Energy levels and redox properties of aqueous Mn(2+/3+) from photoemission spectroscopy and density functional molecular dynamics simulation.

    PubMed

    Moens, Jan; Seidel, Robert; Geerlings, Paul; Faubel, Manfred; Winter, Bernd; Blumberger, Jochen

    2010-07-22

    Energy-resolved photoemission spectroscopy and density functional molecular dynamics simulations are combined to construct an energy level diagram for the Mn(2+/3+) redox reaction in aqueous solution. Two peaks centered at 8.88 and 10.26 eV electron binding energies can be assigned to the Mn2+ hexa-aquo complex with a peak area ratio of 2:2.83. Using the notation of crystal field theory, the peak at lower energies can be interpreted as arising from ionization from the e(g) levels (highest occupied molecular orbital, HOMO), and the peak at higher energies are from ionization of the t(2g) levels. The difference corresponds to the average crystal field splitting, 1.38 eV. From the position of the HOMO level and the absolute redox potential, an experimental value for the reorganization free energy of the aqueous Mn3+ hexa-aquo complex is estimated to be 2.98 eV. Density functional molecular dynamics simulations can reproduce the experimental vertical ionization energy, redox free energy, and reorganization free energies fairly well, provided that the absolute potential shift in periodic boundary conditions, finite size effects, and inaccuracies of the exchange correlation functional are taken into account. Most strikingly, in the simulations, we observe spontaneous and reversible deprotonation of the aqueous Mn3+ hexa-aquo complex to form MnOH(H2O)5(2+) + H+, in line with the low experimental pKa value of this ion. The interconversion between protonation states leads to interesting redox phenomena for aqueous Mn3+, culminating in a bimodal thermal distribution of the electron affinity.

  8. Carrier Density and Compensation in Semiconductors with Multi Dopants and Multi Transition Energy Levels: The Case of Cu Impurity in CdTe: Preprint

    SciTech Connect

    Wei, S. H.; Ma, J.; Gessert, T. A.; Chin, K. K.

    2011-07-01

    Doping is one of the most important issues in semiconductor physics. The charge carrier generated by doping can profoundly change the properties of semiconductors and their performance in optoelectronic device applications, such as solar cells. Using detailed balance theory and first-principles calculated defect formation energies and transition energy levels, we derive general formulae to calculate carrier density for semiconductors with multi dopants and multi transition energy levels. As an example, we studied CdTe doped with Cu, in which VCd, CuCd, and Cui are the dominant defects/impurities. We show that in this system, when Cu concentration increases, the doping properties of the system can change from a poor p-type, to a poorer p-type, to a better p-type, and then to a poor p-type again, in good agreement with experimental observation of CdTe-based solar cells.

  9. Theory of Energy Level Tuning in Quantum Dots by Surfactants

    NASA Astrophysics Data System (ADS)

    Zherebetskyy, Danylo; Wang, Lin-Wang; Materials Sciences Division, Lawrence Berkeley National Laboratory Team

    2015-03-01

    Besides quantum confinement that provides control of the quantum dot (QD) band gap, surface ligands allow control of the absolute energy levels. We theoretically investigate energy level tuning in PbS QD by surfactant exchange. We perform direct calculations of real-size QD with various surfactants within the frame of the density functional theory and explicitly analyze the influence of the surfactants on the electronic properties of the QD. This work provides a hint for predictable control of the absolute energy levels and their fine tuning within 3 eV range by modification of big and small surfactants that simultaneously passivate the QD surface.

  10. Temperature dependent energy levels of methylammonium lead iodide perovskite

    SciTech Connect

    Foley, Benjamin J.; Marlowe, Daniel L.; Choi, Joshua J. E-mail: mgupta@virginia.edu; Sun, Keye; Gupta, Mool C. E-mail: mgupta@virginia.edu; Saidi, Wissam A.; Scudiero, Louis E-mail: mgupta@virginia.edu

    2015-06-15

    Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

  11. Energy level transitions of gas in a 2D nanopore

    SciTech Connect

    Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.

    2015-10-27

    An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.

  12. Energy Levels of Hydrogen and Deuterium

    National Institute of Standards and Technology Data Gateway

    SRD 142 Energy Levels of Hydrogen and Deuterium (Web, free access)   This database provides theoretical values of energy levels of hydrogen and deuterium for principle quantum numbers n = 1 to 200 and all allowed orbital angular momenta l and total angular momenta j. The values are based on current knowledge of the revelant theoretical contributions including relativistic, quantum electrodynamic, recoil, and nuclear size effects.

  13. Energy levels for F-16 (Fluorine-16)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of Subvolume C `Tables of Excitations of Proton- and Neutron-rich Unstable Nuclei' of Volume 19 `Nuclear States from Charged Particle Reactions' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides energy levels for atomic nuclei of the isotope F-16 (fluorine, atomic number Z = 9, mass number A = 16).

  14. Defect energy levels from current transient recording

    NASA Astrophysics Data System (ADS)

    Momayezi, Michael

    1991-07-01

    Silicon detectors are widely used in high energy physics in vertexing and calorimetry applications. The radiative environment will introduce defects with energy levels in the bandgap into the crystals. At the high levels of radiation present at proton accelerators the defect concentration will easily approach or exceed the doping concentration of the usual high ohmic material. DLTS, the most common technique for defect characterization is known to fail under these conditions. To study heavy radiation damage in silicon detectors a new method has been developed. Using a DLTS-like pulser setup, the current transient from trap emptying is recorded on a fast digital scope being read out by a microcomputer. This is repeatedly done during a temperature scan. The time integral of the current transient equals the number of traps present and the activation enthalpy is found from the temperature dependence of the emission life time. If there is more than one energy level present the individual components may be extracted by a fitting procedure from the then multiexponential current transient. The sensitivity reached so far is, noise and systematics considered, ˜10 9 traps. Lifetimes between 5 μs and 5 ms are covered.

  15. Energy-level alignment at organic heterointerfaces

    PubMed Central

    Oehzelt, Martin; Akaike, Kouki; Koch, Norbert; Heimel, Georg

    2015-01-01

    Today’s champion organic (opto-)electronic devices comprise an ever-increasing number of different organic-semiconductor layers. The functionality of these complex heterostructures largely derives from the relative alignment of the frontier molecular-orbital energies in each layer with respect to those in all others. Despite the technological relevance of the energy-level alignment at organic heterointerfaces, and despite continued scientific interest, a reliable model that can quantitatively predict the full range of phenomena observed at such interfaces is notably absent. We identify the limitations of previous attempts to formulate such a model and highlight inconsistencies in the interpretation of the experimental data they were based on. We then develop a theoretical framework, which we demonstrate to accurately reproduce experiment. Applying this theory, a comprehensive overview of all possible energy-level alignment scenarios that can be encountered at organic heterojunctions is finally given. These results will help focus future efforts on developing functional organic interfaces for superior device performance. PMID:26702447

  16. Automated drawing system of quantum energy levels

    NASA Astrophysics Data System (ADS)

    Stampoultzis, M.; Sinatkas, J.; Tsakstara, V.; Kosmas, T. S.

    2014-03-01

    The purpose of this work is to derive an automated system that provides advantageous drawings of energy spectra for quantum systems (nuclei, atoms, molecules, etc.) required in various physical sciences. The automation involves the development of appropriate computational code and graphical imaging system based on raw data insertion, theoretical calculations and experimental or bibliographic data insertion. The system determines the appropriate scale to depict graphically with the best possible way in the available space. The presently developed code operates locally and the results are displayed on the screen and can be exported to a PostScript file. We note its main features to arrange and visualize in the available space the energy levels with their identity, taking care the existence in the final diagram the least auxiliary deviations. Future improvements can be the use of Java and the availability on the Internet. The work involves the automated plotting of energy levels in molecules, atoms, nuclei and other types of quantized energy spectra. The automation involves the development of an appropriate computational code and graphical imaging system.

  17. Energy level modification in lead sulfide quantum dot thin films through ligand exchange.

    PubMed

    Brown, Patrick R; Kim, Donghun; Lunt, Richard R; Zhao, Ni; Bawendi, Moungi G; Grossman, Jeffrey C; Bulović, Vladimir

    2014-06-24

    The electronic properties of colloidal quantum dots (QDs) are critically dependent on both QD size and surface chemistry. Modification of quantum confinement provides control of the QD bandgap, while ligand-induced surface dipoles present a hitherto underutilized means of control over the absolute energy levels of QDs within electronic devices. Here, we show that the energy levels of lead sulfide QDs, measured by ultraviolet photoelectron spectroscopy, shift by up to 0.9 eV between different chemical ligand treatments. The directions of these energy shifts match the results of atomistic density functional theory simulations and scale with the ligand dipole moment. Trends in the performance of photovoltaic devices employing ligand-modified QD films are consistent with the measured energy level shifts. These results identify surface-chemistry-mediated energy level shifts as a means of predictably controlling the electronic properties of colloidal QD films and as a versatile adjustable parameter in the performance optimization of QD optoelectronic devices.

  18. "Piekara's Chair": Mechanical Model for Atomic Energy Levels.

    ERIC Educational Resources Information Center

    Golab-Meyer, Zofia

    1991-01-01

    Uses the teaching method of models or analogies, specifically the model called "Piekara's chair," to show how teaching classical mechanics can familiarize students with the notion of energy levels in atomic physics. (MDH)

  19. Housing Electrons: Relating Quantum Numbers, Energy Levels, and Electron Configurations.

    ERIC Educational Resources Information Center

    Garofalo, Anthony

    1997-01-01

    Presents an activity that combines the concepts of quantum numbers and probability locations, energy levels, and electron configurations in a concrete, hands-on way. Uses model houses constructed out of foam board and colored beads to represent electrons. (JRH)

  20. Calculation of Rydberg energy levels for the francium atom

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Zhong; Chu, Jin-Min

    2010-06-01

    Based on the weakest bound electron potential model theory, the Rydberg energy levels and quantum defects of the np2Po1/2 (n = 7-50) and np2Po3/2 (n = 7-50) spectrum series for the francium atom are calculated. The calculated results are in excellent agreement with the 48 measured levels, and 40 energy levels for highly excited states are predicted.

  1. Energy level realignment in weakly interacting donor-acceptor binary molecular networks.

    PubMed

    Zhong, Jian-Qiang; Qin, Xinming; Zhang, Jia-Lin; Kera, Satoshi; Ueno, Nobuo; Wee, Andrew Thye Shen; Yang, Jinlong; Chen, Wei

    2014-02-25

    Understanding the effect of intermolecular and molecule-substrate interactions on molecular electronic states is key to revealing the energy level alignment mechanism at organic-organic heterojunctions or organic-inorganic interfaces. In this paper, we investigate the energy level alignment mechanism in weakly interacting donor-acceptor binary molecular superstructures, comprising copper hexadecafluorophthalocyanine (F16CuPc) intermixed with copper phthalocyanine (CuPc), or manganese phthalocynine (MnPc) on graphite. The molecular electronic structures have been systematically studied by in situ ultraviolet photoelectron spectroscopy (UPS) and low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS) experiments and corroborated by density functional theory (DFT) calculations. As demonstrated by the UPS and LT-STM/STS measurements, the observed unusual energy level realignment (i.e., a large downward shift in donor HOMO level and a corresponding small upward shift in acceptor HOMO level) in the CuPc-F16CuPc binary superstructures originates from the balance between intermolecular and molecule-substrate interactions. The enhanced intermolecular interactions through the hydrogen bonding between neighboring CuPc and F16CuPc can stabilize the binary superstructures and modify the local molecular electronic states. The obvious molecular energy level shift was explained by gap-state-mediated interfacial charge transfer. PMID:24433044

  2. Calibration of Electric Field Induced Energy Level Shifts in Argon

    NASA Astrophysics Data System (ADS)

    Hebner, Greg

    1999-10-01

    Argon is a commonly used gas in a number of discharges. As such it is an ideal candidate for spectroscopic based electric field measurements within the sheath and bulk discharge regions. Recently, measurements demonstrated the use of the Stark induced shifts of high lying energy levels in Argon to make spatially and temporally resolved electric field measurements [1]. However, that method relied on the cross calibration of known and calculable shifts in helium discharges to calibrate, in-situ, the energy level shifts in Argon. This poster shows the use of an atomic beam system to calibrate the electric field induced shift of high lying energy levels directly. In addition, data on very high lying argon levels, up to the 20 F manifold, were obtained. Comparison of our electric field induced energy level shift calibration curves with previous work will be shown. The possibility of using this system to calibrate energy level shifts in other gases of technological interest to the microelectronics and lighting industry will be discussed. [1]. J. B. Kim, K. Kawamura, Y. W. Choi, M. D. Bowden, K. Muraoka and V. Helbig, IEEE Transactions on Plasma Science, 26(5), 1556 (1998). This work was performed at Sandia National Laboratories and supported by the United States Department of Energy (DE-AC04-94AL85000).

  3. First-principles approach to calculating energy level alignment at aqueous semiconductor interfaces

    DOE PAGESBeta

    Kharche, Neerav; Muckerman, James T.; Hybertsen, Mark S.

    2014-10-21

    A first-principles approach is demonstrated for calculating the relationship between an aqueous semiconductor interface structure and energy level alignment. The physical interface structure is sampled using density functional theory based molecular dynamics, yielding the interface electrostatic dipole. The GW approach from many-body perturbation theory is used to place the electronic band edge energies of the semiconductor relative to the occupied 1b₁ energy level in water. The application to the specific cases of nonpolar (101¯0 ) facets of GaN and ZnO reveals a significant role for the structural motifs at the interface, including the degree of interface water dissociation and themore » dynamical fluctuations in the interface Zn-O and O-H bond orientations. As a result, these effects contribute up to 0.5 eV.« less

  4. First-principles approach to calculating energy level alignment at aqueous semiconductor interfaces

    SciTech Connect

    Kharche, Neerav; Muckerman, James T.; Hybertsen, Mark S.

    2014-10-21

    A first-principles approach is demonstrated for calculating the relationship between an aqueous semiconductor interface structure and energy level alignment. The physical interface structure is sampled using density functional theory based molecular dynamics, yielding the interface electrostatic dipole. The GW approach from many-body perturbation theory is used to place the electronic band edge energies of the semiconductor relative to the occupied 1benergy level in water. The application to the specific cases of nonpolar (101¯0 ) facets of GaN and ZnO reveals a significant role for the structural motifs at the interface, including the degree of interface water dissociation and the dynamical fluctuations in the interface Zn-O and O-H bond orientations. As a result, these effects contribute up to 0.5 eV.

  5. Efficiencies of thermodynamics when temperature-dependent energy levels exist.

    PubMed

    Yamano, Takuya

    2016-03-14

    Based on a generalized form of the second law of thermodynamics, in which the temperature-dependent energy levels of a system are appropriately included in entropy generation, we show that the effect reasonably appears in efficiencies of thermodynamic processes. PMID:26890276

  6. Degeneracy of energy levels of pseudo-Gaussian oscillators

    SciTech Connect

    Iacob, Theodor-Felix; Iacob, Felix; Lute, Marina

    2015-12-07

    We study the main features of the isotropic radial pseudo-Gaussian oscillators spectral properties. This study is made upon the energy levels degeneracy with respect to orbital angular momentum quantum number. In a previous work [6] we have shown that the pseudo-Gaussian oscillators belong to the class of quasi-exactly solvable models and an exact solution has been found.

  7. Energy Level Alignment at Aqueous GaN and ZnO Interfaces

    NASA Astrophysics Data System (ADS)

    Hybertsen, Mark S.; Kharche, Neerav; Muckerman, James T.

    2014-03-01

    Electronic energy level alignment at semiconductor-electrolyte interfaces is fundamental to electrochemical activity. Motivated in particular by the search for new materials that can be more efficient for photocatalysis, we develop a first principles method to calculate this alignment at aqueous interfaces and demonstrate it for the specific case of non-polar GaN and ZnO interfaces with water. In the first step, density functional theory (DFT) based molecular dynamics is used to sample the physical interface structure and to evaluate the electrostatic potential step at the interface. In the second step, the GW approach is used to evaluate the reference electronic energy level separately in the bulk semiconductor (valence band edge energy) and in bulk water (the 1b1 energy level), relative to the internal electrostatic energy reference. Use of the GW approach naturally corrects for errors inherent in the use of Kohn-Sham energy eigenvalues to approximate the electronic excitation energies in each material. With this predicted interface alignment, specific redox levels in water, with potentials known relative to the 1b1 level, can then be compared to the semiconductor band edge positions. Our results will be discussed in the context of experiments in which photoexcited GaN and ZnO drive the hydrogen evolution reaction. Research carried out at Brookhaven National Laboratory under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

  8. How to Draw Energy Level Diagrams in Excitonic Solar Cells.

    PubMed

    Zhu, X-Y

    2014-07-01

    Emerging photovoltaic devices based on molecular and nanomaterials are mostly excitonic in nature. The initial absorption of a photon in these materials creates an exciton that can subsequently dissociate in each material or at their interfaces to give charge carriers. Any attempt at mechanistic understanding of excitonic solar cells must start with drawing energy level diagrams. This seemingly elementary exercise, which is described in textbooks for inorganic solar cells, has turned out to be a difficult subject in the literature. The problem stems from conceptual confusion of single-particle energy with quasi-particle energy and the misleading practice of mixing the two on the same energy level diagram. Here, I discuss how to draw physically accurate energy diagrams in excitonic solar cells using only single-particle energies (ionization potentials and electron affinities) of both ground and optically excited states. I will briefly discuss current understanding on the electronic energy landscape responsible for efficient charge separation in excitonic solar cells.

  9. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    NASA Astrophysics Data System (ADS)

    Andreici, Emiliana-Laura; Petkova, Petya; Avram, Nicolae M.

    2015-12-01

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr2+ system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  10. Energy levels, lifetimes and radiative data of Ba XXVI

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Sharma, Rinku; Mohan, Man

    2016-05-01

    We report an extensive and an elaborate theoretical study of atomic data for Ba XXVI by considering Singlet, Doublet and Triplet (SDT) electron excitations within N-shell and single excitations from N-shell to O-shell. We have calculated energy levels and lifetimes for lowest 110 fine structure levels by using Multi-configuration Dirac-Fock method (MCDF). We have also considered Quantum Electrodynamics (QED) and Breit corrections in our calculations. We have presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions among lowest 110 levels. We have made comparisons of our calculated excitation energies and EUV (Extreme Ultraviolet) transition wavelengths with experimentally observed energy levels and wavelengths and achieved good agreement. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code (FAC). Additionally, we have provided new atomic data for Ba XXVI which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

  11. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    SciTech Connect

    Andreici, Emiliana-Laura; Petkova, Petya; Avram, Nicolae M.

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  12. a New Method for Solving the Z > 137 Problem and for Determination of Energy Levels of Hydrogen-Like Atoms

    NASA Astrophysics Data System (ADS)

    Neznamov, V. P.; Safronov, I. I.

    The "catastrophe" in solving the Dirac equation for an electron in the field of a point electric charge, which emerges for the charge numbers Z > 137, is removed in this work by new method of accounting of finite dimensions of nuclei. For this purpose, in numerical solutions of equations for Dirac radial wave functions, we introduce a boundary condition at the nucleus boundary such that the components of the electron current density is zero. As a result, for all nuclei of the periodic table the calculated energy levels practically coincide with the energy levels in standard solutions of the Dirac equation in the external field of the Coulomb potential of a point charge. Further, for Z > 105, the calculated energy level functions E(Z) are monotone and smooth. The lower energy level reaches the energy E = -mc2 (the electron "drop" on a nuclei) at Zc = 178. The proposed method of accounting of the finite size of nuclei can be easily used in numerical calculations of energy levels of many-electron atoms.

  13. Energy levels of double triangular graphene quantum dots

    SciTech Connect

    Liang, F. X.; Jiang, Z. T. Zhang, H. Y.; Li, S.; Lv, Z. T.

    2014-09-28

    We investigate theoretically the energy levels of the coupled double triangular graphene quantum dots (GQDs) based on the tight-binding Hamiltonian model. The double GQDs including the ZZ-type, ZA-type, and AA-type GQDs with the two GQDs having the zigzag or armchair boundaries can be coupled together via different interdot connections, such as the direct coupling, the chains of benzene rings, and those of carbon atoms. It is shown that the energy spectrum of the coupled double GQDs is the amalgamation of those spectra of the corresponding two isolated GQDs with the modification triggered by the interdot connections. The interdot connection is inclined to lift up the degeneracies of the energy levels in different degree, and as the connection changes from the direct coupling to the long chains, the removal of energy degeneracies is suppressed in ZZ-type and AA-type double GQDs, which indicates that the two coupled GQDs are inclined to become decoupled. Then we consider the influences on the spectra of the coupled double GQDs induced by the electric fields applied on the GQDs or the connection, which manifests as the global spectrum redistribution or the local energy level shift. Finally, we study the symmetrical and asymmetrical energy spectra of the double GQDs caused by the substrates supporting the two GQDs, clearly demonstrating how the substrates affect the double GQDs' spectrum. This research elucidates the energy spectra of the coupled double GQDs, as well as the mechanics of manipulating them by the electric field and the substrates, which would be a significant reference for designing GQD-based devices.

  14. Accurate energy levels for singly ionized platinum (Pt II)

    NASA Technical Reports Server (NTRS)

    Reader, Joseph; Acquista, Nicolo; Sansonetti, Craig J.; Engleman, Rolf, Jr.

    1988-01-01

    New observations of the spectrum of Pt II have been made with hollow-cathode lamps. The region from 1032 to 4101 A was observed photographically with a 10.7-m normal-incidence spectrograph. The region from 2245 to 5223 A was observed with a Fourier-transform spectrometer. Wavelength measurements were made for 558 lines. The uncertainties vary from 0.0005 to 0.004 A. From these measurements and three parity-forbidden transitions in the infrared, accurate values were determined for 28 even and 72 odd energy levels of Pt II.

  15. Energy level control: toward an efficient hot electron transport

    NASA Astrophysics Data System (ADS)

    Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu

    2014-08-01

    Highly efficient hot electron transport represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot electron capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the `excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot electron transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot electron/hole transport efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.

  16. Energy level control: toward an efficient hot electron transport.

    PubMed

    Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu

    2014-08-07

    Highly efficient hot electron transport represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot electron capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the 'excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot electron transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot electron/hole transport efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.

  17. Calculation of Electrochemical Energy Levels in Water Using the Random Phase Approximation and a Double Hybrid Functional.

    PubMed

    Cheng, Jun; VandeVondele, Joost

    2016-02-26

    Understanding charge transfer at electrochemical interfaces requires consistent treatment of electronic energy levels in solids and in water at the same level of the electronic structure theory. Using density-functional-theory-based molecular dynamics and thermodynamic integration, the free energy levels of six redox couples in water are calculated at the level of the random phase approximation and a double hybrid density functional. The redox levels, together with the water band positions, are aligned against a computational standard hydrogen electrode, allowing for critical analysis of errors compared to the experiment. It is encouraging that both methods offer a good description of the electronic structures of the solutes and water, showing promise for a full treatment of electrochemical interfaces.

  18. Energy levels of exciton in a gapped graphene sheet

    NASA Astrophysics Data System (ADS)

    Fallah, Farhang; Esmaeilzadeh, Mahdi

    2013-08-01

    A theory is presented for exciton formation in a graphene sheet using the center-of-mass approximation. The energy levels and wavefunctions of exciton are calculated analytically which show that the exciton can form if the band gap of graphene is not zero. We show that the energy gap of graphene plays the role of the mass which if not zero, leads to formation of the excitons. It is shown that the main quantum number of the exciton ground state changes with the graphene dielectric constant. Also, all of the states are found to be four-fold degenerate. The binding energy of exciton can reach as high as 1/4 of the energy gap of graphene which is notable among the conventional quasi-2D systems. This result can play an important rule in the photonics of graphene.

  19. Energy levels and radiative rates for transitions in Ga XXIV

    SciTech Connect

    El-Sayed, Fatma

    2012-07-15

    Energy levels, transition probabilities, oscillator strengths, line strengths, and lifetimes have been calculated for Oxygen-like Gallium, Ga XXIV. The configurations 2s{sup 2}2p{sup 4}, 2s2p{sup 5}, 2p{sup 6}, 2s2p{sup 4}3 Script-Small-L , 2s{sup 2}2p{sup 3}3 Script-Small-L , and 2p{sup 5}3 Script-Small-L were used in calculations and 226 fine-structure levels were obtained. The fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 226 levels of Ga XXIV, belonging to the n{<=}3 configurations. Comparisons have been made with earlier available theoretical and experimental results.

  20. Non-chiral 2d CFT with integer energy levels

    NASA Astrophysics Data System (ADS)

    Ashrafi, M.; Loran, F.

    2016-09-01

    The partition function of 2d conformal field theory is a modular invariant function. It is known that the partition function of a holomorphic CFT whose central charge is a multiple of 24 is a polynomial in the Klein function. In this paper, by using the medium temperature expansion we show that every modular invariant partition function can be mapped to a holomorphic partition function whose structure can be determined similarly. We use this map to study partition function of CFTs with half-integer left and right conformal weights. We show that the corresponding left and right central charges are necessarily multiples of 4. Furthermore, the degree of degeneracy of high-energy levels can be uniquely determined in terms of the degeneracy in the low energy states.

  1. Origin of the energy level alignment at organic/organic interfaces: The role of structural defects

    NASA Astrophysics Data System (ADS)

    Bussolotti, Fabio; Yang, Jinpeng; Hinderhofer, Alexander; Huang, Yuli; Chen, Wei; Kera, Satoshi; Wee, Andrew T. S.; Ueno, Nobuo

    2014-03-01

    In this paper, the electronic properties of as-deposited and N2-exposedCuPc/F16CuPc interface, a prototype system for organic photovoltaic applications, are investigated by using ultralow background, high-sensitivity photoemission spectroscopy. It is found that (i) N2 exposure significantly modifies the energy level alignment (ELA) at the interface between CuPc and F16CuPc layer and (ii) the direction of the N2-induced energy level shift of the CuPc depends on the position of the Fermi level (EF) in the CuPc highest occupied molecular orbital-lowest unoccupied molecular orbital gap of the as-deposited film. These observations are related to the changes in the density of gap states (DOGS) produced by structural imperfections in the molecular packing geometry, as introduced by the N2 penetration into the CuPc layer. This result demonstrates the key role of structure-induced DOGS in controlling the ELA at organic/organic interfaces.

  2. Energy level alignment at hybridized organic-metal interfaces from a GW projection approach

    NASA Astrophysics Data System (ADS)

    Chen, Yifeng; Tamblyn, Isaac; Quek, Su Ying

    Energy level alignments at organic-metal interfaces are of profound importance in numerous (opto)electronic applications. Standard density functional theory (DFT) calculations generally give incorrect energy level alignments and missing long-range polarization effects. Previous efforts to address this problem using the many-electron GW method have focused on physisorbed systems where hybridization effects are insignificant. Here, we use state-of-the-art GW methods to predict the level alignment at the amine-Au interface, where molecular levels do hybridize with metallic states. This non-trivial hybridization implies that DFT result is a poor approximation to the quasiparticle states. However, we find that the self-energy operator is approximately diagonal in the molecular basis, allowing us to use a projection approach to predict the level alignments. Our results indicate that the metallic substrate reduces the HOMO-LUMO gap by 3.5 4.0 eV, depending on the molecular coverage/presence of Au adatoms. Our GW results are further compared with those of a simple image charge model that describes the level alignment in physisorbed systems. Syq and YC acknowledge Grant NRF-NRFF2013-07 and the medium-sized centre program from the National Research Foundation, Singapore.

  3. Ideal Energy-Level Alignment at the ZnO/P3HT Photovoltaic Interface

    NASA Astrophysics Data System (ADS)

    Noori, Keian; Giustino, Feliciano

    2013-03-01

    Despite the significant progress made during the past decade, hybrid organic-inorganic photovoltaic devices comprising P3HT and ZnO still suffer from low short-circuit currents and moderate open-circuit voltages. These barriers call for a detailed examination of the atomic-scale physics underlying the energy-level alignment at the ZnO/P3HT interface, which is of critical importance if we are to understand what is the maximum ideal open-circuit voltage for this class of solar cell. Here we present the results of a first-principles study on large model interfaces between ZnO and P3HT. Using a combination of density-functional theory (DFT) and post-DFT methods based on hybrid functionals, we analyze the atomic structure and energetics of the semiconductor/polymer interface, as well as the interfacial energy-level alignment. We explore the effect of charge transfer on the ideal open-circuit voltage and identify a failure in the standard electron affinity rule. We determine a maximum ideal open-circuit voltage of ~2 V, which suggests that there is significant room for enhancing the performance of ZnO/P3HT solar cells by optimizing the interface at the nanoscale. This work is supported by the ERC under the EU FP7 / ERC grant no. 239578. Calculations were performed in part at the Oxford Supercomputing Centre.

  4. Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning

    PubMed Central

    Schlesinger, R.; Bianchi, F.; Blumstengel, S.; Christodoulou, C.; Ovsyannikov, R.; Kobin, B.; Moudgil, K.; Barlow, S.; Hecht, S.; Marder, S.R.; Henneberger, F.; Koch, N.

    2015-01-01

    The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach. PMID:25872919

  5. Interaction Determined Electron Energy Levels in One-Dimension

    NASA Astrophysics Data System (ADS)

    Pepper, Michael; Kumar, Sanjeev; Thomas, Kalarikad; Smith, Luke; Creeth, Graham; Farrer, Ian; Ritchie, David; Jones, Geraint; Jonathan, Griffiths; UCL Collaboration; Cavendish Laboratory Collaboration

    2015-03-01

    We have investigated electron transport in a quasi-one dimensional electron gas in the GaAs-AlGaAs heterostructure designed so that the confinement potential can be progressively weakened. This causes the energy levels to decrease in energy relative to each other, however this decrease occurs at different rates, a feature attributed to the energy being determined by both confinement and the electron-electron repulsion which varies with the shape of the wavefunction. It is found that the initial ground state crosses the higher levels so resulting in missing plateaux of quantised conductance. A change in the nature of the ground state to a more extended form causes an increase in the capacitance between the confining gates and the electrons. Both crossings and anti-crossings of the levels are found and these will be discussed along with other consequences of the form of the level interactions. The effects of level crossing on the spin dependent 0.7 structure will be presented. Supported by EPSRC (UK).

  6. Sleep and brain energy levels: ATP changes during sleep.

    PubMed

    Dworak, Markus; McCarley, Robert W; Kim, Tae; Kalinchuk, Anna V; Basheer, Radhika

    2010-06-30

    Sleep is one of the most pervasive biological phenomena, but one whose function remains elusive. Although many theories of function, indirect evidence, and even common sense suggest sleep is needed for an increase in brain energy, brain energy levels have not been directly measured with modern technology. We here report that ATP levels, the energy currency of brain cells, show a surge in the initial hours of spontaneous sleep in wake-active but not in sleep-active brain regions of rat. The surge is dependent on sleep but not time of day, since preventing sleep by gentle handling of rats for 3 or 6 h also prevents the surge in ATP. A significant positive correlation was observed between the surge in ATP and EEG non-rapid eye movement delta activity (0.5-4.5 Hz) during spontaneous sleep. Inducing sleep and delta activity by adenosine infusion into basal forebrain during the normally active dark period also increases ATP. Together, these observations suggest that the surge in ATP occurs when the neuronal activity is reduced, as occurs during sleep. The levels of phosphorylated AMP-activated protein kinase (P-AMPK), well known for its role in cellular energy sensing and regulation, and ATP show reciprocal changes. P-AMPK levels are lower during the sleep-induced ATP surge than during wake or sleep deprivation. Together, these results suggest that sleep-induced surge in ATP and the decrease in P-AMPK levels set the stage for increased anabolic processes during sleep and provide insight into the molecular events leading to the restorative biosynthetic processes occurring during sleep.

  7. Energy levels and transition rates for helium-like ions with Z = 10-36

    NASA Astrophysics Data System (ADS)

    Si, R.; Guo, X. L.; Wang, K.; Li, S.; Yan, J.; Chen, C. Y.; Brage, T.; Zou, Y. M.

    2016-08-01

    Aims: Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods: The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results: We provide accurate energies for the lowest singly excited 70 levels among 1snl(n ≤ 6,l ≤ (n-1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln'l'(n' ≤ 6,l' ≤ (n'-1)) configurations of helium-like ions with Z = 10-36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions: Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics. Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A141

  8. First-Principles Approach to Energy Level Alignment at Aqueous Semiconductor Interfaces

    NASA Astrophysics Data System (ADS)

    Hybertsen, Mark

    2015-03-01

    We have developed a first principles method to calculate the energy level alignment between semiconductor band edges and reference energy levels at aqueous interfaces. This alignment is fundamental to understand the electrochemical characteristics of any semiconductor electrode in general and the potential for photocatalytic activity in particular. For example, in the search for new photo-catalytic materials, viable candidates must demonstrate both efficient absorption of the solar spectrum and an appropriate alignment of the band edge levels in the semiconductor to the redox levels for the target reactions. In our approach, the interface-specific contribution to the electrostatic step across the interface is evaluated using density functional theory (DFT) based molecular dynamics to sample the physical interface structure and the corresponding change in the electrostatic potential at the interface. The reference electronic levels in the semiconductor and in the water are calculated using the GW approach, which naturally corrects for errors inherent in the use of Kohn-Sham energy eigenvalues to approximate the electronic excitation energies in each material. Taken together, our calculations provide the alignment of the semiconductor valence band edge to the centroid of the highest occupied 1b1 level in water. The known relationship of the 1b1 level to the normal hydrogen electrode completes the connection to electrochemical levels. We discuss specific results for GaN, ZnO, and TiO2. The effect of interface structural motifs, such as different degrees of water dissociation, and of dynamical characteristics, will be presented together with available experimental data. Work supported by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-98CH10886.

  9. Quantum Monte Carlo : not just for energy levels.

    SciTech Connect

    Nollett, K. M.; Physics

    2007-01-01

    Quantum Monte Carlo and realistic interactions can provide well-motivated vertices and overlaps for DWBA analyses of reactions. Given an interaction in vaccum, there are several computational approaches to nuclear systems, as you have been hearing: No-core shell model with Lee-Suzuki or Bloch-Horowitz for Hamiltonian Coupled clusters with G-matrix interaction Density functional theory, granted an energy functional derived from the interaction Quantum Monte Carlo - Variational Monte Carlo Green's function Monte Carlo. The last two work directly with a bare interaction and bare operators and describe the wave function without expanding in basis functions, so they have rather different sets of advantages and disadvantages from the others. Variational Monte Carlo (VMC) is built on a sophisticated Ansatz for the wave function, built on shell model like structure modified by operator correlations. Green's function Monte Carlo (GFMC) uses an operator method to project the true ground state out of a reasonable guess wave function.

  10. Energy level shifts at the silica/Ru(0001) heterojunction driven by surface and interface dipoles

    DOE PAGESBeta

    Wang, Mengen; Zhong, Jian -Qiang; Kestell, John; Waluyo, Iradwikanari; Stacchiola, Dario J.; Boscoboinik, J. Anibal; Lu, Deyu

    2016-09-12

    Charge redistribution at heterogeneous interfaces is a fundamental aspect of surface chemistry. Manipulating the amount of charges and the magnitude of dipole moments at the interface in a controlled way has attracted tremendous attention for its potential to modify the activity of heterogeneous catalysts in catalyst design. Two-dimensional ultrathin silica films with well-defined atomic structures have been recently synthesized and proposed as model systems for heterogeneous catalysts studies. R. Wlodarczyk et al. (Phys. Rev. B, 85, 085403 (2012)) have demonstrated that the electronic structure of silica/Ru(0001) can be reversibly tuned by changing the amount of interfacial chemisorbed oxygen. Here wemore » carried out systematic investigations to understand the underlying mechanism through which the electronic structure at the silica/Ru(0001) interface can be tuned. As corroborated by both in situ X-ray photoelectron spectroscopy and density functional theory calculations, the observed interface energy level alignments strongly depend on the surface and interfacial charge transfer induced dipoles at the silica/Ru(0001) heterojunction. These observations may help to understand variations in catalytic performance of the model system from the viewpoint of the electronic properties at the confined space between the silica bilayer and the Ru(0001) surface. As a result, the same behavior is observed for the aluminosilicate bilayer, which has been previously proposed as a model system for zeolites.« less

  11. Dynamical image-charge effect in molecular tunnel junctions: Beyond energy level alignment

    NASA Astrophysics Data System (ADS)

    Jin, Chengjun; Thygesen, Kristian S.

    2014-01-01

    When an electron tunnels between two metal contacts it temporarily induces an image charge (IC) in the electrodes which acts back on the tunneling electron. It is usually assumed that the IC forms instantaneously such that a static model for the image potential applies. Here we investigate how the finite IC formation time affects charge transport through a molecule suspended between two electrodes. For a single-level model, an analytical treatment shows that the conductance is suppressed by a factor Z2, where Z is the quasiparticle renormalization factor, compared to the static IC approximation. We show that Z can be expressed either in terms of the plasma frequency of the electrode or as the overlap between electrode wave functions corresponding to an empty and filled level, respectively. First-principles GW calculations for benzene-diamine connected to gold electrodes show that the dynamical corrections can reduce the conductance by more than a factor of two when compared to static GW or density functional theory where the molecular energy levels have been shifted to match the exact quasiparticle levels.

  12. Energy Levels and the de Broglie Relationship for High School Students

    ERIC Educational Resources Information Center

    Gianino, Concetto

    2008-01-01

    In this article, four examples of possible lessons on energy levels for high school are described: a particle in a box, a finite square well, the hydrogen atom and a harmonic oscillator. The energy levels are deduced through the use of the steady-state condition and the de Broglie relationship. In particular, the harmonic oscillator energy levels…

  13. Ab-inito calculation of energy level alignment and vacuum level shift at CuPc/C60 interfaces

    NASA Astrophysics Data System (ADS)

    Sai, Na; Zhu, Xiaoyang; Chelikowsky, James; Leung, Kevin

    2012-02-01

    The alignment of the donor and acceptor enegy levels is of crucial importance for organic photovotaic performance. We investigate the interfaical electronic structure and energy level alignment of copper phthalocyanine (CuPc)/fullerene (C60) using ab-inito density functional theory calculations including van der Waals interactions and hybrid density functionals. We show that energy level alignment critically depends on the standing-up and lying-down orientation of the CuPc molecules relative to C60 at the interface. We calculate the magnitude of the interface dipole at different molecular orientations and compare them to the vacuum level shift observed in photoemission spectroscopy. The validity of existing theoretical models which invoke charge transfer on this organic interface will be discussed in light of our predictions. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Treatment of Electronic Energy Level Transition and Ionization Following the Particle-Based Chemistry Model

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Lewis, Mark

    2010-01-01

    A new method of treating electronic energy level transitions as well as linking ionization to electronic energy levels is proposed following the particle-based chemistry model of Bird. Although the use of electronic energy levels and ionization reactions in DSMC are not new ideas, the current method of selecting what level to transition to, how to reproduce transition rates, and the linking of the electronic energy levels to ionization are, to the author s knowledge, novel concepts. The resulting equilibrium temperatures are shown to remain constant, and the electronic energy level distributions are shown to reproduce the Boltzmann distribution. The electronic energy level transition rates and ionization rates due to electron impacts are shown to reproduce theoretical and measured rates. The rates due to heavy particle impacts, while not as favorable as the electron impact rates, compare favorably to values from the literature. Thus, these new extensions to the particle-based chemistry model of Bird provide an accurate method for predicting electronic energy level transition and ionization rates in gases.

  15. ENERGY LEVELS AND SPECTRAL LINES OF SINGLY IONIZED MANGANESE (Mn II)

    SciTech Connect

    Kramida, Alexander; Sansonetti, Jean E.

    2013-04-01

    This compilation revises the previously recommended list of energy levels of singly ionized manganese (Mn II) and provides a comprehensive list of observed spectral lines and transition probabilities in this spectrum. The new level optimization takes into account critically assessed uncertainties of measured wavelengths and includes about a hundred high-precision wavelengths determined by laser spectroscopy and Fourier transform techniques. Uncertainties of 63% of energy levels and 74% of Ritz wavelengths are reduced by a factor of three on average.

  16. New energy levels of atomic niobium by laser induced fluorescence spectroscopy in the near infrared

    NASA Astrophysics Data System (ADS)

    Öztürk, I. K.; Başar, Gö; Er, A.; Güzelçimen, F.; Başar, Gü; Kröger, S.

    2015-01-01

    Laser-induced fluorescence spectroscopy was applied in order to find new energy levels of the niobium atom. A continuous wave tuneable titanium-sapphire laser in the wavelength range from 750 to 865 nm and a hollow-cathode lamp were used. We discovered four energy levels of even parity, three lying levels below 19 000 cm-1 and one at much higher energy. Additionally hyperfine structure data of six levels of odd parity were determined.

  17. Berry{close_quote}s phase in the presence of a stochastically evolving environment: A geometric mechanism for energy-level broadening

    SciTech Connect

    Gaitan, F.

    1998-09-01

    The generic Berry phase scenario in which a two-level system is coupled to a second system whose dynamical coordinate is slowly varying is generalized to allow for stochastic evolution of the slow system. The stochastic behavior is produced by coupling the slow system to a heat reservoir, which is modeled by a bath of harmonic oscillators initially in equilibrium at temperature T, and whose spectral density has a bandwidth that is small compared to the energy-level spacing of the fast system. The well-known energy-level shifts produced by Berry{close_quote}s phase in the fast system, in conjunction with the stochastic motion of the slow system, leads to a broadening of the fast system energy levels. In the limit of strong damping and sufficiently low temperature, we determine the degree of level broadening analytically, and show that the slow system dynamics satisfies a Langevin equation in which Lorentz-like and electriclike forces appear as a consequence of geometrical effects. We also determine the average energy level shift produced in the fast system by this mechanism. {copyright} {ital 1998} {ital The American Physical Society}

  18. Improved discrimination in photographic density contouring

    NASA Technical Reports Server (NTRS)

    Godding, R. A.

    1974-01-01

    Density discrimination can be accomplished through use of special photographic contouring material which has two sensitive layers (one negative, one positive) on single support. Process will be of interest to investigators who require finer discrimination of densities of original photograph for purposes such as identification of crops and analysis of energy levels of radiating objects.

  19. Study of the crossing of quasi-energy levels in a four-level system

    SciTech Connect

    Arushanyan, S; Melikyan, A; Saakyan, S

    2011-05-31

    It was shown previously that in taking into account only dipole transitions, the crossing of quasi-energy levels is possible in the system if any of the transitions forms a closed loop. It followed herefrom that for the analysis of the crossing conditions, it is necessary to consider a system which has at least four levels. In this paper we show that we can uniquely specify which quasi-energy levels cross at the given values of the parameters of the atomic system and radiation field, without solving an algebraic quartic equation. It was found that the most suitable system for the implementation of the crossing is the group of energy levels {sup 5}S{sub 1/2}, {sup 5}P{sub 1/2}, {sup 5}P{sub 3/2} and {sup 5}D{sub 3/2} of a rubidium atom. The performed calculations of the laser field intensity and frequency values at which crossing takes place in this system show that they are easily attainable. It turned out that in this system there occur crossing of quasi-energy levels corresponding to the excited atomic levels. (intersection of quasi-energy levels)

  20. Energy levels of one-dimensional systems satisfying the minimal length uncertainty relation

    NASA Astrophysics Data System (ADS)

    Bernardo, Reginald Christian S.; Esguerra, Jose Perico H.

    2016-10-01

    The standard approach to calculating the energy levels for quantum systems satisfying the minimal length uncertainty relation is to solve an eigenvalue problem involving a fourth- or higher-order differential equation in quasiposition space. It is shown that the problem can be reformulated so that the energy levels of these systems can be obtained by solving only a second-order quasiposition eigenvalue equation. Through this formulation the energy levels are calculated for the following potentials: particle in a box, harmonic oscillator, Pöschl-Teller well, Gaussian well, and double-Gaussian well. For the particle in a box, the second-order quasiposition eigenvalue equation is a second-order differential equation with constant coefficients. For the harmonic oscillator, Pöschl-Teller well, Gaussian well, and double-Gaussian well, a method that involves using Wronskians has been used to solve the second-order quasiposition eigenvalue equation. It is observed for all of these quantum systems that the introduction of a nonzero minimal length uncertainty induces a positive shift in the energy levels. It is shown that the calculation of energy levels in systems satisfying the minimal length uncertainty relation is not limited to a small number of problems like particle in a box and the harmonic oscillator but can be extended to a wider class of problems involving potentials such as the Pöschl-Teller and Gaussian wells.

  1. Impact behaviour of Napier/polyester composites under different energy levels

    NASA Astrophysics Data System (ADS)

    Fahmi, I.; Majid, M. S. Abdul; Afendi, M.; Haslan, M.; Helmi E., A.; M. Haameem J., A.

    2016-07-01

    The effects of different energy levels on the impact behaviour of Napier fibre/polyester reinforced composites were investigated. Napier fibre was extracted using traditional water retting process to be utilized as reinforcing materials in polyester composite laminates. 25% fibre loading composite laminates were prepared and impacted at three different energy levels; 2.5,5 and 7.5 J using an instrumented drop weight impact testing machine (IMATEK IM10). The outcomes show that peak force and contact time increase with increased impact load. The energy absorption was then calculated from the force displacement curve. The results indicated that the energy absorption decreases with increasing energy levels of the impact. Impacted specimens were observed visually for fragmentation fracture using an optical camera to identify the failure mechanisms. Fracture fragmentation pattern from permanent dent to perforation with radial and circumferential was observed.

  2. Chemical control over the energy-level alignment in a two-terminal junction

    NASA Astrophysics Data System (ADS)

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-07-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.

  3. Chemical control over the energy-level alignment in a two-terminal junction.

    PubMed

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C S Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A

    2016-07-26

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.

  4. Chemical control over the energy-level alignment in a two-terminal junction.

    PubMed

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C S Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  5. Chemical control over the energy-level alignment in a two-terminal junction

    PubMed Central

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  6. Energy levels of odd-even nuclei using broken pair model

    NASA Astrophysics Data System (ADS)

    Hamammu, I. M.; Haq, S.; Eldahomi, J. M.

    2012-09-01

    A method to calculate energy levels and wave functions of odd-even nuclei, in the frame work of the broken pair model have been developed. The accuracy of the model has been tested by comparing the shell model results of limiting cases in which the broken pair model exactly coincides with the shell model, where there are two-proton/neutron + one-neutron/proton in the valence levels. The model is then applied to calculate the energy levels of some nuclei in the Zirconium region. The model results compare reasonably well with the shell model as well as with the experimental data.

  7. Inversion Vibrational Energy Levels of AsH3 + Studied by Zero-Kinetic Photoelectron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mo, Yuxiang

    2016-06-01

    The rotational-resolved vibrational spectra of AsH3 + have been measured for the first time with vibrational energies up to 6000 wn above the ground state using zero-kinetic energy photoelectron spectroscopic method. The inversion vibrational energy levels (νb{2}) and the corresponding rotational constants for the νb{2} =0-16 have been determined. The tunneling splittings of the inversion vibration energy levels have been observed for the ground and the first excited vibrational states. The geometric parameters of AsH3 + as a function of inversion vibrational quantum states have been determined, indicating that the geometric structure of the cation changes from near planar structure to a pyramidal structure with more vibrational excitations. In addition to the experimental measurement, a two-dimensional theoretical calculation including the two symmetric vibrational modes was performed to determine the energy levels of the symmetric inversion and As-H stretching vibrations. The calculated vibrational energy levels are in good agreement with the experimental results. The first adiabatic ionization energy (IE) for AsH3 was also accurately determined. The result of this work will be compared with our published result on the PH3+.

  8. Self-energy shift of the energy levels of atomic hydrogen in photonic crystal medium

    NASA Astrophysics Data System (ADS)

    Gainutdinov, R. Kh; Khamadeev, M. A.; Steryakov, O. V.; Ziyatdinova, K. A.; Salakhov, M. Kh

    2016-05-01

    Corrections to the average kinetic energy of atomic electrons caused by the change in electron mass in the photonic crystal medium are investigated. Corresponding shift of energy levels of atoms placed in a photonic crystal is shown to be of order of the ordinary Lamb shift.

  9. Probing Energy Levels of Large Array Quantum Dot Superlattice by Electronic Transport Measurement

    NASA Astrophysics Data System (ADS)

    Bisri, S. Z.; Degoli, E.; Spallanzani, N.; Krishnan, G.; Kooi, B.; Ghica, C.; Yarema, M.; Protesescu, L.; Heiss, W.; Kovalenko, M.; Pulci, O.; Ossicini, S.; Iwasa, Y.; Loi, M. A.

    2015-03-01

    Colloidal quantum dot superlattice (CQDS) emerges as new type of hybrid solids allowing easy fabrication of devices that exploits the quantum confinement properties of individual QD. This materials displays peculiar characters, making investigation of their transport properties nontrivial. Besides the bandgap variations, 0D nature of QD lead to the formation of discrete energy subbands. These subbands are crucial for multiple exciton generation (for efficient solar cell), thermoelectric material and multistate transistor. Full understanding of the CQDS energy level structure is vital to use them in complex devices. Here we show a powerful method to determine the CQDS electronic energy levels from their intrinsic charge transport characteristics. Via the use of ambipolar transistors with CQDS as active materials and gated using highly capacitive ionic liquid gating, Fermi energy can be largely tuned. It can access energy levels beyond QD's HOMO & LUMO. Ability to probe not only the bandgap, but also the discrete energy level from large assembly of QD at room temperature suggests the formation of energy minibands in this system.

  10. Energy Levels in Helium and Neon Atoms by an Electron-Impact Method.

    ERIC Educational Resources Information Center

    Taylor, N.; And Others

    1981-01-01

    Electronic energy levels in noble gas atoms may be determined with a simple teaching apparatus incorporating a resonance potentials tube in which the electron beam intensity is held constant. The resulting spectra are little inferior to those obtained by more elaborate electron-impact methods and complement optical emission spectra. (Author/SK)

  11. Peculiarities of collisional excitation transfer with excited screened energy levels of atoms

    SciTech Connect

    Gerasimov, V. A.; Gerasimov, V. V.; Pavlinskiy, A. V.

    2007-09-15

    We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

  12. A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Pérez, E.; Dueñas, S.; Castán, H.; García, H.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; Olea, J.; González-Díaz, G.

    2015-12-01

    The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (1013 cm-2 and 1014 cm-2) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around Ec-425 and Ec-275 meV for implantation doses of 1013 cm-2 and 1014 cm-2, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, Ec and Ec-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known, the Meyer-Neldel rule typically appears in processes involving multiple excitations, like

  13. A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

    SciTech Connect

    Pérez, E.; Dueñas, S.; Castán, H.; García, H.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G.; Olea, J.

    2015-12-28

    The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (10{sup 13 }cm{sup -2} and 10{sup 14 }cm{sup -2}) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around E{sub c}-425 and E{sub c}-275 meV for implantation doses of 10{sup 13 }cm{sup −2} and 10{sup 14 }cm{sup −2}, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, E{sub c} and E{sub c}-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known

  14. A system for measuring thermal activation energy levels in silicon by thermally stimulated capacitance

    NASA Technical Reports Server (NTRS)

    Cockrum, R. H.

    1982-01-01

    One method being used to determine energy level(s) and electrical activity of impurities in silicon is described. The method is called capacitance transient spectroscopy (CTS). It can be classified into three basic categories: the thermally stimulated capacitance method, the voltage-stimulated capacitance method, and the light-stimulated capacitance method; the first two categories are discussed. From the total change in capacitance and the time constant of the capacitance response, emission rates, energy levels, and trap concentrations can be determined. A major advantage of using CTS is its ability to detect the presence of electrically active impurities that are invisible to other techniques, such as Zeeman effect atomic absorption, and the ability to detect more than one electrically active impurity in a sample. Examples of detection of majority and minority carrier traps from gold donor and acceptor centers in silicon using the capacitance transient spectrometer are given to illustrate the method and its sensitivity.

  15. Variational Calculations of Ro-Vibrational Energy Levels and Transition Intensities for Tetratomic Molecules

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    A description is given of an algorithm for computing ro-vibrational energy levels for tetratomic molecules. The expressions required for evaluating transition intensities are also given. The variational principle is used to determine the energy levels and the kinetic energy operator is simple and evaluated exactly. The computational procedure is split up into the determination of one dimensional radial basis functions, the computation of a contracted rotational-bending basis, followed by a final variational step coupling all degrees of freedom. An angular basis is proposed whereby the rotational-bending contraction takes place in three steps. Angular matrix elements of the potential are evaluated by expansion in terms of a suitable basis and the angular integrals are given in a factorized form which simplifies their evaluation. The basis functions in the final variational step have the full permutation symmetries of the identical particles. Sample results are given for HCCH and BH3.

  16. Quasipotential equation for hydrogen isotopes. Muonic atoms. Ground state energy levels

    NASA Astrophysics Data System (ADS)

    Bakalov, D.

    1980-06-01

    The quasipotential for the electromagnetic interaction of two particles of spin {1}/{2} or 1 with arbitrary electromagnetic interaction of two particles of spin {1}/{2} or 1 with arbitrary electromagnetic structure is constructed in the one-photon approximation. Todorov's quasipotential equation is applied to calculate the ground state energy levels of the muonic atoms pμ, dμ and tμ with accuracy 10 -3 eV.

  17. Calculations of energy levels and lifetimes of low-lying states of barium and radium

    SciTech Connect

    Dzuba, V. A.; Ginges, J. S. M.

    2006-03-15

    We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.

  18. Energy level formula for the Morse oscillator with an additional kinetic coupling potential

    NASA Astrophysics Data System (ADS)

    Fan, Hong-yi; Chen, Bo-zhan; Fan, Yue

    1996-02-01

    Based on the <η| representation which is the common eigenstate of the relative position x1 - x2 and the total momentum P1 + P2 of two particles we derive the energy level formula for a Morse oscillator with an additional kinetic coupling potential. The <η| representation seems to provide a direct and convenient approach for solving certain dynamical problems for two-body systems.

  19. Effect of a metallic gate on the energy levels of a shallow donor

    SciTech Connect

    Slachmuylders, A. F.; Partoens, B.; Peeters, F. M.; Magnus, W.

    2008-02-25

    We have investigated the effect of a metallic gate on the bound states of a shallow donor located near the gate. We calculate the energy spectrum as a function of the distance between the metallic gate and the donor and find an anticrossing behavior in the energy levels for certain distances. We show how a transverse electric field can tune the average position of the electron with respect to the metallic gate and the impurity.

  20. Energy level alignment of single-wall carbon nanotubes on metal surfaces

    NASA Astrophysics Data System (ADS)

    Clair, Sylvain; Kim, Yousoo; Kawai, Maki

    2011-06-01

    We studied the electronic configuration of single-wall carbon nanotubes adsorbed on well-defined Au(111) and Cu(111) surfaces. We found opposite behaviors for their energy-level alignment with metal: nanotubes are p-doped on Au(111) and n-doped on Cu(111). The doping level is not uniquely defined for a particular metal surface but rather exhibits a distribution depending on several uncontrolled factors such as nanotube geometry and adsorption configuration.

  1. Interfacial energy level bending in a crystalline p/p-type organic heterostructure

    SciTech Connect

    Zhu Feng; Grobosch, Mandy; Treske, Uwe; Knupfer, Martin; Huang Lizhen; Ji Shiliang; Yan Donghang

    2011-05-16

    A conduction channel was observed at the heterointerface of the crystalline p-type organic films copper phthalocyanine (CuPc) and 2,5-bis(4-biphenylyl) bithiophene (BP2T). Energy level bending at the interface is confirmed by photoemission spectroscopy, which verifies a charge transfer between CuPc and BP2T. This provides a further route to utilize interfacial electronic properties in functional devices and also documents the importance of reconsidering the interfacial electronic structure of organic heterostructures.

  2. Model for describing non-equilibrium helium plasma energy level population

    NASA Astrophysics Data System (ADS)

    Kavyrshin, D. I.; Chinnov, V. F.; Ageev, A. G.

    2015-11-01

    A new method for calculating the population of excited levels of helium atoms and ions is suggested. The method is based on direct solution of a system of balance equations for all energy levels for which it was possible to obtain process speed constants. The equations include terms for the processes of particle loss and income by excitation and deexcitation, ionization and recombination as well as losses due to diffusion and radiation. The challenge of solution of such large system is also discussed.

  3. Quantum cosmological Friedman models with a Yang-Mills field and positive energy levels

    NASA Astrophysics Data System (ADS)

    Gerhardt, Claus

    2010-02-01

    We prove the existence of a spectral resolution of the Wheeler-DeWitt equation when the matter field is provided by a Yang-Mills field, with or without mass term, if the spatial geometry of the underlying spacetime is homothetic to {\\bb R}^{3} . The energy levels of the resulting quantum model, i.e. the eigenvalues of the corresponding self-adjoint Hamiltonian with a pure point spectrum, are strictly positive. This work has been supported by the DFG.

  4. Control of Electronic Symmetry and Rectification through Energy Level Variations in Bilayer Molecular Junctions.

    PubMed

    Bayat, Akhtar; Lacroix, Jean-Christophe; McCreery, Richard L

    2016-09-21

    Two layers of molecular oligomers were deposited on flat carbon electrode surfaces by electrochemical reduction of diazonium reagents, then a top contact applied to complete a solid-state molecular junction containing a molecular bilayer. The structures and energy levels of the molecular layers included donor molecules with relatively high energy occupied orbitals and acceptors with low energy unoccupied orbitals. When the energy levels of the two molecular layers were similar, the device had electronic characteristics similar to a thick layer of a single molecule, but if the energy levels differed, the current voltage behavior exhibited pronounced rectification. Higher current was observed when the acceptor molecule was biased negatively in eight different bilayer combinations, and the direction of rectification was reversed if the molecular layers were also reversed. Rectification persisted at very low temperature (7 K), and was activationless between 7 and 100 K. The results are a clear example of a "molecular signature" in which electronic behavior is directly affected by molecular structure and orbital energies. The rectification mechanism is discussed, and may provide a basis for rational design of electronic properties by variation of molecular structure.

  5. by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination

    NASA Astrophysics Data System (ADS)

    Wang, Xia; Kou, Dong-Xing; Zhou, Wen-Hui; Zhou, Zheng-Ji; Wu, Si-Xin; Cao, Xuan

    2014-05-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S2- decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed.

  6. Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures

    PubMed Central

    Cochrane, K. A.; Schiffrin, A.; Roussy, T. S.; Capsoni, M.; Burke, S. A.

    2015-01-01

    Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials. PMID:26440933

  7. Energy levels and multipole transition properties of C4+ ion in Debye plasmas

    NASA Astrophysics Data System (ADS)

    Xie, L. Y.; Wang, J. G.; Janev, R. K.; Qu, Y. Z.; Dong, C. Z.

    2012-05-01

    Plasma screening effects on the energy structure and radiative transition properties of helium-like C4+ ions embedded in Debye plasmas are investigated by using the multi-configuration Dirac-Hartree-Fock method incorporating the Debye-Hückel potential for both the electron-nucleus and electron-electron interactions. Seventeen fine-structure energy levels of the low-lying 1 s 2, 1 s2 l( l = s,p) and 1 s3 l'( l' = s,p,d) configurations, as well as the electric-dipole ( E1), magnetic-dipole ( M1) and magnetic-quadrupole ( M2) transition probabilities and oscillator strengths between these levels have been calculated over a wide range of screening parameters. It is found that the plasma screening leads to a decrease of excitation energies and alters the energy levels remarkably. For Δn ≠ 0 transitions, the spontaneous decay spectra are red-shifted and their oscillator strengths and transition probabilities decrease with increasing the interaction screening, while those for the Δn = 0 transitions exhibit opposite patterns. The influence of electron-nucleus and electron-electron screened interactions on the changes of energy levels and transition properties are analyzed. Comparison is made of present results with other data available in the literature for this ion.

  8. Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures.

    PubMed

    Cochrane, K A; Schiffrin, A; Roussy, T S; Capsoni, M; Burke, S A

    2015-01-01

    Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials. PMID:26440933

  9. Energy level modification in lead sulfide quantum dot photovoltaics through ligand exchange

    NASA Astrophysics Data System (ADS)

    Brown, Patrick; Kim, Donghun; Lunt, Richard; Bawendi, Moungi; Grossman, Jeffrey; Bulovic, Vladimir

    2014-03-01

    The electronic properties of lead sulfide colloidal quantum dots (PbS QDs) can be controlled through modification of QD size and surface chemistry. Novel surface passivation techniques involving organic or inorganic ligands have contributed to a rapid rise in the efficiency of QD photovoltaics, yet the influence of ligand-induced surface dipoles on PbS QD energy levels and photovoltaic device operation is not yet completely understood. Here, the valence band energies of PbS QDs treated with twelve different ligands are measured using ultraviolet photoelectron spectroscopy (UPS), and a valence band shift of up to 0.75 eV is observed between different ligand treatments. Atomistic simulations of ligand binding to pristine PbS(100) and PbS(111) slabs qualitatively reproduce the measured energy level shifts. 1,2-benzenedithiol and 1,3-benzendithiol treatments, which result in valence band energies differing by ~ 0.2 eV, are employed for PbS QDs in three different solar cell architectures, and changes in device performance are correlated with the measured energy level shift. These findings complement the known bandgap-tunability of colloidal QDs and highlight an additional level of control over the electronic properties of PbS QDs.

  10. Control of Electronic Symmetry and Rectification through Energy Level Variations in Bilayer Molecular Junctions.

    PubMed

    Bayat, Akhtar; Lacroix, Jean-Christophe; McCreery, Richard L

    2016-09-21

    Two layers of molecular oligomers were deposited on flat carbon electrode surfaces by electrochemical reduction of diazonium reagents, then a top contact applied to complete a solid-state molecular junction containing a molecular bilayer. The structures and energy levels of the molecular layers included donor molecules with relatively high energy occupied orbitals and acceptors with low energy unoccupied orbitals. When the energy levels of the two molecular layers were similar, the device had electronic characteristics similar to a thick layer of a single molecule, but if the energy levels differed, the current voltage behavior exhibited pronounced rectification. Higher current was observed when the acceptor molecule was biased negatively in eight different bilayer combinations, and the direction of rectification was reversed if the molecular layers were also reversed. Rectification persisted at very low temperature (7 K), and was activationless between 7 and 100 K. The results are a clear example of a "molecular signature" in which electronic behavior is directly affected by molecular structure and orbital energies. The rectification mechanism is discussed, and may provide a basis for rational design of electronic properties by variation of molecular structure. PMID:27563739

  11. Effect of acidity on the energy level of curcumin dye extracted from Curcuma longa L.

    NASA Astrophysics Data System (ADS)

    Agustia, Yuda Virgantara; Suyitno, Arifin, Zainal; Sutanto, Bayu

    2016-03-01

    The purpose of this research is to investigate the effect of acidity on the energy level of curcumin dye. The natural dye, curcumin, was synthesized from Curcuma longa L. using a simple extraction technique. The purification of curcumin dye was conducted in a column of chromatography and its characteristics were studied. Next, the purified curcumin dye was added by benzoic acids until various acidities of 3.0, 3.5, 4.0, 4.5, and 5.0. The absorbance spectra and the functionality groups found in the dyes were detected by ultraviolet-visible spectroscopy and Fourier-transform infrared spectroscopy, respectively. Meanwhile, the energy level of the dyes, EHOMO and ELUMO was measured by cyclic voltammetry. The best energy level of curcumin dye was achieved at pH 3.5 where Ered = -0.37V, ELUMO = -4.28 eV, Eox = 1.15V, EHOMO = -5.83 eV, and Eband gap = 1.55 eV. Therefore, the purified curcumin dye added by benzoic acid was promising for sensitizing the dye-sensitized solar cells.

  12. Crystal field parameters and energy levels scheme of trivalent chromium doped BSO

    SciTech Connect

    Petkova, P.; Andreici, E.-L.; Avram, N. M.

    2014-11-24

    The aim of this paper is to give an analysis of crystal field parameters and energy levels schemes for the above doped material, in order to give a reliable explanation for experimental data. The crystal field parameters have been modeled in the frame of Exchange Charge Model (ECM) of the crystal field theory, taken into account the geometry of systems, with actually site symmetry of the impurity ions. The effect of the charges of the ligands and covalence bonding between chromium cation and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the crystal field parameters we simulated the scheme of energy levels of chromium ions by diagonalizing the matrix of the Hamiltonian of the doped crystal. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison with experiment shows that the results are quite satisfactory which justify the model and simulation scheme used for the title system.

  13. Energy transfer and energy level decay processes of Er3+ in water-free tellurite glass

    NASA Astrophysics Data System (ADS)

    Gomes, Laercio; Rhonehouse, Daniel; Nguyen, Dan T.; Zong, Jie; Chavez-Pirson, Arturo; Jackson, Stuart D.

    2015-12-01

    This report details the fundamental spectroscopic properties of a new class of water-free tellurite glasses studied for future applications in mid-infrared light generation. The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped Tellurium Zinc Lanthanum glass have been investigated using time-resolved fluorescence spectroscopy. The excited state dynamics was analyzed for Er2O3 concentrations between 0.5 mol% and 4 mol%. Selective laser excitation of the 4I11/2 energy level at 972 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that in a similar way to other Er3+-doped glasses, a strong energy-transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 μm transition. The 4I13/2 and 4I11/2 energy levels emitted luminescence with peaks located at 1532 nm and 2734 nm respectively with luminescence efficiencies of 100% and 8% for the higher (4 mol.%) concentration sample. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼57 kW cm-2 for a CW laser pump at 976 nm for [Er2O3] = 2 mol.%.

  14. Resonant nature of intrinsic defect energy levels in PbTe revealed by infrared photoreflectance spectroscopy

    SciTech Connect

    Zhang, Bingpo; Cai, Chunfeng; Jin, Shuqiang; Ye, Zhenyu; Wu, Huizhen; Qi, Zhen

    2014-07-14

    Step-scan Fourier-transform infrared photoreflectance and modulated photoluminescence spectroscopy were used to characterize the optical transitions of the epitaxial PbTe thin film grown by molecular beam epitaxy on BaF{sub 2} (111) substrate in the vicinity of energy gap of lead telluride at 77 K. It is found that the intrinsic defect energy levels in the electronic structure are of resonant nature. The Te-vacancy energy level is located above the conduction band minimum by 29.1 meV. Another defect (V{sub X}) energy level situated below valance band maximum by 18.1 meV is also revealed. Whether it is associated with the Pb vacancy is still not clear. It might also be related to the misfit dislocations stemming from the lattice mismatch between PbTe and BaF{sub 2} substrate. The experimental results support the theory prediction (N. J. Parada and G. W. Pratt, Jr., Phys. Rev. Lett. 22, 180 (1969), N. J. Parada, Phys. Rev. B 3, 2042 (1971)) and are consistent with the reported Hall experimental results (G. Bauer, H. Burkhard, H. Heinrich, and A. Lopez-Otero, J. Appl. Phys. 47, 1721 (1976)).

  15. Resonant nature of intrinsic defect energy levels in PbTe revealed by infrared photoreflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Bingpo; Cai, Chunfeng; Jin, Shuqiang; Ye, Zhenyu; Wu, Huizhen; Qi, Zhen

    2014-07-01

    Step-scan Fourier-transform infrared photoreflectance and modulated photoluminescence spectroscopy were used to characterize the optical transitions of the epitaxial PbTe thin film grown by molecular beam epitaxy on BaF2 (111) substrate in the vicinity of energy gap of lead telluride at 77 K. It is found that the intrinsic defect energy levels in the electronic structure are of resonant nature. The Te-vacancy energy level is located above the conduction band minimum by 29.1 meV. Another defect (VX) energy level situated below valance band maximum by 18.1 meV is also revealed. Whether it is associated with the Pb vacancy is still not clear. It might also be related to the misfit dislocations stemming from the lattice mismatch between PbTe and BaF2 substrate. The experimental results support the theory prediction (N. J. Parada and G. W. Pratt, Jr., Phys. Rev. Lett. 22, 180 (1969), N. J. Parada, Phys. Rev. B 3, 2042 (1971)) and are consistent with the reported Hall experimental results (G. Bauer, H. Burkhard, H. Heinrich, and A. Lopez-Otero, J. Appl. Phys. 47, 1721 (1976)).

  16. Quantum Mechanics on a Mobius Strip: Energy Levels, Symmetries, and Level Splitting in a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Li, Zehao; Ram-Mohan, Ramdas

    2012-02-01

    We investigate the energy levels of an electron on a M"obius strip. Schr"odinger's equation on this curved surface is shown to have terms that do not have invariance under parity transformation in parameter space for the strip. The double degeneracy of energy levels that exists for flat cylindrical rings is shown to be removed for the pairs of energies in the M"obius strip due to parity symmetry breaking. The orbital angular momentum is found to have approximately not only integer but also half-integer values of . The splitting of the energy levels in an external magnetic field is displayed. The effects of multiple twists are investigated to further clarify that the parity symmetry breaking is the effect of the curved geometry, while the appearance of half-integer angular momentum states is a topological effect. The implications for twisted rings composed of graphene will be discussed, and carrier transport through the M"obius strip will be considered. This work was supported by AFLR/DARPA under grant FA8650-10-1-7046.

  17. Level sequence and splitting identification of closely spaced energy levels by angle-resolved analysis of fluorescence light

    NASA Astrophysics Data System (ADS)

    Wu, Z. W.; Volotka, A. V.; Surzhykov, A.; Dong, C. Z.; Fritzsche, S.

    2016-06-01

    The angular distribution and linear polarization of the fluorescence light following the resonant photoexcitation is investigated within the framework of density matrix and second-order perturbation theory. Emphasis has been placed on "signatures" for determining the level sequence and splitting of intermediate (partially) overlapping resonances, if analyzed as a function of photon energy of incident light. Detailed computations within the multiconfiguration Dirac-Fock method have been performed, especially for the 1 s22 s22 p63 s ,Ji=1 /2 +γ1→(1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 →1 s22 s22 p63 s ,Jf=1 /2 +γ2 photoexcitation and subsequent fluorescence emission of atomic sodium. A remarkably strong dependence of the angular distribution and linear polarization of the γ2 fluorescence emission is found upon the level sequence and splitting of the intermediate (1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 overlapping resonances owing to their finite lifetime (linewidth). We therefore suggest that accurate measurements of the angular distribution and linear polarization might help identify the sequence and small splittings of closely spaced energy levels, even if they cannot be spectroscopically resolved.

  18. Self-energy-corrected electronic energy level alignment in molecular junctions and at interfaces with hybrid functionals

    NASA Astrophysics Data System (ADS)

    Kotiuga, Michele; Egger, David; Kronik, Leeor; Neaton, Jeffrey B.

    2015-03-01

    Accurate calculations of energy level alignment at complex interfaces are imperative for understanding a variety of transport and spectroscopy measurements, as well as for elucidating new interfacial electronic structure phenomena. However, standard approaches to such calculations, based on density functional theory (DFT), are well known to be deficient. In prior work on molecular junctions and physisorbed molecules on surfaces, an approximate GW approach, DFT+ Σ, has been successful in describing the conductance and level alignment of amine and pyridine terminated molecules on gold surfaces and in junctions. Here, via the use of hybrid functionals, we preform quantitative studies of the level alignment of thiol- and carbon-terminated phenyls on gold, where the formation of a strong chemical bond and presence of gateway states limit the validity of the DFT+ Σ approximation as currently formulated. We contrast these systems to prior work on weakly-coupled molecules, including bipyridine or phenyl-diamines. Additionally, we compute transmission functions using both DFT-PBE and DFT-HSE starting points and predict conductance and thermopower with these methods, comparing to experiments where possible. We acknowledge DOE, DOD, NERSC, ERC, ISF, and FWF.

  19. Calculation of energy levels, {ital E}1 transition amplitudes, and parity violation in francium

    SciTech Connect

    Dzuba, V.A.; Flambaum, V.V.; Sushkov, O.P.

    1995-05-01

    Many-body perturbation theory in the screened Coulomb interaction was used to calculate energy levels, {ital E}1 trransition amplitudes, and the parity-nonconserving (PNC) {ital E}1 amplitude of the 7{ital s}-8{ital s} transition in francium. The method takes into account the core-polarization effect, the second-order correlations, and the three dominating sequences of higher-order correlation diagrams: screening of the electron-electron interaction, particle-hole interaction, and the iterations of the self-energy operator. The result for the PNC amplitude for {sup 223}Fr is {ital E}1(7{ital s}-8{ital s})=(1.59{plus_minus}{similar_to}1%){times}10{sup {minus}10}{ital iea}{sub {ital B}}({minus}{ital Q}{sub {ital W}}/{ital N}), where {ital Q}{sub {ital W}} is the weak charge of the nucleus, {ital N}=136 is the number of neutrons, {ital e}={vert_bar}{ital e}{vert_bar} is the elementary charge, and {ital a}{sub {ital B}} is the Bohr radius. Our prediction for the position of the 8{ital s} energy level of Fr, which has not been measured yet, is 13 110 cm{sup {minus}1} below the limit of the continuous spectrum. The accuracy of the calculations was controlled by comparison with available experimental data and analogous calculations for cesium. It is estimated to be {similar_to}0.1% for the energy levels and {similar_to}1% for the transition amplitudes.

  20. Energy levels and radiative rates for transitions in Mg-like iron, cobalt and nickel

    SciTech Connect

    Aggarwal, K.M. . E-mail: k.aggarwal@qub.ac.uk; Tayal, Vikas; Gupta, G.P.; Keenan, F.P.

    2007-09-15

    Energy levels and radiative rates for electric dipole (E1) transitions among the lowest 141 levels of the (1s{sup 2}2s{sup 2}2p{sup 6}) 3l{sup 2}, 3l3l', and 3l4l configurations of Fe XV, Co XVI, and Ni XVII are calculated through the CIV3 code using extensive configuration-interaction (CI) wavefunctions. The important relativistic effects are included through the Breit-Pauli approximation. In order to keep the calculated energy splittings close to the experimental values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. The energy levels, including their orderings, are in excellent agreement with the available experimental results for all three ions. However, experimental energies are only available for a few levels. Since mixing among some levels is found to be very strong, it becomes difficult to identify these uniquely. Additionally, some discrepancies with other theoretical work (particularly for Ni XVII) are very large. Therefore, in order to confirm the level ordering as well as to assess the accuracy of energy levels and radiative rates, we have performed two other independent calculations using the GRASP and FAC codes. These codes are fully relativistic, but the CI in the calculations is limited to the basic (minimum) configurations only. This enables us to assess the importance of including elaborate CI for moderately charged ions. Additionally, we report results for electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions, and list lifetimes for all levels. Comparisons are made with other available experimental and theoretical results, and the accuracy of the present results is assessed.

  1. Potential energy surface and rovibrational energy levels of the H2-CS van der Waals complex.

    PubMed

    Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise; Marinakis, Sarantos

    2012-12-21

    Owing to its large dipole, astrophysicists use carbon monosulfide (CS) as a tracer of molecular gas in the interstellar medium, often in regions where H(2) is the most abundant collider. Predictions of the rovibrational energy levels of the weakly bound complex CS-H(2) (not yet observed) and also of rate coefficients for rotational transitions of CS in collision with H(2) should help to interpret the observed spectra. This paper deals with the first goal, i.e., the calculation of the rovibrational energy levels. A new four-dimensional intermolecular potential energy surface for the H(2)-CS complex is presented. Ab initio potential energy calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and midbond functions. The potential energy surface was obtained by an analytic fit of the ab initio data. The equilibrium structure of the H(2)-CS complex is found to be linear with the carbon pointing toward H(2) at the intermolecular separation of 8.6 a(o). The corresponding well depth is -173 cm(-1). The potential was used to calculate the rovibrational energy levels of the para-H(2)-CS and ortho-H(2)-CS complexes. The present work provides the first theoretical predictions of these levels. The calculated dissociation energies are found to be 35.9 cm(-1) and 49.9 cm(-1), respectively, for the para and ortho complexes. The second virial coefficient for the H(2)-CS pair has also been calculated for a large range of temperature. These results could be used to assign future experimental spectra and to check the accuracy of the potential energy surface.

  2. Experimental Energy Levels of HD18O and D_218O

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Naumenko, O. V.; Tashkun, S. A.; Liu, A.-W.; Hu, S.-M.

    2010-06-01

    Extended sets of experimental energy levels of HD18O and D_218O have been obtained as the result of the analysis of recent high-resolution spectra and previously reported data. Spectra of the enriched by deuterium and oxygen-18 water samples were recorded with a Bruker IFS 120HR spectrometer at room temperature in the 1000 - 9200 cm-1 range a,b for this purpose. The RITZ code h was used for analysis of the rotation-vibration transitions and the energy levels determination. New energy levels as well as comparison with previous experimental and theoretical studies will be presented. This work was supported by Grant nos. 06-03-39014 and 10-05-91176 of RFBR (Russia) and by Grant nos. 20903085 and 10574124 of NSFC (China). Work of SNM and SAT was also partly supported by CRDF (USA) Grant RUG1-2954-TO-09 and by RFBR. Grant 09-05-92508. A.-W. Liu et al., J. Mol. Spectrosc. 237, 149-162 (2006). H.-Y. Ni et al., Mol. Phys. 106, 1793-1801 (2008). J. Bellet et al., J. Mol. Spectrosc. 47, 388-402 (1973). J.W.C. Johns, J. Opt. Soc. Am. B2, 1340-1354 (1985). R.A. Toth, J. Mol. Spectrosc. 162, 41-54 (1993). W.F. Wang et al., J. Mol. Spectrosc. 176, 226-228 (1996). R.A. Toth, J. Mol. Structure, 742, 49-68 (2005). S.N. Mikhailenko et al., JQSRT, 110, 597-608 (2009). A. Liu et al., JQSRT, 110, 1781-1800 (2009). O.V. Naumenko et al., JQSRT, 111, 36-44 (2010).

  3. Corrections to the energy levels of a spin-zero particle bound in a strong field

    SciTech Connect

    Lee, R. N.; Milstein, A. I.; Karshenboim, S. G.

    2006-01-15

    Formulas for the corrections to the energy levels and wave functions of a spin-zero particle bound in a strong field are derived. The general case of the sum of a Lorentz-scalar potential and zero component of a Lorentz-vector potential is considered. The forms of the corrections differ essentially from those for spin-(1/2) particles. As an example of application of our results, we evaluated the electric polarizability of a ground state of a spin-zero particle bound in a strong Coulomb field.

  4. Additions to the spectrum and energy levels and critical compilation of doubly ionized boron, B III

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.; Ryabtsev, A. N.; Ekberg, J. O.; Kink, I.; Mannervik, S.; Martinson, I.

    2008-08-01

    We have undertaken the study of the Li-like spectrum of doubly ionized boron, B III. The spectroscopic data have been obtained with beam-foil spectroscopy and high-resolution spark spectroscopy. The experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. About 50 new transitions have been observed, and most of the previously known lines have been measured with improved accuracy. We have also critically evaluated all previous and recent data for this spectrum. Complete data on wavelengths and energy levels based on this analysis are tabulated.

  5. Diagrammatic treatment of coherent backscattering of intense light by cold atoms with degenerate energy levels

    NASA Astrophysics Data System (ADS)

    Shatokhin, V. N.; Blattmann, R.; Wellens, T.; Buchleitner, A.

    2014-08-01

    We present a generalization of the diagrammatic pump-probe approach to coherent backscattering (CBS) of intense laser light for atoms with degenerate energy levels. We employ this approach for a characterization of the double-scattering signal from optically pumped atoms with the transition Jg→Je=Jg+1 in the helicity-preserving polarization channel. We show that, in the saturation regime, the internal degeneracy becomes manifest for atoms with Jg≥1, leading to a faster decrease of the CBS enhancement factor with increasing saturation parameter than in the nondegenerate case.

  6. Energy levels and transition probabilities in doubly-ionized erbium (Er III).

    NASA Astrophysics Data System (ADS)

    Wyart, J.-F.; Blaise, J.; Bidelman, W. P.; Cowley, C. R.

    1997-11-01

    The spectrum of Er III reported by Becher (1966) was reanalysed with the support of new predictions of energies and transition probabilities. The number of energy levels was increased from 45 to 115, including two levels of 4f117s and the levels 3F3, 3F2 and 1G4 of the ground configuration 4f12. All 470 classified lines are reported with transition probabilities for most of them. Several of these lines had not yet been attributed to Er III in the spectrum of the star HR 465.

  7. Energy levels and lifetimes of Nd IV, Pm IV, Sm IV, and Eu IV

    SciTech Connect

    Dzuba, V. A.; Safronova, U. I.; Johnson, W. R.

    2003-09-01

    To address the shortage of experimental data for electron spectra of triply ionized rare-earth elements we have calculated energy levels and lifetimes of 4f{sup n+1} and 4f{sup n}5d configurations of Nd IV (n=2), Pm IV (n=3), Sm IV (n=4), and Eu IV (n=5) using Hartree-Fock and configuration-interaction methods. To control the accuracy of our calculations we also performed similar calculations for Pr III, Nd III, and Sm III, for which experimental data are available. The results are important, in particular, for physics of magnetic garnets.

  8. Effects of Dietary Energy Levels on the Physiological Parameters and Reproductive Performance of Gestating Gilts.

    PubMed

    Jin, S S; Jung, S W; Jang, J C; Chung, W L; Jeong, J H; Kim, Y Y

    2016-07-01

    This experiment was conducted to investigate the effects of dietary energy levels on the physiological parameters and reproductive performance of gestating first parity sows. A total of 52 F1 gilts (Yorkshire×Landrace) were allocated to 4 dietary treatments using a completely randomized design. Each treatment contained diets with 3,100, 3,200, 3,300, or 3,400 kcal of metabolizable energy (ME)/kg, and the daily energy intake of the gestating gilts in each treatment were 6,200, 6,400, 6,600, and 6,800 kcal of ME, respectively. During gestation, the body weight (p = 0.04) and weight gain (p = 0.01) of gilts linearly increased with increasing dietary energy levels. Backfat thickness was not affected at d110 of gestation by dietary treatments, but increased linearly (p = 0.05) from breeding to d 110 of gestation. There were no significant differences on the litter size or litter birth weight. During lactation, the voluntary feed intake of sows tended to decrease when the dietary energy levels increased (p = 0.08). No difference was observed in backfat thickness of the sows within treatments; increasing energy levels linearly decreased the body weight of sows (p<0.05) at d 21 of lactation and body weight gain during lactation (p<0.01). No significant differences were observed in the chemical compositions of colostrum and milk. Therefore, these results indicated that high-energy diets influenced the bodyweight and backfat thickness of sows during gestation and lactation. NRC (2012) suggested that the energy requirement of the gestation gilt should be between 6,678 and 7,932 kcal of ME/d. Similarly, our results suggested that 3,100 kcal of ME/kg is not enough to maintain the reproductive performance for gilts during gestation with 2 kg feed daily. Gilts in the treatment 3,400 kcal of ME/kg have a higher weaning number of piglets, but bodyweight and backfat loss were higher than other treatments during lactation. But bodyweight and backfat loss were higher than other

  9. Effects of Dietary Energy Levels on the Physiological Parameters and Reproductive Performance of Gestating Gilts

    PubMed Central

    Jin, S. S.; Jung, S. W.; Jang, J. C.; Chung, W. L.; Jeong, J. H.; Kim, Y. Y.

    2016-01-01

    This experiment was conducted to investigate the effects of dietary energy levels on the physiological parameters and reproductive performance of gestating first parity sows. A total of 52 F1 gilts (Yorkshire×Landrace) were allocated to 4 dietary treatments using a completely randomized design. Each treatment contained diets with 3,100, 3,200, 3,300, or 3,400 kcal of metabolizable energy (ME)/kg, and the daily energy intake of the gestating gilts in each treatment were 6,200, 6,400, 6,600, and 6,800 kcal of ME, respectively. During gestation, the body weight (p = 0.04) and weight gain (p = 0.01) of gilts linearly increased with increasing dietary energy levels. Backfat thickness was not affected at d110 of gestation by dietary treatments, but increased linearly (p = 0.05) from breeding to d 110 of gestation. There were no significant differences on the litter size or litter birth weight. During lactation, the voluntary feed intake of sows tended to decrease when the dietary energy levels increased (p = 0.08). No difference was observed in backfat thickness of the sows within treatments; increasing energy levels linearly decreased the body weight of sows (p<0.05) at d 21 of lactation and body weight gain during lactation (p<0.01). No significant differences were observed in the chemical compositions of colostrum and milk. Therefore, these results indicated that high-energy diets influenced the bodyweight and backfat thickness of sows during gestation and lactation. NRC (2012) suggested that the energy requirement of the gestation gilt should be between 6,678 and 7,932 kcal of ME/d. Similarly, our results suggested that 3,100 kcal of ME/kg is not enough to maintain the reproductive performance for gilts during gestation with 2 kg feed daily. Gilts in the treatment 3,400 kcal of ME/kg have a higher weaning number of piglets, but bodyweight and backfat loss were higher than other treatments during lactation. But bodyweight and backfat loss were higher than other

  10. COMPREHENSIVE OBSERVATIONS OF THE ULTRAVIOLET SPECTRUM AND IMPROVED ENERGY LEVELS FOR SINGLY IONIZED CHROMIUM (Cr II)

    SciTech Connect

    Sansonetti, Craig J.; Nave, Gillian; Reader, Joseph; Kerber, Florian

    2012-10-15

    We report new observations of the spectrum of singly ionized chromium (Cr II) in the region 1142-3954 A. The spectra were recorded with the National Institute of Standards and Technology 10.7 m normal-incidence vacuum spectrograph and FT700 vacuum ultraviolet Fourier transform spectrometer. More than 3600 lines are classified as transitions among 283 even and 368 odd levels. The new spectral data are used to re-optimize the energy levels, reducing their uncertainties by a typical factor of 20.

  11. A spectral-Lagrangian Boltzmann solver for a multi-energy level gas

    SciTech Connect

    Munafò, Alessandro; Haack, Jeffrey R.; Gamba, Irene M.; Magin, Thierry E.

    2014-05-01

    In this paper a spectral-Lagrangian method is proposed for the full, non-linear Boltzmann equation for a multi-energy level gas typical of a hypersonic re-entry flow. Internal energy levels are treated as separate species and inelastic collisions (leading to internal energy excitation and relaxation) are accounted for. The formulation developed can also be used for the case of a gas mixture made of monatomic gases without internal energy (where only elastic collisions occur). The advantage of the spectral-Lagrangian method lies in the generality of the algorithm in use for the evaluation of the elastic and inelastic collision operators, as well as the conservation of mass, momentum and energy during collisions. The latter is realized through the solution of constrained optimization problems. The computational procedure is based on the Fourier transform of the partial elastic and inelastic collision operators and exploits the fact that these can be written as weighted convolutions in Fourier space with no restriction on the cross-section model. The feasibility of the proposed approach is demonstrated through numerical examples for both space homogeneous and in-homogeneous problems. Computational results are compared with those obtained by means of the DSMC method in order to assess the accuracy of the proposed spectral-Lagrangian method.

  12. Seleno groups control the energy-level alignment between conjugated organic molecules and metals

    SciTech Connect

    Niederhausen, Jens; Heimel, Georg; Wilke, Andreas; Rabe, Jürgen P.; Duhm, Steffen; Bürker, Christoph; Schreiber, Frank; Xin, Qian; Vollmer, Antje; Kera, Satoshi; Ueno, Nobuo; Koch, Norbert

    2014-01-07

    The charge injection from metallic electrodes into hole transporting layers of organic devices often suffers from deviations from vacuum-level alignment at the interface. Even for weakly interacting cases, Pauli repulsion causes an interface dipole between the metal and conjugated organic molecules (COMs) (so called “push-back” or “cushion” effect), which leads notoriously to an increase of the hole injection barrier. On the other hand, for chalcogenol self assembled monolayers (SAMs) on metal surfaces, chemisorption via the formation of chalcogen-metal bonds is commonly observed. In these cases, the energy-level alignment is governed by chalcogen-derived interface states in the vicinity of the metal Fermi-level. In this work, we present X-ray and ultraviolet photoelectron spectroscopy data that demonstrate that the interfacial energy-level alignment mechanism found for chalcogenol SAMs also applies to seleno-functionalized COMs. This can be exploited to mitigate the push-back effect at metal contacts, notably also when COMs with low ionization energies are employed, permitting exceedingly low hole injection barriers, as shown here for the interfaces of tetraseleno-tetracene with Au(111), Ag(111), and Cu(111)

  13. Energy levels, radiative rates, and lifetimes for transitions in W LVIII

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Cl-like W LVIII. Configuration interaction (CI) has been included among 44 configurations (generating 4978 levels) over a wide energy range up to 363 Ryd, and the general-purpose relativistic atomic structure package (GRASP) adopted for the calculations. Since no other results of comparable complexity are available, calculations have also been performed with the flexible atomic code (FAC), which help in assessing the accuracy of our results. Energies are listed for the lowest 400 levels (with energies up to ∼98 Ryd), which mainly belong to the 3s{sup 2}3p{sup 5}, 3s3p{sup 6}, 3s{sup 2}3p{sup 4}3d, 3s{sup 2}3p{sup 3}3d{sup 2}, 3s3p{sup 4}3d{sup 2}, 3s{sup 2}3p{sup 2}3d{sup 3}, and 3p{sup 6}3d configurations, and radiative rates are provided for four types of transitions, i.e. E1, E2, M1, and M2. Our energy levels are assessed to be accurate to better than 0.5%, whereas radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  14. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives

    NASA Astrophysics Data System (ADS)

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L = cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF = N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.

  15. Spectrum and energy levels of five-times ionized zirconium (Zr VI)

    NASA Astrophysics Data System (ADS)

    Reader, Joseph; Lindsay, Mark D.

    2016-02-01

    We carried out a new analysis of the spectrum of five-times-ionized zirconium Zr VI. For this we used sliding-spark discharges together with normal- and grazing-incidence spectrographs to observe the spectrum from 160 to 2000 Å. These observations showed that the analysis of this spectrum by Khan et al (1985 Phys. Scr. 31 837) contained a significant number of incorrect energy levels. We have now classified ˜420 lines as transitions between 23 even-parity levels 73 odd-parity levels. The 4s24p5, 4s4p6, 4s24p44d, 5s, 5d, 6s configurations are now complete, although a few levels of 4s24p45d are tentative. We determined Ritz-type wavelengths for ˜135 lines from the optimized energy levels. The uncertainties range from 0.0003 to 0.0020 Å. Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels were used to interpret the observed configurations. Oscillator strengths for all classified lines were calculated with the fitted parameters. The results are compared with values for the level energies, percentage compositions, and transition probabilities from recent ab initio theoretical calculations. The ionization energy was revised to 777 380 ± 300 cm-1 (96.38 ± 0.04 eV).

  16. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    PubMed

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts.

  17. A new classification of the amino acid side chains based on doublet acceptor energy levels.

    PubMed Central

    Sneddon, S F; Morgan, R S; Brooks, C L

    1988-01-01

    We describe a new classification of the amino acid side chains based on the potential energy level at which each will accept an extra (doublet) electron. The doublet acceptor energy level, and the doublet acceptor orbital were calculated using semiempirical INDO/2-UHF molecular orbital theory. The results of these calculations show that the side chains fall into four groups. We have termed these groups repulsive, insulating, semiconducting, and attractive in accordance with where each lies on the relative energy scale. We use this classification to examine the role of residues between the donor and acceptor in modulating the rate and mechanism of electron transfer in proteins. With the calculated acceptor levels, we construct a potential barrier for those residues between the donor and acceptor. It is the area beneath this barrier that determines the decay of electronic coupling between donor and acceptor, and thus the transfer rate. We have used this schematic approach to characterize the four electron transfer pathways in myoglobin recently studied by Mayo et al. (Mayo, S.L., W.R. Ellis, R.J. Crutchley, and H.B. Gray. 1986. Science [Wash. DC]. 233:948-952). PMID:3342271

  18. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    PubMed

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts. PMID:26802538

  19. The molecular potential energy surface and vibrational energy levels of methyl fluoride. Part II.

    PubMed

    Manson, Steven A; Law, Mark M; Atkinson, Ian A; Thomson, Grant A

    2006-06-28

    New analytical bending and stretching, ground electronic state, potential energy surfaces for CH(3)F are reported. The surfaces are expressed in bond-length, bond-angle internal coordinates. The four-dimensional stretching surface is an accurate, least squares fit to over 2000 symmetrically unique ab initio points calculated at the CCSD(T) level. Similarly, the five-dimensional bending surface is a fit to over 1200 symmetrically unique ab initio points. This is an important first stage towards a full nine-dimensional potential energy surface for the prototype CH(3)F molecule. Using these surfaces, highly excited stretching and (separately) bending vibrational energy levels of CH(3)F are calculated variationally using a finite basis representation method. The method uses the exact vibrational kinetic energy operator derived for XY(3)Z systems by Manson and Law (preceding paper, Part I, Phys. Chem. Chem. Phys., 2006, 8, DOI: 10.1039/b603106d). We use the full C(3v) symmetry and the computer codes are designed to use an arbitrary potential energy function. Ultimately, these results will be used to design a compact basis for fully coupled stretch-bend calculations of the vibrational energy levels of the CH(3)F system.

  20. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  1. Energy level decay and excited state absorption processes in erbium-doped tellurite glass

    NASA Astrophysics Data System (ADS)

    Gomes, Laércio; Oermann, Michael; Ebendorff-Heidepriem, Heike; Ottaway, David; Monro, Tanya; Felipe Henriques Librantz, André; Jackson, Stuart D.

    2011-10-01

    The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped tellurite (TZNL) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the 4I11/2 energy level at 970 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that energy transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 μm transition. This upconversion has been analyzed for Er2O3 concentrations between 0.5 mol. % and 2.2 mol. %. The 4I13/2 and 4I11/2 energy levels emit luminescence with peaks located at 1532 nm and 2734 nm, respectively, with radiative decay efficiencies of 65% and 6.8% for the higher (2.2 mol. %) concentration sample. The low 2.7 μm emission efficiency is due to the non-radiative decay bridging the 4I11/2 → 4I13/2 transition and energy transfer to the OH- groups in the glass. Excited state absorption was observed to occur from the 4I13/2 and 4I11/2 levels with peak absorptions occurring at 1550 nm and 971 nm, respectively. The decay time of the 4I11/2 excited state decreased with an increase in the Er3+ concentration, which related to energy transfer to OH- ions that had a measured concentration of 6.6 × 1018 cm-3. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ˜80 kW cm-2 for a cw laser pump at 976 nm if [Er3+] ≥ 1.2 × 1021 cm-3 (or [Er2O3] ≥ 2.65 mol. %) without OH- impurities being present.

  2. Myocardial signal density levels and beam-hardening artifact attenuation using dual-energy computed tomography.

    PubMed

    Rodriguez-Granillo, Gaston A; Carrascosa, Patricia; Cipriano, Silvina; de Zan, Macarena; Deviggiano, Alejandro; Capunay, Carlos; Cury, Ricardo C

    2015-01-01

    The assessment of myocardial perfusion using single-energy (SE) imaging is influenced by beam-hardening artifacts (BHA). We sought to explore the ability of dual-energy (DE) imaging to attenuate the presence of BHA. Myocardial signal density (SD) was evaluated in 2240 myocardial segments (112 for each energy level) and in 320 American Heart Association segments among the SE group. Compared to DE reconstructions at the best energy level, SE acquisitions showed no significant differences overall regarding myocardial SD or signal-to-noise ratio. The segments most commonly affected by BHA showed significantly lower myocardial SD at the lowest energy levels, progressively normalizing at higher energy levels.

  3. Enzymatic versus inorganic oxygen reduction catalysts: comparison of the energy levels in a free-energy scheme.

    PubMed

    Kjaergaard, Christian H; Rossmeisl, Jan; Nørskov, Jens K

    2010-04-19

    In this paper, we present a method to directly compare the energy levels of intermediates in enzymatic and inorganic oxygen reduction catalysts. We initially describe how the energy levels of a Pt(111) catalyst, operating at pH = 0, are obtained. By a simple procedure, we then convert the energy levels of cytochrome c oxidase (CcO) models obtained at physiological pH = 7 to the energy levels at pH = 0, which allows for comparison. Furthermore, we illustrate how different bias voltages will affect the free-energy landscapes of the catalysts. This allows us to determine the so-called theoretical overpotential of each system, which is shown to be significantly lower for the enzymatic catalysts compared to the inorganic Pt(111) catalyst. Finally, we construct theoretical polarization curves for the CcO models, in order to illustrate the effect of the low overpotentials on turnover rates per site. PMID:20380458

  4. Charge separation at nanoscale interfaces: Energy-level alignment including two-quasiparticle interactions

    SciTech Connect

    Li, Huashan; Lin, Zhibin; Lusk, Mark T. Wu, Zhigang

    2014-10-21

    The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

  5. Accuracy of analytic energy level formulas applied to hadronic spectroscopy of heavy mesons

    NASA Technical Reports Server (NTRS)

    Badavi, Forooz F.; Norbury, John W.; Wilson, John W.; Townsend, Lawrence W.

    1988-01-01

    Linear and harmonic potential models are used in the nonrelativistic Schroedinger equation to obtain article mass spectra for mesons as bound states of quarks. The main emphasis is on the linear potential where exact solutions of the S-state eigenvalues and eigenfunctions and the asymptotic solution for the higher order partial wave are obtained. A study of the accuracy of two analytical energy level formulas as applied to heavy mesons is also included. Cornwall's formula is found to be particularly accurate and useful as a predictor of heavy quarkonium states. Exact solution for all partial waves of eigenvalues and eigenfunctions for a harmonic potential is also obtained and compared with the calculated discrete spectra of the linear potential. Detailed derivations of the eigenvalues and eigenfunctions of the linear and harmonic potentials are presented in appendixes.

  6. Wave energy level and geographic setting correlate with Florida beach water quality.

    PubMed

    Feng, Zhixuan; Reniers, Ad; Haus, Brian K; Solo-Gabriele, Helena M; Kelly, Elizabeth A

    2016-03-15

    Many recreational beaches suffer from elevated levels of microorganisms, resulting in beach advisories and closures due to lack of compliance with Environmental Protection Agency guidelines. We conducted the first statewide beach water quality assessment by analyzing decadal records of fecal indicator bacteria (enterococci and fecal coliform) levels at 262 Florida beaches. The objectives were to depict synoptic patterns of beach water quality exceedance along the entire Florida shoreline and to evaluate their relationships with wave condition and geographic location. Percent exceedances based on enterococci and fecal coliform were negatively correlated with both long-term mean wave energy and beach slope. Also, Gulf of Mexico beaches exceeded the thresholds significantly more than Atlantic Ocean ones, perhaps partially due to the lower wave energy. A possible linkage between wave energy level and water quality is beach sand, a pervasive nonpoint source that tends to harbor more bacteria in the low-wave-energy environment.

  7. Calculation of energy levels and transition amplitudes for barium and radium.

    SciTech Connect

    Dzuba, V. A.; Flambaum, V. V.; Physics; Univ. of New South Wales

    2007-01-01

    The radium atom is a promising system for studying parity and time invariance violating weak interactions. However, available experimental spectroscopic data for radium are insufficient for designing an optimal experimental setup. We calculate the energy levels and transition amplitudes for radium states of significant interest. Forty states corresponding to all possible configurations consisting of the 7s, 7p and 6d single-electron states as well as the states of the 7s8s, 7s8p and 7s7d configurations have been calculated. The energies of ten of these states corresponding to the 6d{sup 2}, 7s8s, 7p{sup 2} and 6d7p configurations are not known from experiment. Calculations for barium are used to control the accuracy.

  8. Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy.

    PubMed

    Gobbi, M; Pietrobon, L; Atxabal, A; Bedoya-Pinto, A; Sun, X; Golmar, F; Llopis, R; Casanova, F; Hueso, L E

    2014-01-01

    The energetics of metal/molecular semiconductor interfaces plays a fundamental role in organic electronics, determining the performance of very diverse devices. So far, information about the energy level alignment has been most commonly gained by spectroscopy techniques that typically require experimental conditions far from the real device operation. Here we demonstrate that a simple three-terminal device allows the acquisition of spectroscopic information about the metal/molecule energy alignment in real operative condition. As a proof of principle, we employ the proposed device to measure the energy barrier height between different clean metals and C60 molecules and we recover typical results from photoemission spectroscopy. The device is designed to inject a hot electron current directly into the molecular level devoted to charge transport, disentangling the contributions of both the interface and the bulk to the device total resistance, with important implications for spintronics and low-temperature physics.

  9. Energy levels and radiative rates for Cr-like Cu VI and Zn VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2016-09-01

    Energy levels and radiative rates (A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

  10. Energy levels, lifetimes, and transition probabilities for Mn XII and Ge XIX

    SciTech Connect

    El-Sayed, Fatma

    2014-09-15

    Energy levels, transition probabilities, oscillator strengths, line strengths, and lifetimes have been calculated for silicon-like manganese and germanium, Mn XII and Ge XIX. The configurations 3s{sup 2}3p{sup 2}, 3s3p{sup 3}, 3s{sup 2}3p3d, 3s3p{sup 2}3d, and 3p{sup 4} were used in the calculations and 88 fine-structure levels were obtained. The fully relativistic GRASP code has been adopted, and results are reported for all electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole transitions among levels of Mn XII and Ge XIX. Comparisons have been made with available theoretical and experimental results.

  11. Interacting Electrons in Parabolic Quantum Dots:. Energy Levels, Addition Energies, and Charge Distributions

    NASA Astrophysics Data System (ADS)

    Schreiber, Michael; Siewert, Jens; Vojta, Thomas

    We investigate the properties of interacting electrons in a parabolic confinement. To this end we numerically diagonalize the Hamiltonian using the Hartree-Fock based diagonalization method which is related to the configuration interaction approach. We study different types of interactions, Coulomb as well as short range. In addition to the ground state energy we calculate the spatial charge distribution and compare the results to those of the classical calculation. We find that a sufficiently strong screened Coulomb interaction produces energy level bunching for classical as well as for quantum-mechanical dots. Bunching in the quantum-mechanical system occurs due to an interplay of kinetic and interaction energy, moreover, it is observed well before reaching the limit of a Wigner crystal. It also turns out that the shell structure of classical and quantum mechanical spatial charge distributions is quite similar.

  12. Interacting Electrons in Parabolic Quantum Dots:. Energy Levels, Addition Energies, and Charge Distributions

    NASA Astrophysics Data System (ADS)

    Schreiber, Michael; Siewert, Jens; Vojta, Thomas

    2001-08-01

    We investigate the properties of interacting electrons in a parabolic confinement. To this end we numerically diagonalize the Hamiltonian using the Hartree-Fock based diagonalization method which is related to the configuration interaction approach. We study different types of interactions, Coulomb as well as short range. In addition to the ground state energy we calculate the spatial charge distribution and compare the results to those of the classical calculation. We find that a sufficiently strong screened Coulomb interaction produces energy level bunching for classical as well as for quantum-mechanical dots. Bunching in the quantum-mechanical system occurs due to an interplay of kinetic and interaction energy, moreover, it is observed well before reaching the limit of a Wigner crystal. It also turns out that the shell structure of classical and quantum mechanical spatial charge distributions is quite similar.

  13. Energy levels and spectral lines in the X-ray spectra of highly charged W XLIV

    NASA Astrophysics Data System (ADS)

    Hao, Liang-Huan; Kang, Xiao-Ping

    2014-07-01

    The multi-configuration Dirac-Hartree-Fock method is employed to calculate the fine-structure energy levels, wavelengths, transition probabilities, and oscillator strengths for electric dipole allowed (E1) and forbidden (M1, E2, M2) lines for the 4 s 24 p and 4 s4 p 2 configurations of W XLIV. The valence-valence and core-valence correlation effects are accounted for in a systematic way. Breit interactions and quantum electrodynamics (QED) effects are estimated in subsequent relativistic configuration interaction (CI) calculations. The present results are in good agreement with other available theoretical and experimental values, and we predict new data for several levels where no other theoretical and/or experimental results are available, precise measurements are clearly needed here.

  14. Controlling energy level offsets in organic/organic heterostructures using intramolecular polar bonds

    NASA Astrophysics Data System (ADS)

    Duhm, Steffen; Salzmann, Ingo; Heimel, Georg; Oehzelt, Martin; Haase, Anja; Johnson, Robert L.; Rabe, Jürgen P.; Koch, Norbert

    2009-01-01

    The impact of intramolecular polar bonds (IPBs) on the energy level alignment in layered systems of rodlike conjugated molecules standing on the substrate was investigated for pentacene (PEN) and perfluoropentacene (PFP) on SiO2 using ultraviolet photoelectron spectroscopy. A remarkably large energy offset of 1.75 eV was found between the highest occupied molecular orbital (HOMO) levels of PEN and PFP caused by IPBs at the surface of standing PFP layers. This large HOMO-level offset results in a narrow intermolecular energy gap of approximately 0.4 eV at the interface between PEN and PFP layers. However, the absence of significant spatial overlap of PEN and PFP electron wave functions across the layers suppresses interlayer optical transitions.

  15. Energy level alignment at the methylammonium lead iodide/copper phthalocyanine interface

    SciTech Connect

    Chen, Shi; Goh, Teck Wee; Sum, Tze Chien E-mail: Tzechien@ntu.edu.sg; Sabba, Dharani; Chua, Julianto; Mathews, Nripan; Huan, Cheng Hon Alfred E-mail: Tzechien@ntu.edu.sg

    2014-08-01

    The energy level alignment at the CH{sub 3}NH{sub 3}PbI{sub 3}/copper phthalocyanine (CuPc) interface is investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). XPS reveal a 0.3 eV downward band bending in the CuPc film. UPS validate this finding and further reveal negligible interfacial dipole formation – verifying the viability of vacuum level alignment. The highest occupied molecular orbital of CuPc is found to be closer to the Fermi level than the valance band maximum of CH{sub 3}NH{sub 3}PbI{sub 3}, facilitating hole transfer from CH{sub 3}NH{sub 3}PbI{sub 3} to CuPc. However, subsequent hole extraction from CuPc may be impeded by the downward band bending in the CuPc layer.

  16. Energy level broadening of defects causing nonideality in nearly ideal Si Schottky barriers

    NASA Astrophysics Data System (ADS)

    Maeda, Keiji

    2004-10-01

    We have proposed a mechanism of the local Schottky barrier height (SBH) lowering to explain the nonideal characteristics in Si SBs. Positively charged defects close to the M/S interface induce image charge in the metal-induced gap states (MIGS) and lower the SBH. Based on this mechanism, the inhomogeneous potential distributions in the proximity of the MIGS are calculated in agreement with the I- V characteristics. The energy level of the defect, identified with Si self-interstitial, is in agreement with the theoretical value. The energy width of the defect is nearly equal to the standard deviation in the Gaussian distribution describing the SBH inhomogeneity. Thus, the propriety of the model is confirmed.

  17. Isomeric and ground state energy level measurements of natural tellurium isotopes via (γ,n) reaction

    NASA Astrophysics Data System (ADS)

    Tamkas, M.; Akcali, O.; Durusoy, A.

    2015-04-01

    We have planned to measure isomeric and ground state energy levels in 120Te(γ,n)119m,gTe, 122Te(γ,n)121m,gTe, 128Te(γ,n)127m,gTe, 130Te(γ,n)129m,gTe photonuclear reactions of natural tellurium induced by bremsstrahlung photons with end-point energy at 18 MeV. The sample was irradiated in the clinical linear electron accelerator (Philips SLi-25) at Akdeniz University Hospital. The gamma spectrum of the tellurium sample was measured using HP(Ge) semiconductor detector (ORTEC) and multi channel analyzer. We used both MAESTRO (ORTEC) and home made root based gui program (Theia) for data analyzing. The obtained experimental data values are compared with NUDAT energy values.

  18. Energy levels and radiative rates for Cr-like Cu VI and Zn VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2016-09-01

    Energy levels and radiative rates (A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

  19. Time resolved fluorescence from parity mixed rotational energy levels - Collisions vs electric field effects

    NASA Astrophysics Data System (ADS)

    Mandich, M. L.; Gaebe, C. E.; Gottscho, R. A.

    1985-10-01

    Moore et al. (1984) have described a method for the in situ and nonintrusive measurement of plasma electric fields by a method involving the excitation of a parity or Lambda doublet of the polar diatomic molecule BCl. Three approximations are made in deriving a theoretical relationship between field strength and the forbidden to allowed line intensity ratio. One approximation is related to the neglect of collisional transfer, while another is based on the neglect of coherent phenomena, such as quantum beats between the mixed parity levels. New experimental evidence is provided, and it is shown that the latter approximation is not always justified. The last assumption is the neglect of hyperfine structure effects on field-dependent line intensities and polarizations. Hyperfine effects are accounted for in a phenomenological fashion which is justified empirically. Attention is given to both time-resolved and time-integrated fluorescence measurements from parity-mixed energy levels in the polar diatomic molecule BCl.

  20. Wave energy level and geographic setting correlate with Florida beach water quality.

    PubMed

    Feng, Zhixuan; Reniers, Ad; Haus, Brian K; Solo-Gabriele, Helena M; Kelly, Elizabeth A

    2016-03-15

    Many recreational beaches suffer from elevated levels of microorganisms, resulting in beach advisories and closures due to lack of compliance with Environmental Protection Agency guidelines. We conducted the first statewide beach water quality assessment by analyzing decadal records of fecal indicator bacteria (enterococci and fecal coliform) levels at 262 Florida beaches. The objectives were to depict synoptic patterns of beach water quality exceedance along the entire Florida shoreline and to evaluate their relationships with wave condition and geographic location. Percent exceedances based on enterococci and fecal coliform were negatively correlated with both long-term mean wave energy and beach slope. Also, Gulf of Mexico beaches exceeded the thresholds significantly more than Atlantic Ocean ones, perhaps partially due to the lower wave energy. A possible linkage between wave energy level and water quality is beach sand, a pervasive nonpoint source that tends to harbor more bacteria in the low-wave-energy environment. PMID:26892203

  1. S-matrix Calculations of Energy Levels of the Lithium Isoelectronic Sequence

    SciTech Connect

    sapirstein, J; Cheng, K T

    2010-11-02

    A QED approach to the calculation of the spectra of the lithium isoelectronic sequence is implemented. A modified Furry representation based on the Kohn-Sham potential is used to evaluate all one- and two-photon diagrams with the exception of the two-loop Lamb shift. Three-photon diagrams are estimated with Hamiltonian methods. After incorporating recent calculations of the two-loop Lamb shift and recoil corrections a comprehensive tabulation of the 2s, 2p{sub 1/2} and 2p{sub 3/2} energy levels as well as the 2s - 2p{sub 1/2} and 2s - 2p{sub 3/2} transition energies for Z = 10 - 100 is presented.

  2. Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy.

    PubMed

    Gobbi, M; Pietrobon, L; Atxabal, A; Bedoya-Pinto, A; Sun, X; Golmar, F; Llopis, R; Casanova, F; Hueso, L E

    2014-01-01

    The energetics of metal/molecular semiconductor interfaces plays a fundamental role in organic electronics, determining the performance of very diverse devices. So far, information about the energy level alignment has been most commonly gained by spectroscopy techniques that typically require experimental conditions far from the real device operation. Here we demonstrate that a simple three-terminal device allows the acquisition of spectroscopic information about the metal/molecule energy alignment in real operative condition. As a proof of principle, we employ the proposed device to measure the energy barrier height between different clean metals and C60 molecules and we recover typical results from photoemission spectroscopy. The device is designed to inject a hot electron current directly into the molecular level devoted to charge transport, disentangling the contributions of both the interface and the bulk to the device total resistance, with important implications for spintronics and low-temperature physics. PMID:24946715

  3. S-matrix calculations of energy levels of the lithium isoelectronic sequence

    NASA Astrophysics Data System (ADS)

    Sapirstein, J.; Cheng, K. T.

    2012-06-01

    A QED approach to the calculation of the spectra of the lithium isoelectronic sequence is implemented. A modified Furry representation based on the Kohn-Sham potential is used to evaluate all one- and two-photon diagrams with the exception of the two-loop Lamb shift. Three-photon diagrams are estimated with Hamiltonian methods. After incorporating recent calculations of the two-loop Lamb shift and recoil corrections a comprehensive tabulation of the 2s, 2p1/2 and 2p3/2 energy levels as well as the 2s-2p1/2 and 2s-2p3/2 transition energies for Z=10-100 is presented.

  4. S-matrix calculations of energy levels of the lithium isoelectronic sequence

    NASA Astrophysics Data System (ADS)

    Sapirstein, J.; Cheng, K. T.

    2011-01-01

    A QED approach to the calculation of the spectra of the lithium isoelectronic sequence is implemented. A modified Furry representation based on the Kohn-Sham potential is used to evaluate all one- and two-photon diagrams with the exception of the two-loop Lamb shift. Three-photon diagrams are estimated with Hamiltonian methods. After incorporating recent calculations of the two-loop Lamb shift and recoil corrections, a comprehensive tabulation of the 2s, 2p1/2, and 2p3/2 energy levels as well as the 2s-2p1/2 and 2s-2p3/2 transition energies for Z=10-100 is presented.

  5. Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Karpuškienė, R.; Keenan, F. P.; Kisielius, R.; Stancalie, V.

    2016-01-01

    We report calculations of energy levels and radiative rates (A-values) for transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock (QRHF) code is adopted for calculating the data although GRASP (general-purpose relativistic atomic structure package) and flexible atomic code (FAC) have also been employed for comparison purposes. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST for a majority of the levels. However, there are discrepancies for a few levels of up to 3%. The A-values are listed for all significantly contributing E1, E2 and M1 transitions, and the corresponding lifetimes reported, although unfortunately no previous theoretical or experimental results exist to compare with our data.

  6. Spectrum and energy levels of quadruply-ionized molybdenum (Mo V)

    NASA Astrophysics Data System (ADS)

    Reader, Joseph; Tauheed, Ahmad

    2015-07-01

    The spectrum of quadruply-ionized molybdenum Mo V was observed from 200 to 4700 Å with sliding spark discharges on 10.7 m normal- and grazing-incidence spectrographs. The existing analyses of this spectrum (Tauheed et al 1985 Phys. Scr. 31 369; Cabeza et al 1986 Phys. Scr. 34 223) were extended to include the 5s2, 5p2, 5s5d, 5s6s, 4d5f, and 4d5g configurations as well as the missing 3H6 level of 4d4f and about 75 levels of the core-excited configuration 4p54d3. The values of the 4d5d 1S0, 5s5p 1P1, and 4d6p 3P0 levels were revised. There are now about 900 lines classified as transitions between 66 even parity and 191 odd parity energy levels. Of these, about 600 lines and 130 levels are new. From the optimized energy level values, Ritz-type wavelengths were determined for about 380 lines, with uncertainties varying from 0.0003 to 0.002 Å. The observed configurations were theoretically interpreted by means of Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels. The fitted parameters were used to calculate oscillator strengths for all classified lines. A few unclassified lines and undesignated levels are also given. An improved value for the ionization energy was obtained by combining the observed energy of the 4d5g configuration with an ab initio calculation of its term value. The adopted value is 438 900 ± 150 cm-1 (54.417 ± 0.019 eV).

  7. Energy levels, radiative rates, and lifetimes for transitions in W XL

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Br-like tungsten, W XL, calculated with the general-purpose relativistic atomic structure package (GRASP). Configuration interaction (CI) has been included among 46 configurations (generating 4215 levels) over a wide energy range up to 213 Ryd. However, for conciseness results are only listed for the lowest 360 levels (with energies up to ∼43 Ryd), which mainly belong to the 4s{sup 2}4p{sup 5},4s{sup 2}4p{sup 4}4d,4s{sup 2}4p{sup 4}4f,4s4p{sup 6},4p{sup 6}4d,4s4p{sup 5}4d,4s{sup 2}4p{sup 3}4d{sup 2}, and 4s{sup 2}4p{sup 3}4d4f configurations, and provided for four types of transitions, E1, E2, M1, and M2. Comparisons are made with existing (but limited) results. However, to fully assess the accuracy of our data, analogous calculations have been performed with the flexible atomic code, including an even larger CI than in GRASP. Our energy levels are estimated to be accurate to better than 0.02 Ryd, whereas results for radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  8. A few remarks on the simulation and use of crystal field energy level schemes of the rare earth ions

    NASA Astrophysics Data System (ADS)

    Hölsä, Jorma; Lastusaari, Mika; Maryško, Miroslav; Tukia, Mika

    2005-02-01

    The usefulness of the simulation of the energy level schemes of the trivalent rare earth ( R3+) ions in the prediction of the properties of the rare earth compounds is demonstrated for a few selected cases emphasizing the connection between different spectroscopic and magnetic properties of the R 3+ ions. The importance of the calculated energy level schemes in the UV-VUV range in interpreting complicated spectra and designing new phosphors by energy transfer and quantum cutting is described. In the absence of direct measurements, the calculated energy level values can be very useful. The possibilities to interpret the magnetic properties of the R3+ (and R2+) ions are described by using the wave functions of the energy levels obtained from the energy level simulations. As a fine example, it is shown how the amount of an Eu 2+ impurity can be obtained from the calculation of the paramagnetic susceptibility as a function of temperature. The problems involved in the simulation of the 7FJ crystal field energy level scheme of the Eu 3+ ion are highlighted by using a comparison between the extensive literature data and calculated level schemes.

  9. Density Visualization

    ERIC Educational Resources Information Center

    Keiter, Richard L.; Puzey, Whitney L.; Blitz, Erin A.

    2006-01-01

    Metal rods of high purity for many elements are now commercially available and may be used to construct a display of relative densities. We have constructed a display with nine metal rods (Mg, Al, Ti, V, Fe, Cu, Ag, Pb, and W) of equal mass whose densities vary from 1.74 to 19.3 g cm[superscript -3]. The relative densities of the metals may be…

  10. The performance of brown egg-type layers fed different protein and energy levels in the tropics.

    PubMed

    Olomu, J M; Offiong, S A

    1983-02-01

    The effects of feeding three protein levels (16, 18, and 20%), each at three metabolizable energy levels (2400, 2600, and 2800 kcal/kg diet), were studied with 990 caged Warren Studler Sex-Sal Link pullets over a 336-day laying period. Dietary protein had no significant effects on hen-day egg production, egg weight, Haugh units, feed intake, feed conversion, feed cost per dozen eggs, caloric intake, egg weights, and final body weight. Protein consumption on all levels of dietary protein was over 20 g per bird per day and increased significantly with increases in dietary protein. Mortality was lowest on the highest protein level. The highest energy level (2800 kcal/kg diet) significantly depressed egg production and feed and protein intake. The feed costs per dozen eggs increased significantly with increases in dietary energy level. Caloric intake and final body weights were similar for the medium (2600 kcal/kg diet) and highest energy levels (2800 kcal/kg diet) but significantly higher than that obtained on the lowest energy level (2400 kcal/kg diet). Egg weights, Haugh units, feed per dozen eggs, and mortality were not significantly affected by energy levels. In spite of the average maximum monthly temperatures, ranging from 26.8 to 35.2 C, annual egg production was about 71 to 73% for the best groups, figures comparable with those obtainable in temperate climates. Egg weight and Haugh units were similar to reported temperate zone values. This experiment supports the use of 16% protein and a metabolizable energy level of 2400 kcal/kg diet for brown egg-type layers.

  11. Wavelengths, energy levels and hyperfine structure of Mn II and Sc II.

    NASA Astrophysics Data System (ADS)

    Nave, Gillian; Pickering, Juliet C.; Townley-Smith, Keeley I. M.; Hala, .

    2015-08-01

    For many decades, the Atomic Spectroscopy Groups at the National Institute of Standards and Technology (NIST) and Imperial College London (ICL) have measured atomic data of astronomical interest. Our spectrometers include Fourier transform (FT) spectrometers at NIST and ICL covering the region 1350 Å to 5.5 μm and a 10.7-m grating spectrometer at NIST covering wavelengths from 300 - 5000 Å. Sources for these spectra include high-current continuous and pulsed hollow cathode (HCL) lamps, Penning discharges, and sliding spark discharges. Recent work has focused on the measurement and analysis of wavelengths, energy levels, and hyperfine structure (HFS) constants for iron-group elements. The analysis of FT spectra of Cr I, Mn I, and Mn II is being led by ICL and is described in a companion poster [1]. Current work being led by NIST includes the analysis of HFS in Mn II, analysis of Mn II in the vacuum ultraviolet, and a comprehensive analysis of Sc II.Comprehensive HFS constants for Mn II are needed for the interpretation of stellar spectra and incorrect abundances may be obtained when HFS is omitted. Holt et al. [2] have measured HFS constants for 59 levels of Mn II using laser spectroscopy. We used FT spectra of Mn/Ni and Mn/Cu HCLs covering wavelength ranges from 1350 Å to 5.4 μm to confirm 26 of the A constants of Holt et al. and obtain values for roughly 40 additional levels. We aim to obtain HFS constants for the majority of lines showing significant HFS that are observed in chemically-peculiar stars.Spectra of Sc HCLs have been recorded from 1800 - 6700 Å using a vacuum ultraviolet FT spectrometer at NIST. Additional measurements to cover wavelengths above 6700 Å and below 1800 Å are in progress. The spectra are being analyzed by NIST and Alighar Muslim University, India in order to derive improved wavelengths, energy levels, and hyperfine structure parameters.This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK

  12. Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications

    SciTech Connect

    Pérez, E. Castán, H.; García, H.; Dueñas, S.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G.; Olea, J.

    2015-01-12

    In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon.

  13. Spectrum and energy levels of the Yb4+ free ion (Yb V)

    NASA Astrophysics Data System (ADS)

    Meftah, Ali; Wyart, Jean-François; Tchang-Brillet, Wan-Ü. Lydia; Blaess, Christophe; Champion, Norbert

    2013-10-01

    The spectrum of ionized ytterbium produced by a sliding spark source was recorded on the 10 m high resolution vacuum ultraviolet normal-incidence spectrograph of the Meudon Observatory. About 1080 lines attributed to Yb V, hitherto unknown, have been identified. The analysis of this spectrum established all the energy levels of the ground configuration 4f12 and, respectively 174, 12 and 43 levels of the excited configurations 4f115d,4f116s and 4f116p. The theoretical calculations by means of the Cowan codes included a least-squares optimization of the relevant radial parameters by minimizing the differences between calculated and experimental level energies, which led to mean errors of 55 cm-1 for the 56 even parity levels and 51 cm-1 for the 186 odd parity ones. Interactions with the unknown core-excited configurations 5p54f13, 5p54f126p, 5p54f125d and 5p54f126s were taken into account.

  14. Fine-structure energy levels and autoionizing width calculations of magnesium-like Ni XVII

    NASA Astrophysics Data System (ADS)

    Liang, Liang; Gao, Wenjing; Zhou, Chao; Zhang, Ling

    2013-05-01

    We have calculated highly excited fine-structure energy levels and their autoionizing width of 3 pns 3 P 1 ( n = 11-26), 3 pns 1 P 1 ( n = 10-22), 3 pnd 3 D 1 ( n = 11-26), 3 pnd 3 P 1 ( n = 10-21), 3 pnd 1 P 1( n = 10-21), 3 dnp 3 D 1 ( n = 7-30), 3 dnp 3 P 1 ( n = 7-28), 3 dnp 1 P 1 ( n = 7-28), 3 dnf 3 D 1 ( n = 7, 9-27), 3 dnf 3 P 1 ( n = 7, 9-27), and 3 dnf 1 P 1 ( n = 7, 9-27) for magnesium-like Ni XVII. The calculations are based upon the relativistic Breit-Pauli R-matrix approximation combining with the QB method of Quigley-Berrington (L. Quigley, K. A. Berrington, Pelan J. Comput. Phys. Commun. 114, 225 (1998)). We have reported the many unpublished energy values and autoionizing width of the J = 1 odd states of magnesium-like Ni XVII.

  15. Conjugated polymer energy level shifts in lithium-ion battery electrolytes.

    PubMed

    Song, Charles Kiseok; Eckstein, Brian J; Tam, Teck Lip Dexter; Trahey, Lynn; Marks, Tobin J

    2014-11-12

    The ionization potentials (IPs) and electron affinities (EAs) of widely used conjugated polymers are evaluated by cyclic voltammetry (CV) in conventional electrochemical and lithium-ion battery media, and also by ultraviolet photoelectron spectroscopy (UPS) in vacuo. By comparing the data obtained in the different systems, it is found that the IPs of the conjugated polymer films determined by conventional CV (IPC) can be correlated with UPS-measured HOMO energy levels (EH,UPS) by the relationship EH,UPS = (1.14 ± 0.23) × qIPC + (4.62 ± 0.10) eV, where q is the electron charge. It is also found that the EAs of the conjugated polymer films measured via CV in conventional (EAC) and Li(+) battery (EAB) media can be linearly correlated by the relationship EAB = (1.07 ± 0.13) × EAC + (2.84 ± 0.22) V. The slopes and intercepts of these equations can be correlated with the dielectric constants of the polymer film environments and the redox potentials of the reference electrodes, as modified by the surrounding electrolyte, respectively.

  16. Energy levels, transition probabilities, and electron impact excitations for La XXX

    SciTech Connect

    Zhong, J.Y. . E-mail: jyzhong@aphy.iphy.ac.cn; Zhao, G.; Zhang, J.

    2006-09-15

    energy levels, spontaneous radiative decay rates, and electron impact collision strengths are calculated for La XXX. The data refer to 107 fine-structure levels belonging to the configurations (1s{sup 2}2s{sup 2}2p{sup 6})3s{sup 2}3p{sup 6}3d{sup 10}, 3s{sup 2}3p{sup 6}3d{sup 9}4l, 3s{sup 2}3p{sup 5}3d{sup 10}4l, and 3s3p{sup 6}3d{sup 10}4l (l = s, p, d, f). The collision strengths are calculated with a 20-collision-energy grid in terms of the energy of the scattered electron between 10 and 10,000 eV by using the distorted-wave approximation. Effective collision strengths are obtained at seven electron temperatures: T {sub e} (eV) = 10, 100, 300, 500, 800, 1000, and 1500 by integrating the collision strengths over a Maxwellian electron distribution. Coupled with these atomic data, a hydrodynamic code MED103 can be used to simulate the Ni-like La X-ray laser at 8.8 nm.

  17. New odd-parity high-lying energy levels of the europium atom by resonance ionization spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakhate, S. G.; Razvi, M. A. N.; Bhale, G. L.; Ahmad, S. A.

    1996-04-01

    Odd-parity energy levels of the neutral europium atom (Eu I) have been investigated by employing both single-colour and two-colour stepwise laser excitation using the technique of resonance ionization spectroscopy in a heat-pipe thermionic diode system. Fifty-two new odd-parity energy levels of Eu I have been found in the energy region 40 575 - 43 410 0953-4075/29/8/009/img1. The J values for most of these new energy levels have been assigned unambiguously. In addition to this, 19 odd levels which were reported earlier, in the region of our present study, have also been investigated; the assignments of J values to nine of these levels have been confirmed and four levels, which had no unique J assignments, have been assigned definite J values.

  18. Low Bone Density

    MedlinePlus

    ... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

  19. The energy-level crossing behavior and quantum Fisher information in a quantum well with spin-orbit coupling

    PubMed Central

    Wang, Z. H.; Zheng, Q.; Wang, Xiaoguang; Li, Yong

    2016-01-01

    We study the energy-level crossing behavior in a two-dimensional quantum well with the Rashba and Dresselhaus spin-orbit couplings (SOCs). By mapping the SOC Hamiltonian onto an anisotropic Rabi model, we obtain the approximate ground state and its quantum Fisher information (QFI) via performing a unitary transformation. We find that the energy-level crossing can occur in the quantum well system within the available parameters rather than in cavity and circuit quantum eletrodynamics systems. Furthermore, the influence of two kinds of SOCs on the QFI is investigated and an intuitive explanation from the viewpoint of the stationary perturbation theory is given. PMID:26931762

  20. A Critical Compilation of Energy Levels, Spectral Lines, and Transition Probabilities of Singly Ionized Silver, Ag II

    PubMed Central

    Kramida, Alexander

    2013-01-01

    All available experimental measurements of the spectrum of the Ag+ ion are critically reviewed. Systematic shifts are removed from the measured wavelengths. The compiled list of critically evaluated wavelengths is used to derive a comprehensive list of energy levels with well-defined uncertainties. Eigenvector compositions and level designations are found in two alternate coupling schemes. Some of the older work is found to be incorrect. A revised value of the ionization energy, 173283(7) cm−1, equivalent to 21.4844(8) eV, is derived from the new energy levels. A set of critically evaluated transition probabilities is given. PMID:26401429

  1. Energy level alignment in polymer organic solar cells at donor-acceptor planar junction formed by electrospray vacuum deposition

    SciTech Connect

    Kim, Ji-Hoon; Hong, Jong-Am; Kwon, Dae-Gyeon; Seo, Jaewon; Park, Yongsup

    2014-04-21

    Using ultraviolet photoelectron spectroscopy (UPS), we have measured the energy level offset at the planar interface between poly(3-hexylthiophene) (P3HT) and C{sub 61}-butyric acid methylester (PCBM). Gradual deposition of PCBM onto spin-coated P3HT in high vacuum was made possible by using electrospray vacuum deposition (EVD). The UPS measurement of EVD-prepared planar interface resulted in the energy level offset of 0.91 eV between P3HT HOMO and PCBM LUMO, which is considered as the upper limit of V{sub oc} of the organic photovoltaic cells.

  2. Energy levels and far-infrared optical absorption of impurity doped semiconductor nanorings: Intense laser and electric fields effects

    NASA Astrophysics Data System (ADS)

    Barseghyan, M. G.

    2016-11-01

    The effects of electron-impurity interaction on energy levels and far-infrared absorption in semiconductor nanoring under the action of intense laser and lateral electric fields have been investigated. Numerical calculations are performed using exact diagonalization technique. It is found that the electron-impurity interaction and external fields change the energy spectrum dramatically, and also have significant influence on the absorption spectrum. Strong dependence on laser field intensity and electric field of lowest energy levels, also supported by the Coulomb interaction with impurity, is clearly revealed.

  3. Effect of Different Energy Levels of Microwave on Disinfection of Dental Stone Casts

    PubMed Central

    Robati Anaraki, Mahmood; Lotfipour, Farzaneh; Moslehifard, Elnaz; Momtaheni, Ali; Sigari, Pooyan

    2013-01-01

    Background and aims Current chemical methods may not efficiently disinfect dental stone casts. The aim of this study was to investigate if microwave irradiation is effective for disinfection of stone casts. Materials and methods In this laboratory study, three groups (n = 162) of prepared spherical stone beads as carriers with a diameter of 10 mm were inoculated by separately soaking in three broth culture media, each containing a study microorganism—Pseudomonas aeruginosa, Staphylococcus aureus or Candida albicans. Six inoculated carriers were used for every test, including irradiation in a household microwave oven at 300, 450, 600 or 900 W energy level, or soaking in 0.03%, 0.06%, 0.12%, 0.25% or 0.50% concentration of sodium hypochlorite solution, at 1, 2, or 3-minute test times. Positive and negative control groups were considered for each test. All treated carriers were then individually transferred to nutrient broth culture medium and one milliliter from each tube was cultured in nutrient agar media over night. Colony forming unit per milliliter (CFU/mL) was counted, and multi-factor ANOVA was used to analyze data (α = 0.05). Results Microwave irradiation at 600 W resulted in high-level disinfection in 3 minutes. Immersion of the stone casts in hypochlorite solution at 0.06% concentration resulted in disinfection after 2 minutes. Conclusion According to the results, high level disinfection of the stone casts can be achieved by microwave irradiation at 600 W in 3 minutes, similar to a validated chemical method. PMID:24082984

  4. Energy transfer and energy level decay processes in Tm{sup 3+}-doped tellurite glass

    SciTech Connect

    Gomes, Laercio; Lousteau, Joris; Milanese, Daniel; Scarpignato, Gerardo C.; Jackson, Stuart D.

    2012-03-15

    The primary excited state decay and energy transfer processes in singly Tm{sup 3+}-doped TeO{sub 2}:ZnO:Bi{sub 2}O{sub 3}:GeO{sub 2} (TZBG) glass relating to the {sup 3}F{sub 4}{yields}{sup 3}H{sub 6}{approx}1.85 {mu}m laser transition have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the {sup 3}H{sub 4} manifold at 794 nm, the {sup 3}H{sub 5} manifold at 1220 nm, and {sup 3}F{sub 4} manifold at 1760 nm has established that the {sup 3}H{sub 5} manifold is entirely quenched by multiphonon relaxation in tellurite glass. The luminescence from the {sup 3}H{sub 4} manifold with an emission peak at 1465 nm suffers strong suppression due to cross relaxation that populates the {sup 3}F{sub 4} level with a near quadratic dependence on the Tm{sup 3+} concentration. The {sup 3}F{sub 4} lifetime becomes longer as the Tm{sup 3+} concentration increases due to energy migration and decreases to 2.92 ms when [Tm{sup 3+}] = 4 mol. % as a result of quasi-resonant energy transfer to free OH{sup -} radicals present in the glass at concentrations between 1 x 10{sup 18} cm{sup -3} and 2 x 10{sup 18} cm{sup -3}. Judd-Ofelt theory in conjunction with absorption measurements were used to obtain the radiative lifetimes and branching ratios of the energy levels located below 25 000 cm{sup -1}. The spectroscopic parameters, the cross relaxation and Tm{sup 3+}({sup 3}F{sub 4}) {yields} OH{sup -} energy transfer rates were used in a numerical model for laser transitions emitting at 2335 nm and 1865 nm.

  5. Effect of diet energy level and genomic residual feed intake on dairy heifer performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the growth, feed intake, and feed efficiency of dairy heifers with different genomically predicted residual feed intakes (RFI), and offered diets differing in energy density. Post-bred Holstein heifers (N=128; ages 14-20 months) were blocked by initial we...

  6. Additions to the spectra and energy levels of the zinc-like ions Y X-Cd XIX

    NASA Astrophysics Data System (ADS)

    Litzén, Ulf; Hansson, Anna

    1989-10-01

    Transitions from 4p4d 1F and 3F have been identified in the spectra Y X-Cd XIX emitted from laserproduced plasmas. Energy levels have been derived, and the term structure has been studied with special emphasis on the 4s4f-4p4d configuration interaction.

  7. Energy level alignment in TiO2/metal sulfide/polymer interfaces for solar cell applications.

    PubMed

    Lindblad, Rebecka; Cappel, Ute B; O'Mahony, Flannan T F; Siegbahn, Hans; Johansson, Erik M J; Haque, Saif A; Rensmo, Håkan

    2014-08-28

    Semiconductor sensitized solar cell interfaces have been studied with photoelectron spectroscopy to understand the interfacial electronic structures. In particular, the experimental energy level alignment has been determined for complete TiO2/metal sulfide/polymer interfaces. For the metal sulfides CdS, Sb2S3 and Bi2S3 deposited from single source metal xanthate precursors, it was shown that both driving forces for electron injection into TiO2 and hole transfer to the polymer decrease for narrower bandgaps. The energy level alignment results were used in the discussion of the function of solar cells with the same metal sulfides as light absorbers. For example Sb2S3 showed the most favourable energy level alignment with 0.3 eV driving force for electron injection and 0.4 eV driving force for hole transfer and also the most efficient solar cells due to high photocurrent generation. The energy level alignment of the TiO2/Bi2S3 interface on the other hand showed no driving force for electron injection to TiO2, and the performance of the corresponding solar cell was very low.

  8. Combinatorial nuclear level-density model

    SciTech Connect

    Moller, Peter; Aberg, Sven; Uhrenhoit, Henrik; Ickhikawa, Takatoshi

    2008-01-01

    A microscopic nuclear level-density model is presented. The model is a completely combinatorial (micro-canonical) model based on the folded-Yukawa single-particle potential and includes explicit treatment of pairing, rotational and vibrational states. The microscopic character of all states enables extraction of level distribution functions with respect to pairing gaps, parity and angular momentum. The results of the model are compared to available experimental data: neutron separation energy level spacings, data on total level-density functions from the Oslo method and data on parity ratios.

  9. Quantum mechanics on a Möbius ring: Energy levels, symmetry, optical transitions, and level splitting in a magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Zehao; Ram-Mohan, L. R.

    2012-05-01

    We investigate the quantum mechanical energy levels of an electron constrained to motion on a nanoscale Möbius ring by solving the Schrödinger equation on the curved surface. The dimensions of the ring in terms of the lateral and transverse parameters {u,v} for the Möbius ring allow us to identify the quantum numbers for the levels by (nu,nv). We show that the energy levels can still be labeled using the quantum numbers of the cylindrical ring of the same dimensions. While the Hamiltonian has invariance under parity in parameter space, the rotational symmetry about any axis in configuration space is lost, so that the double degeneracy of energy levels for azimuthal quantum number nu≥1, that exists in cylindrical rings, is lifted by a small amount in the Möbius ring. The pattern of level splitting has been identified in terms of the number of twists σ to be 2nu=sσ where s is an integer. The scaling properties of the energy levels with respect to the dimensions of the ring are derived; using these properties, our numerical results which are given for a specific geometry can be extended to rings of other commensurate dimensions. The absence of rotational invariance for the Möbius ring manifests itself through the orbital angular momentum Lz not commuting with the Hamiltonian. Its expectation values are found to have nearly integral as well as half-integral values of ℏ, and its variances are small. The energy levels with half-integral azimuthal quantum numbers (nu) are also close to the approximate formula for the equivalent cylindrical ring, provided such half-integral quantum numbers are allowed for the cylindrical geometry. The Zeeman splitting of the energy levels in an external magnetic field is displayed, together with wave functions at a level anticrossing. The optical transitions between electronic states on the Möbius ring are obtained, and a table of oscillator strengths is provided. The results for energy levels for rings with multiple twists are

  10. Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sulfur-like iron, Fe XI

    SciTech Connect

    Abou El-Maaref, A.; Ahmad, Mahmoud; Allam, S.H.

    2014-05-15

    Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s{sup 2}3p{sup 4}, 3s3p{sup 5}, 3s{sup 2}3p{sup 3}3d, 3s{sup 2}3p{sup 3}4s, 3s{sup 2}3p{sup 3}4p, and 3s{sup 2}3p{sup 3}4d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit–Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term, and spin–orbit, spin–other-orbit, and spin–spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications. -- Highlights: •Accurate atomic data of iron ions are needed for identification of solar corona. •Extensive configuration interaction wavefunctions including 123 fine-structure levels have been calculated. •The relativistic effects by means of the Breit–Pauli Hamiltonian terms are incorporated. •This incorporation adjusts the energy levels, therefore the calculated values are close to experimental values.

  11. The self-consistent calculation of pseudo-molecule energy levels, construction of energy level correlation diagrams and an automated computation system for SCF-X(Alpha)-SW calculations

    NASA Technical Reports Server (NTRS)

    Schlosser, H.

    1981-01-01

    The self consistent calculation of the electronic energy levels of noble gas pseudomolecules formed when a metal surface is bombarded by noble gas ions is discussed along with the construction of energy level correlation diagrams as a function of interatomic spacing. The self consistent field x alpha scattered wave (SCF-Xalpha-SW) method is utilized. Preliminary results on the Ne-Mg system are given. An interactive x alpha programming system, implemented on the LeRC IBM 370 computer, is described in detail. This automated system makes use of special PROCDEFS (procedure definitions) to minimize the data to be entered manually at a remote terminal. Listings of the special PROCDEFS and of typical input data are given.

  12. Interplay between Self-Assembled Structures and Energy Level Alignment of Benzenediamine on Au(111) Surfaces

    NASA Astrophysics Data System (ADS)

    Li, Guo; Neaton, Jeffrey

    2015-03-01

    Using van der Waals-corrected density functional theory (DFT) calculations, we study the adsorption of benzene-diamine (BDA) molecules on Au(111) surfaces. We find that at low surface coverage, the adsorbed molecules prefer to stay isolated from each other in a monomer phase, due to the inter-molecular dipole-dipole repulsions. However, when the coverage rises above a critical value of 0.9nm-2, the adsorbed molecules aggregate into linear structures via hydrogen bonding between amine groups, consistent with recent experiments [Haxton, Zhou, Tamblyn, et al, Phys. Rev. Lett. 111, 265701 (2013)]. Moreover, we find that these linear structures at high density considerably reduces the Au work function (relative to a monomer phase). Due to reduced surface polarization effects, we estimate that the resonance energy of the highest occupied molecular orbital of the adsorbed BDA molecule relative to the Au Fermi level is significantly lower than the monomer phase by more than 0.5 eV, consistent with the experimental measurements [DellAngela, Kladnik, and Cossaro, et al., Nano Lett. 10, 2470 (2010)]. This work supported by DOE (the JCAP under Award Number DE-SC000499 and the Molecular Foundry of LBNL), and computational resources provided by NERSC.

  13. Nuclear level density: Shell-model approach

    NASA Astrophysics Data System (ADS)

    Sen'kov, Roman; Zelevinsky, Vladimir

    2016-06-01

    Knowledge of the nuclear level density is necessary for understanding various reactions, including those in the stellar environment. Usually the combinatorics of a Fermi gas plus pairing is used for finding the level density. Recently a practical algorithm avoiding diagonalization of huge matrices was developed for calculating the density of many-body nuclear energy levels with certain quantum numbers for a full shell-model Hamiltonian. The underlying physics is that of quantum chaos and intrinsic thermalization in a closed system of interacting particles. We briefly explain this algorithm and, when possible, demonstrate the agreement of the results with those derived from exact diagonalization. The resulting level density is much smoother than that coming from conventional mean-field combinatorics. We study the role of various components of residual interactions in the process of thermalization, stressing the influence of incoherent collision-like processes. The shell-model results for the traditionally used parameters are also compared with standard phenomenological approaches.

  14. Stimulated neutrino transformation with sinusoidal density profiles

    DOE PAGESBeta

    Kneller, J. P.; McLaughlin, G. C.; Patton, K. M.

    2013-03-28

    Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations where the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernovae are the one realistic possibility due to the necessity of both largemore » densities and large amplitude fluctuations. In conclusion, the comparison of numerical and analytical results of neutrino propagation through a model supernova reveals that it is possible to predict the locations and strengths of the stimulated transitions that occur.« less

  15. Stimulated neutrino transformation with sinusoidal density profiles

    SciTech Connect

    Kneller, J. P.; McLaughlin, G. C.; Patton, K. M.

    2013-03-28

    Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations where the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernovae are the one realistic possibility due to the necessity of both large densities and large amplitude fluctuations. In conclusion, the comparison of numerical and analytical results of neutrino propagation through a model supernova reveals that it is possible to predict the locations and strengths of the stimulated transitions that occur.

  16. Energy levels of GaAs/AlxGa1-xAs/AlAs spherical quantum dot with an impurity

    NASA Astrophysics Data System (ADS)

    Boz, Figen Karaca; Nisanci, Beyza; Aktas, Saban; Okan, S. Erol

    2016-11-01

    We have calculated the energy levels and the radial probability distributions of an electron with an impurity in a spherical quantum dot which is layered as GaAs/AlxGa1-xAs/AlAs. The numerical method used is the fourth-order Runge-Kutta method in the framework of the effective mass approximation. The variation of the energy levels have been calculated as functions of the radius of the GaAs sphere and the thickness of AlxGa1-xAs spherical layer considering effective mass and dielectric constant mismatches. The results have presented the importance of the geometry on the electronic properties of the spherical GaAs/AlxGa1-xAs/AlAs quantum dot.

  17. Interfacial energy level alignments between low-band-gap polymer PTB7 and indium zinc oxide anode

    NASA Astrophysics Data System (ADS)

    Shin, Dongguen; Lee, Jeihyun; Park, Soohyung; Jeong, Junkyeong; Seo, Ki-Won; Kim, Hyo-Joong; Kim, Han-Ki; Choi, Min-Jun; Chung, Kwun-Bum; Yi, Yeonjin

    2015-09-01

    The interfacial energy level alignments between poly(thieno[3,4-b]-thiophene)-co-benzodithiophene (PTB7) and indium zinc oxide (IZO) were investigated. In situ ultraviolet photoemission spectroscopy measurements were conducted with the step-by-step deposition of PTB7 on IZO substrate. All spectral changes were analyzed between each deposition step, and interfacial energy level alignments were estimated. The hole barrier of standard ultraviolet-ozone treated IZO is 0.58 eV, which is lower than the value of 1.09 eV obtained for bare IZO. The effect of barrier reduction on the hole transport was also confirmed with electrical measurements of hole-dominated devices.

  18. Correlation between the energy level structure of cerium-doped yttrium aluminum garnet and luminescent behavior at varying temperatures

    NASA Astrophysics Data System (ADS)

    Song, Zhen; Liu, Xiaolang; He, Lizhu; Liu, Q. L.

    2016-05-01

    Luminescent spectra of cerium-doped yttrium aluminum garnet are measured at varying temperatures. It is found that the two excitation peaks demonstrate a reverse trend as the temperature rises, and the breadth of the high-energy emission peak experiences an abrupt widening. These effects could be directly linked to the energy level scheme of Ce3+ under the crystal field of local symmetry. Moreover, an alternative fitting function is provided which could effectively resolve the emission curve.

  19. Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.

    PubMed

    Koput, Jacek

    2016-10-01

    The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3  = 16 state.

  20. Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.

    PubMed

    Koput, Jacek

    2016-10-01

    The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3  = 16 state. PMID:27481562

  1. Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy.

    PubMed

    Harwell, J R; Baikie, T K; Baikie, I D; Payne, J L; Ni, C; Irvine, J T S; Turnbull, G A; Samuel, I D W

    2016-07-20

    The field of organo-lead halide perovskite solar cells has been rapidly growing since their discovery in 2009. State of the art devices are now achieving efficiencies comparable to much older technologies like silicon, while utilising simple manufacturing processes and starting materials. A key parameter to consider when optimising solar cell devices or when designing new materials is the position and effects of the energy levels in the materials. We present here a comprehensive study of the energy levels present in a common structure of perovskite solar cell using an advanced macroscopic Kelvin probe and UV air photoemission setup. By constructing a detailed map of the energy levels in the system we are able to predict the importance of each layer to the open circuit voltage of the solar cell, which we then back up through measurements of the surface photovoltage of the cell under white illumination. Our results demonstrate the effectiveness of air photoemission and Kelvin probe contact potential difference measurements as a method of identifying the factors contributing to the open circuit voltage in a solar cell, as well as being an excellent way of probing the physics of new materials.

  2. Energy levels, oscillator strengths, and radiative rates for Si-like Zn XVII, Ga XVIII, Ge XIX, and As XX

    SciTech Connect

    Abou El-Maaref, A.; Allam, S.H.; El-Sherbini, Th.M.

    2014-01-15

    The energy levels, oscillator strengths, line strengths, and transition probabilities for transitions among the terms belonging to the 3s{sup 2}3p{sup 2}, 3s3p{sup 3}, 3s{sup 2}3p3d, 3s{sup 2}3p4s, 3s{sup 2}3p4p and 3s{sup 2}3p4d configurations of silicon-like ions (Zn XVII, Ga XVIII, Ge XIX, and As XX) have been calculated using the configuration-interaction code CIV3. The calculations have been carried out in the intermediate coupling scheme using the Breit–Pauli Hamiltonian. The present calculations have been compared with the available experimental data and other theoretical calculations. Most of our calculations of energy levels and oscillator strengths (in length form) show good agreement with both experimental and theoretical data. Lifetimes of the excited levels have also been calculated. -- Highlights: •We have calculated the fine-structure energy levels of Si-like Zn, Ga, Ge and As. •The calculations are performed using the configuration interaction method (CIV3). •We have calculated the oscillator strengths, line strengths and transition rates. •The wavelengths of the transitions are listed in this article. •We also have made comparisons between our data and other calculations.

  3. Position-dependent energy-level shifts of an accelerated atom in the presence of a boundary

    SciTech Connect

    Zhu Zhiying; Yu Hongwei

    2010-10-15

    We consider a uniformly accelerated atom interacting with a vacuum electromagnetic field in the presence of an infinite conducting plane boundary and calculate separately the contributions of vacuum fluctuations and radiation reaction to the atomic energy-level shift. We analyze in detail the behavior of the total energy shift in three different regimes of the distance in both the low-acceleration and high-acceleration limits. Our results show that, in general, an accelerated atom does not behave as if immersed in a thermal bath at the Unruh temperature in terms of the atomic energy-level shifts, and the effect of the acceleration on the atomic energy-level shifts may in principle become appreciable in certain circumstances, although it may not be realistic for actual experimental measurements. We also examine the effects of the acceleration on the level shifts when the acceleration is of the order of the transition frequency of the atom and we find some features which differ from what was obtained in the existing literature.

  4. Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy.

    PubMed

    Harwell, J R; Baikie, T K; Baikie, I D; Payne, J L; Ni, C; Irvine, J T S; Turnbull, G A; Samuel, I D W

    2016-07-20

    The field of organo-lead halide perovskite solar cells has been rapidly growing since their discovery in 2009. State of the art devices are now achieving efficiencies comparable to much older technologies like silicon, while utilising simple manufacturing processes and starting materials. A key parameter to consider when optimising solar cell devices or when designing new materials is the position and effects of the energy levels in the materials. We present here a comprehensive study of the energy levels present in a common structure of perovskite solar cell using an advanced macroscopic Kelvin probe and UV air photoemission setup. By constructing a detailed map of the energy levels in the system we are able to predict the importance of each layer to the open circuit voltage of the solar cell, which we then back up through measurements of the surface photovoltage of the cell under white illumination. Our results demonstrate the effectiveness of air photoemission and Kelvin probe contact potential difference measurements as a method of identifying the factors contributing to the open circuit voltage in a solar cell, as well as being an excellent way of probing the physics of new materials. PMID:27384817

  5. [Development of an optimized formulation of damask marmalade with low energy level using Taguchi methodology].

    PubMed

    Villarroel, Mario; Castro, Ruth; Junod, Julio

    2003-06-01

    The goal of this present study was the development of an optimized formula of damask marmalade low in calories applying Taguchi methodology to improve the quality of this product. The selection of this methodology lies on the fact that in real life conditions the result of an experiment frequently depends on the influence of several variables, therefore, one expedite way to solve this problem is utilizing factorial desings. The influence of acid, thickener, sweetener and aroma additives, as well as time of cooking, and possible interactions among some of them, were studied trying to get the best combination of these factors to optimize the sensorial quality of an experimental formulation of dietetic damask marmalade. An orthogonal array L8 (2(7)) was applied in this experience, as well as level average analysis was carried out according Taguchi methodology to determine the suitable working levels of the design factors previously choiced, to achieve a desirable product quality. A sensory trained panel was utilized to analyze the marmalade samples using a composite scoring test with a descriptive acuantitative scale ranging from 1 = Bad, 5 = Good. It was demonstrated that the design factors sugar/aspartame, pectin and damask aroma had a significant effect (p < 0.05) on the sensory quality of the marmalade with 82% of contribution on the response. The optimal combination result to be: citric acid 0.2%; pectin 1%; 30 g sugar/16 mg aspartame/100 g, damask aroma 0.5 ml/100 g, time of cooking 5 minutes. Regarding chemical composition, the most important results turned out to be the decrease in carbohydrate content compaired with traditional marmalade with a reduction of 56% in coloric value and also the amount of dietary fiber greater than similar commercial products. Assays of storage stability were carried out on marmalade samples submitted to different temperatures held in plastic bags of different density. Non percetible sensorial, microbiological and chemical changes

  6. Orientation dependant charge transfer at fullerene/Zn-phthalocyanine (C60/ZnPc) interface: Implications for energy level alignment and photovoltaic properties

    NASA Astrophysics Data System (ADS)

    Javaid, Saqib; Javed Akhtar, M.

    2016-08-01

    Recently, experimental results have shown that photovoltaic properties of Fullerene (C60)/Phthalocyanine based devices improve considerably as molecular orientation is changed from edge-on to face-on. In this work, we have studied the impact of molecular orientation on C60/ZnPc interfacial properties, particularly focusing on experimentally observed face-on and edge-on configuration, using density functional theory based simulations. The results show that the interfacial electronic properties are strongly anisotropic: direction of charge transfer and interface dipole fluctuates as molecular orientation is switched. As a result of orientation dependant interface dipole, difference between acceptor LUMO and donor HOMO increases as the orientation is changed from edge-on to face-on, suggesting a consequent increase in open circuit voltage (VOC). Moreover, adsorption and electronic properties indicate that the interfacial interactions are much stronger in the face-on configuration which should further facilitate the charge-separation process. These findings elucidate the energy level alignment at C60/ZnPc interface and help to identify interface dipole as the origin of the orientation dependence of VOC.

  7. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    PubMed

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated.

  8. Positronium energy levels at order m α7 : Product contributions in the two-photon-annihilation channel

    NASA Astrophysics Data System (ADS)

    Adkins, Gregory S.; Tran, Lam M.; Wang, Ruihan

    2016-05-01

    Ongoing improvements in the measurement of positronium transition intervals motivate the calculation of the O (m α7) corrections to these intervals. In this work we focus on corrections to the spin-singlet parapositronium energies involving virtual annihilation to two photons in an intermediate state. We have evaluated all contributions to the positronium S -state energy levels that can be written as the product of a one-loop correction on one side of the annihilation event and another one-loop correction on the other side. These effects contribute Δ E =-0.561971 (25 ) m α7/π3 to the parapositronium ground-state energy.

  9. The effect of fibre amount, energy level and viscosity of beverages containing oat fibre supplement on perceived satiety

    PubMed Central

    Lyly, Marika; Ohls, Nora; Lähteenmäki, Liisa; Salmenkallio-Marttila, Marjatta; Liukkonen, Kirsi-Helena; Karhunen, Leila; Poutanen, Kaisa

    2010-01-01

    Background Soluble fibre has been proposed to suppress appetite-related perceptions and it could thus contribute favourably to the regulation of energy intake and the increasing obesity problem. Objective To investigate the effect of an oat ingredient rich in β-glucan on perceived satiety at different dietary fibre (DF) concentrations, energy levels and viscosity levels. Design A total of 29 healthy volunteers, age 19–39, mean BMI 23.2 kg/m2 participated in this study. Measurement of subjective perceptions (satiety, fullness, hunger, desire to eat something/the sample food and thirst) was performed during a 180-min period after ingestion of the sample. There were altogether six samples: two beverages without fibre at energy levels 700 and 1,400 kJ; two beverages containing 5 or 10 g oat DF (2.5 and 5 g oat β-glucan, respectively) at energy level 700 kJ, one beverage containing 10 g oat DF/1,400 kJ and one beverage containing 10 g enzymatically treated oat DF with low viscosity at energy level 700 kJ. Each beverage portion weighted 300 g. The order of the samples was randomised for each subject and evaluated during six separate days. The results are reported in three sets of samples: ‘fibre’, ‘energy’ and ‘viscosity’. Results In the fibre set, the beverages containing 5 or 10 g of fibre had a larger area under curve (AUC) for perceived satiety and smaller AUC for hunger compared to the beverage without fibre, but no significant dose–response relationship was detected. Increasing the energy content from 700 to 1,400 kJ in the energy set did not affect the satiety-related perceptions. In the viscosity set, the beverage with low-viscosity β-glucan increased satiety-related perceptions from no fibre containing beverage, but less compared to the beverage with the same amount of fibre and higher viscosity. Conclusions Addition of an oat ingredient rich in β-glucan and high viscosity of beverages enhance post-meal satiety induced by beverages. The

  10. Energy levels, Auger branching ratios, and radiative rates of the core-excited states of B-like carbon

    SciTech Connect

    Sun Yan; Gou Bingcong; Chen Feng

    2011-09-28

    Energy levels, Auger branching ratios, and radiative rates of the core-excited states of B-like carbon are calculated by the saddle-point variation and saddle-point complex-rotation methods. Relativistic and mass polarization corrections are included using first-order perturbation theory. Calculated Auger channel energies and branching ratios are used to identify high-resolution Auger spectrum in the 300-keV C{sup +}{yields} CH{sub 4} collision experiment. It is found that Auger decay of these five-electron core-excited states gives significant contributions to Auger spectrum in the range of 238-280 eV.

  11. Ab initio ground-state potential energy function and vibration-rotation energy levels of imidogen, NH.

    PubMed

    Koput, Jacek

    2015-06-30

    The accurate ground-state potential energy function of imidogen, NH, has been determined from ab initio calculations using the multireference averaged coupled-pair functional (MR-ACPF) method in conjunction with the correlation-consistent core-valence basis sets up to octuple-zeta quality. The importance of several effects, including electron correlation beyond the MR-ACPF level of approximation, the scalar relativistic, adiabatic, and nonadiabatic corrections were discussed. Along with the large one-particle basis set, all of these effects were found to be crucial to attain "spectroscopic" accuracy of the theoretical predictions of vibration-rotation energy levels of NH.

  12. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2011-11-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  13. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2012-01-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  14. Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2

    NASA Astrophysics Data System (ADS)

    Gruber, John B.; Sardar, Dhiraj K.; Russell, Charles C.; Yow, Raylon M.; Zandi, Bahram; Kokanyan, Edvard P.

    2003-12-01

    Absorption and fluorescence spectra of Er3+(4f11) in crystals of NaBi(WO4)2 (NBW) are reported at temperatures between 15 K and room temperature. The absorption spectra include the details of the crystal-field splitting of 11 multiplet manifolds, 2S+1LJ of Er3+(4f11), spanning the wavelength range between 350 nm and 1550 nm. The crystal-field splitting of the ground-state 4I15/2, is obtained from an analysis of the fluorescence spectrum, 4S3/2→4I15/2. Spectra are characterized by inhomogeneous broadening due to the disordered crystal structure in which different valency cations, Na+ and Bi3+, statistically fill the S4 symmetry sites. The Er3+ ions likely replace the Bi3+ ions in these sites. A quasi-center model has been chosen to interpret the crystal-field splitting of each manifold, using D2d rather than S4 symmetry as the site for the rare-earth ion in the lattice. To test the feasibility of the model, the splitting of the energy levels of Nd3+ in NBW was carried out first and compared with experimental levels reported in literature. A least-squares fitting analysis between 26 calculated-to-observed energy (Stark) levels gave a root-mean-square (rms) deviation of 8 cm-1 for the 4IJ and 4F3/2 multiplet manifolds of Nd3+ in NBW. Using the phenomenological lattice-sum parameters, Anm, obtained from the analysis of the Nd3+ energy levels, we predicted an initial set of crystal-field parameters, Bnm, for Er3+. With only a modest fitting of the multiplet centroids, these Bnm predict the observed splitting in the Er3+ spectra remarkably well. In a fitting of the energy levels in which both the Bnm and centroids are allowed to vary, we obtained a rms deviation of 6 cm-1 for 57 calculated-to-observed Stark levels. The results suggest that the quasi-center model has merit when used to calculate the crystal-field splitting of the energy levels of the trivalent rare-earth ions in crystal hosts having a disordered structure.

  15. Full formula for heavy quarkonium energy levels at next-to-next-to-next-to-leading order

    NASA Astrophysics Data System (ADS)

    Kiyo, Y.; Sumino, Y.

    2014-12-01

    We derive a full formula for the energy level of a heavy quarkonium state identified by the quantum numbers n, ℓ, s and j, up to O (αs5m) and O (αs5mlog ⁡αs) in perturbative QCD. The QCD Bethe logarithm is given in a one-parameter integral form. The rest of the formula is given as a combination of rational numbers, transcendental numbers (π, ζ (3), ζ (5)) and finite sums (besides the 3-loop constant abar3 of the static potential whose full analytic form is still unknown). A derivation of the formula is given.

  16. MULTIPLE THICKNESS TIMES DENSITY GAMMA GAGE

    DOEpatents

    Cherry, N.H.

    1962-07-24

    A device was developed for measuring simultaneously the thicknesses of two dissimilar materials superimposed on each other, such as coating of one material on another. The apparatus utilizes a double gamma radiation source producing radiation in two narrow band energy levels. The different materials attenuate the two bands of energy unequally with the result that a composite signal is received which can be analyzed to separate out the components due to the differing materials and indicate the thickness or densities of the two layers. (AEC)

  17. Interplay between Energy-Level Position and Charging Effect of Manganese Phthalocyanines on an Atomically Thin Insulator.

    PubMed

    Liu, Liwei; Dienel, Thomas; Widmer, Roland; Gröning, Oliver

    2015-10-27

    Understanding the energy-level alignment and charge transfer of organic molecules at large bandgap semiconductors is of crucial importance to optimize device performance in organic electronics. We have studied submonolayer coverage of manganese phthalocyanine (MnPc) on hexagonal boron nitride (h-BN) on Rh(111) as a model system by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The adsorbed molecules show three distinctly different bias-dependent topographic signatures, which depend on their adsorption positions on the h-BN. Among these three types of MnPc, one shows pronounced charging because of the proximity of the highest occupied molecular orbital (HOMO) to the Fermi level on the decoupling h-BN substrate. The charging of the MnPc from its neutral to the MnPc(+) state leads to a down shift of the Mn 3d-related orbital by 840 meV as determined from the difference in energy position between high- and low-bias charging. We find that the charging field is linearly related to the HOMO position with respect to the Fermi level, with a clear correlation to the adsorption orientations of the MnPc. Our results show how critically energy level alignment and field-induced charge transfer process can depend on adsorption configurations, even on an apparently low-interacting substrate like metal supported monolayer h-BN. PMID:26390030

  18. Calculation of rotation-vibration energy levels of the ammonia molecule based on an ab initio potential energy surface

    NASA Astrophysics Data System (ADS)

    Polyansky, Oleg L.; Ovsyannikov, Roman I.; Kyuberis, Aleksandra A.; Lodi, Lorenzo; Tennyson, Jonathan; Yachmenev, Andrey; Yurchenko, Sergei N.; Zobov, Nikolai F.

    2016-09-01

    An ab initio potential energy surface (PES) for gas-phase ammonia NH3 has been computed using the methodology pioneered for water (Polyansky et al., 2013). Multireference configuration interaction calculations are performed at about 50 000 points using the aug-cc-pCVQZ and aug-cc-pCV5Z basis sets and basis set extrapolation. Relativistic and adiabatic surfaces are also computed. The points are fitted to a suitable analytical form, producing the most accurate ab initio PES for this molecule available. The rotation-vibration energy levels are computed using nuclear motion program TROVE in both linearised and curvilinear coordinates. Better convergence is obtained using curvilinear coordinates. Our results are used to assign the visible spectrum of 14NH3 recorded by Coy and Lehmann (1986). Rotation-vibration energy levels for the isotopologues NH2D, NHD2, ND3 and 15NH3 are also given. An ab initio value for the dissociation energy D0 of 14NH3 is also presented.

  19. Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers.

    PubMed

    Yao, Huifeng; Zhang, Hao; Ye, Long; Zhao, Wenchao; Zhang, Shaoqing; Hou, Jianhui

    2016-02-17

    Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers.

  20. New odd-parity energy levels of europium atoms in the 43 200-45 000 cm-1 region by laser photoionization spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakhate, S. G.; Razvi, M. A. N.; Ahmad, S. A.

    2000-01-01

    Odd-parity energy levels of europium atoms (Eu I) have been investigated by employing single-colour and two-colour stepwise resonance ionization spectroscopy techniques with a heat-pipe oven for metal vapour containment and a thermionic diode for ion detection. Eighty-two new odd-parity energy levels of Eu I have been found in the energy region 43 200-45 000 cm-1 . The J quantum numbers for all these newly discovered energy levels have been uniquely assigned. In addition to this, some of the energy levels previously reported by us and assigned more than one J quantum number have been re-investigated and unique J quantum numbers for these levels have been determined.

  1. Energy levels of very short-period (GaAs) sub n -(AlAs) sub n superlattices

    SciTech Connect

    Ge, W.; Sturge, M.D.; Schmidt, W.D. ); Pfeiffer, L.N.; West, K.W. )

    1990-07-02

    The energy levels of very short-period (GaAs){sub {ital n}}-(AlAs){sub {ital n}} superlattices ({ital n}{le}4) were investigated by photoluminescence (PL). The results show that these superlattices are type II but the lowest conduction bands are {ital X}{sub {ital x},{ital y}} for {ital n}{le}3 and {ital X}{sub {ital z}} for {ital n}=4, respectively. (Here {ital X}{sub {ital z}} is the valley with {bold k} parallel to the growth axis.) In both cases the {ital X} valleys are very close to each other. PL decay, PL excitation, and PL under uniaxial stress confirm this identification. Al{sub 0.5}Ga{sub 0.5}As shows very different behavior, showing that even for {ital n}=1 our samples are true superlattices.

  2. SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF C-LIKE IONS WITH Z = 13-36

    SciTech Connect

    Wang, K.; Li, D. F.; Liu, H. T.; Han, X. Y.; Duan, B.; Li, C. Y.; Li, J. G.; Yan, J.; Guo, X. L.; Chen, C. Y.

    2015-01-01

    Based on systematic calculations using a combined relativistic configuration interaction and a many-body perturbation theory (MBPT) approach, we provide a complete and consistent data set for 46 levels belonging to the 2s {sup 2}2p {sup 2}, 2s2p {sup 3}, 2p {sup 4}, 2s {sup 2}2p3s, 2s {sup 2}2p3p, and 2s {sup 2}2p3d configurations in C-like ions with 13 ≤ Z ≤ 36. The data set includes energy levels as well as electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition properties. Extensive comparisons with available observed and calculated results are made and indicate that the present MBPT calculations are highly accurate. The present data set can be used reliably for many purposes, such as the line identification of observed spectra, and modeling and diagnostics of astrophysical and fusion plasmas.

  3. Modeling of trap-assisted tunneling on performance of charge trapping memory with consideration of trap position and energy level

    NASA Astrophysics Data System (ADS)

    Lun, Zhi-Yuan; Li, Yun; Zhao, Kai; Du, Gang; Liu, Xiao-Yan; Wang, Yi

    2016-08-01

    In this work, the trap-assisted tunneling (TAT) mechanism is modeled as a two-step physical process for charge trapping memory (CTM). The influence of the TAT mechanism on CTM performance is investigated in consideration of various trap positions and energy levels. For the simulated CTM structure, simulation results indicate that the positions of oxide traps related to the maximum TAT current contribution shift towards the substrate interface and charge storage layer interface during time evolutions in programming and retention operations, respectively. Lower programming voltage and retention operations under higher temperature are found to be more sensitive to tunneling oxide degradation. Project supported by the National Natural Science Foundation of China (Grant Nos. 61404005, 61421005, and 91434201).

  4. The interplay between interface structure, energy level alignment and chemical bonding strength at organic-metal interfaces.

    PubMed

    Willenbockel, M; Lüftner, D; Stadtmüller, B; Koller, G; Kumpf, C; Soubatch, S; Puschnig, P; Ramsey, M G; Tautz, F S

    2015-01-21

    What do energy level alignments at metal-organic interfaces reveal about the metal-molecule bonding strength? Is it permissible to take vertical adsorption heights as indicators of bonding strengths? In this paper we analyse 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on the three canonical low index Ag surfaces to provide exemplary answers to these questions. Specifically, we employ angular resolved photoemission spectroscopy for a systematic study of the energy level alignments of the two uppermost frontier states in ordered monolayer phases of PTCDA. Data are analysed using the orbital tomography approach. This allows the unambiguous identification of the orbital character of these states, and also the discrimination between inequivalent species. Combining this experimental information with DFT calculations and the generic Newns-Anderson chemisorption model, we analyse the alignments of highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) with respect to the vacuum levels of bare and molecule-covered surfaces. This reveals clear differences between the two frontier states. In particular, on all surfaces the LUMO is subject to considerable bond stabilization through the interaction between the molecular π-electron system and the metal, as a consequence of which it also becomes occupied. Moreover, we observe a larger bond stabilization for the more open surfaces. Most importantly, our analysis shows that both the orbital binding energies of the LUMO and the overall adsorption heights of the molecule are linked to the strength of the chemical interaction between the molecular π-electron system and the metal, in the sense that stronger bonding leads to shorter adsorption heights and larger orbital binding energies. PMID:25475998

  5. Ionization energies of W I-LXXIV and critical compilation of spectra and energy levels of Ga I-XXX

    NASA Astrophysics Data System (ADS)

    Kramida, Alexander; Reader, Joseph

    2006-05-01

    Both tungsten and gallium are important materials for fusion energy research. In this work, a semi-empirical method is used to determine ionization energies (IE) of multiply charged W ions [A.E. Kramida, J. Reader, Ionization Energies of Tungsten Ions: W^2+ through W^71+, At. Data Nucl. Data Tables, 2006, in press]. The method is based on Hartree-Fock calculations of electron binding energies with empirical scale factors. Relative uncertainties vary from 1.7 % for W III^ to 0.015 % for W LXXII. Combined with previously known experimental or theoretical IE values for W I-II and LXXIII-LXXIV, these new semiempirical results allow us to build a complete table of IEs of tungsten in all stages of ionization. For gallium, all available experimental data on wavelengths and energy levels are critically compiled and evaluated [T. Shirai, J. Reader, A.E. Kramida, J. Sugar, Spectral Data for Gallium: Ga I through Ga XXXI, J. Phys. Chem. Ref. Data, 2006, in press]. Such data exist for spectra Ga I-VII, XIII-XXVI, and XXX. For Li-like Ga XXIX through H-like Ga XXXI, theoretical data on energy levels and line wavelengths are compiled. For Ga I-III, XV-XX, XXIII-XXVI, and XXX, radiative transition probabilities are included where available. The ground state configuration and term and a value of IE are included for each ion. This work was supported in part by the Office of Fusion Energy Sciences of the U. S. Department of Energy.

  6. Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2007-03-27

    Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

  7. Production Density Diffusion Equation Propagation and Production

    NASA Astrophysics Data System (ADS)

    Shirai, Kenji; Amano, Yoshinori

    When we call the production flow to transition elements in the next step in the process of product manufactured one, the production flow is considered to be displaced in the direction of the unit production density. Density and production, as captured from different perspectives, also said production costs per unit of production. However, it is assumed that contributed to the production cost of manufacturing 100 percent. They may not correspond to the physical propagation conditions after each step of the production density, the equations governing the manufacturing process, which is intended to be represented by a single diffusion equation. We can also apply the concept of energy levels in statistical mechanics, production density function, in other words, in statistical mechanics “place” that if you use the world of manufacturing and production term. If the free energy in this production (potential) that are consuming the substance is nothing but the entropy production. That is, productivity is defined as the entropy production has to be. Normally, when we increase the number of production units, the product nears completion at year-end number of units completed and will aim to be delivered to the contractor from the turnover order. However, if you stop at any number of units, that will increase production density over time. Thus, the diffusion does not proceed from that would be irreversible. In other words, the congestion will occur in production. This fact and to report the results of analysis based on real data.

  8. Reexamination of the Energy Levels of 15F by 14O + 1H ElasticResonance Scattering with BEARS

    SciTech Connect

    Guo, F.Q.; Powell, J.; Lee, D.W.; Leitner, D.; McMahan, M.A.; Moltz, D.M.; O'Neil, J.P.; Perajarvi, K.; Phair, L.; Ramsey, C.A.; Xu,X.J.; Cerny, Joseph

    2005-05-30

    The energy levels of 15F have been measured by the p(14O,p)14O reaction. The 120 MeV 14O radioactive ion beam was produced by the BEARS coupled cyclotron system at an intensity averaging 1x104 particles/second on target. Energy calibration was obtained using resonances from the p(14N,p)14N reaction. The two lowest resonances in 15F were fitted with an R-matrix calculation. The fit to the ground state had Jp = 1/2+ at 1.23+-0.05 MeV (width 0.5-0.84 MeV), and the first excited state was Jp=5/2+ at 2.81+-0.02 MeV (width 0.30+-0.06 MeV), both relative to the mass-energy of the proton and 14O. The 15F ground state energy supports the disappearance of the Z=8 proton magic number for odd Z, Tz=-3/2 nuclei.

  9. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibault; Nikitin, Andrei; Rey, Michaël; Szalay, Péter G.; Tyuterev, Vladimir G.

    2014-09-01

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C2H4 obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C2H4 molecule was obtained with a RMS(Obs.-Calc.) deviation of 2.7 cm-1 for fundamental bands centers and 5.9 cm-1 for vibrational bands up to 7800 cm-1. Large scale vibrational and rotational calculations for 12C2H4, 13C2H4, and 12C2D4 isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm-1 are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of 13C2H4 and 12C2D4 and rovibrational levels of 12C2H4.

  10. Impact of MoO3 interlayer on the energy level alignment of pentacene-C60 heterostructure.

    PubMed

    Zou, Ye; Mao, Hongying; Meng, Qing; Zhu, Daoben

    2016-02-28

    Using in situ ultraviolet photoelectron spectroscopy, the electronic structure evolutions at the interface between pentacene and fullerene (C60), a classical organic donor-acceptor heterostructure in organic electronic devices, on indium-tin oxide (ITO) and MoO3 modified ITO substrates have been investigated. The insertion of a thin layer MoO3 has a significant impact on the interfacial energy level alignment of pentacene-C60 heterostructure. For the deposition of C60 on pentacene, the energy difference between the highest occupied molecular orbital of donor and the lowest unoccupied molecular orbital of acceptor (HOMO(D)-LUMO(A)) offset of C60/pentacene heterostructure increased from 0.86 eV to 1.54 eV after the insertion of a thin layer MoO3 on ITO. In the inverted heterostructrure where pentacene was deposited on C60, the HOMO(D)-LUMO(A) offset of pentacene/C60 heterostructure increased from 1.32 to 2.20 eV after MoO3 modification on ITO. The significant difference of HOMO(D)-LUMO(A) offset shows the feasibility to optimize organic electronic device performance through interfacial engineering approaches, such as the insertion of a thin layer high work function MoO3 films. PMID:26931717

  11. Hydrogen passivation of deep energy levels at the interfacial grain boundary in (110)/(100) bonded silicon wafers

    NASA Astrophysics Data System (ADS)

    Park, Yongkook; Lu, Jinggang; Rozgonyi, George

    2009-01-01

    This letter evaluates the density of grain boundary (GB) states before and after hydrogenation by J-V, C-V, and capacitance transient methods using gold/direct silicon-bonded (DSB) (110) thin silicon top layer/(100) silicon substrate junctions. The GB potential energy barrier in thermal equilibrium was reduced by 70 meV from 0.46 eV (before hydrogenation) to 0.39 eV (after hydrogen treatment). Whereas the clean sample had a density of GB states of ˜6×1012 cm-2 eV-1 in the range of Ev+0.54-0.64 eV, hydrogenation reduced the density of GB states to ˜9×1011 cm-2 eV-1 in the range of Ev+0.56-0.61 eV, which is about a sevenfold reduction from that of the clean sample.

  12. Accurate Potential Energy Surface, Rovibrational Energy Levels, and Transitions of Ammonia C_{3v} Isotopologues: ^{14}NH_3, ^{15}NH_3, ^{14}ND_3 and ^{14}NT_3

    NASA Astrophysics Data System (ADS)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2009-06-01

    A further refined, global potential energy surface (PES) is computed for the C_{3v} symmetry isotopologues of ammonia, including ^{14}NH_3, ^{15}NH_3, ^{14}ND_3 and ^{14}NT_3. The refinement procedure was similar to that used in our previously reported PES, but now extends to higher J energy levels and other isotopologues. Both the diagonal Born-Oppenheimer correction and the non-adiabatic correction were included. J=0-6 rovibrational energy levels and transition frequencies of ^{14}NH_3 computed on this PES are in excellent agreement with HITRAN data. Statistics on nearly 4100 transitions and more than 1000 energy levels demonstrate the accuracy achieved by the state-of-the-art "Best Theory + Experiment" strategy. Most transition frequencies are of ±0.01-0.02 cm^{-1} accuracy. Similar accuracy has been found on ^{15}NH_3 J=0-3 rovibrational energy levels. Several transitions and energy levels in HITRAN have been identified as unreliable or suspicious, and some have been re-assigned. For ^{14}ND_3 and ^{14}NT_3, J=0-3 calculations have been performed. Agreement for pure rotation-inversion transitions is nearly perfect, with more reliable energy levels presented. On the other hand, our J=0 results suggest a re-analysis on the ^{14}ND_3 ν_1 band origin is needed. Finally, we will discuss possible future refinements leading to an even better final PES for Ammonia. X. Huang, D.W. Schwenke, and T.J. Lee, J. Chem. Phys. 129, 214304 (2008).

  13. Energy level of the Si-related DX-center in (AlyGa1-y)1-xInxAs

    NASA Astrophysics Data System (ADS)

    Heckelmann, Stefan; Lackner, David; Bett, Andreas W.

    2015-03-01

    For the quaternary material (AlyGa1-y)1-xInxAs, the energy level of the silicon-related deep electron trap known as the DX-center is calculated. In addition, the composition range y(x) is derived, for which the silicon-related DX-center level is below the conduction band minimum and thus electronically active. Eventually, the result of the calculation is compared with available measurement data, revealing good agreement regarding the composition when the DX-center energy level crosses the conduction band minimum.

  14. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    SciTech Connect

    Delahaye, Thibault Rey, Michaël Tyuterev, Vladimir G.; Nikitin, Andrei; Szalay, Péter G.

    2014-09-14

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C{sub 2}H{sub 4} obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C{sub 2}H{sub 4} molecule was obtained with a RMS(Obs.–Calc.) deviation of 2.7 cm{sup −1} for fundamental bands centers and 5.9 cm{sup −1} for vibrational bands up to 7800 cm{sup −1}. Large scale vibrational and rotational calculations for {sup 12}C{sub 2}H{sub 4}, {sup 13}C{sub 2}H{sub 4}, and {sup 12}C{sub 2}D{sub 4} isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm{sup −1} are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of {sup 13}C{sub 2}H{sub 4} and {sup 12}C{sub 2}D{sub 4} and rovibrational levels of {sup 12}C{sub 2}H{sub 4}.

  15. Application of the generalized Euler series transformation for calculation of vibration-rotation energy levels of diatomic molecules

    NASA Astrophysics Data System (ADS)

    Kruglova, T. V.

    2004-01-01

    The detailed spectroscope information about highly excited molecules and radicals such us as H+3, H2, HI, H2O, CH2 is needed for a number of applications in the field of laser physics, astrophysics and chemistry. Studies of highly excited molecular vibration-rotation states face several problems connected with slowly convergence or even divergences of perturbation expansions. The physical reason for a perturbation expansion divergence is the large amplitude motion and strong vibration-rotation coupling. In this case one needs to use the special method of series summation. There were a number of papers devoted to this problem: papers 1-10 in the reference list are only example of studies on this topic. The present report is aimed at the application of GET method (Generalized Euler Transformation) to the diatomic molecule. Energy levels of a diatomic molecule is usually represented as Dunham series on rotational J(J+1) and vibrational (V+1/2) quantum numbers (within the perturbation approach). However, perturbation theory is not applicable for highly excited vibration-rotation states because the perturbation expansion in this case becomes divergent. As a consequence one need to use special method for the series summation. The Generalized Euler Transformation (GET) is known to be efficient method for summing of slowly convergent series, it was already used for solving of several quantum problems Refs.13 and 14. In this report the results of Euler transformation of diatomic molecule Dunham series are presented. It is shown that Dunham power series can be represented of functional series that is equivalent to its partial summation. It is also shown that transformed series has the butter convergent properties, than the initial series.

  16. Expression of Arabidopsis FCS-Like Zinc finger genes is differentially regulated by sugars, cellular energy level, and abiotic stress

    PubMed Central

    Jamsheer K, Muhammed; Laxmi, Ashverya

    2015-01-01

    Cellular energy status is an important regulator of plant growth, development, and stress mitigation. Environmental stresses ultimately lead to energy deficit in the cell which activates the SNF1-RELATED KINASE 1 (SnRK1) signaling cascade which eventually triggering a massive reprogramming of transcription to enable the plant to survive under low-energy conditions. The role of Arabidopsis thaliana FCS-Like Zinc finger (FLZ) gene family in energy and stress signaling is recently come to highlight after their interaction with kinase subunits of SnRK1 were identified. In a detailed expression analysis in different sugars, energy starvation, and replenishment series, we identified that the expression of most of the FLZ genes is differentially modulated by cellular energy level. It was found that FLZ gene family contains genes which are both positively and negatively regulated by energy deficit as well as energy-rich conditions. Genetic and pharmacological studies identified the role of HEXOKINASE 1- dependent and energy signaling pathways in the sugar-induced expression of FLZ genes. Further, these genes were also found to be highly responsive to different stresses as well as abscisic acid. In over-expression of kinase subunit of SnRK1, FLZ genes were found to be differentially regulated in accordance with their response toward energy fluctuation suggesting that these genes may work downstream to the established SnRK1 signaling under low-energy stress. Taken together, the present study provides a conceptual framework for further studies related to SnRK1-FLZ interaction in relation to sugar and energy signaling and stress response. PMID:26442059

  17. Density perturbation theory

    SciTech Connect

    Palenik, Mark C.; Dunlap, Brett I.

    2015-07-28

    Despite the fundamental importance of electron density in density functional theory, perturbations are still usually dealt with using Hartree-Fock-like orbital equations known as coupled-perturbed Kohn-Sham (CPKS). As an alternative, we develop a perturbation theory that solves for the perturbed density directly, removing the need for CPKS. This replaces CPKS with a true Hohenberg-Kohn density perturbation theory. In CPKS, the perturbed density is found in the basis of products of occupied and virtual orbitals, which becomes ever more over-complete as the size of the orbital basis set increases. In our method, the perturbation to the density is expanded in terms of a series of density basis functions and found directly. It is possible to solve for the density in such a way that it makes the total energy stationary even if the density basis is incomplete.

  18. Additions to the spectrum and energy levels and a critical compilation of helium-like and hydrogen-like boron, B IV and B V

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.; Ryabtsev, A. N.; Ekberg, J. O.; Kink, I.; Mannervik, S.; Martinson, I.

    2008-08-01

    Using beam-foil spectroscopy, we have observed several new lines in the B IV and B V spectra. This experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. We have also critically evaluated all previous and recent experimental and theoretical data for these spectra. Complete data on wavelengths and energy levels based on this analysis are tabulated.

  19. Investigation and application of quantitative relationship between sp energy levels of Bi{sup 3+} ion and host lattice

    SciTech Connect

    Wang Lili; Sun Qiang; Liu Qingzhi; Shi Jinsheng

    2012-07-15

    Information on {sup 1}S{sub 0}-{sup 3}P{sub 1} (A band) and {sup 1}S{sub 0}-{sup 1}P{sub 1} (C band) transition energy of Bi{sup 3+} ion in dozens of different compounds has been gathered and analyzed. With the use of the dielectric theory of the chemical bond for complex crystals, relationships between A and C absorption band and environmental factor h{sub e} were established: E{sub A}=2.972+6.206exp (-h{sub e}/0.551); E{sub C}=3.236+10.924exp (-h{sub e}/0.644). For Bi{sup 3+} doped hosts with known structure and refractive index, it is possible to predict Bi{sup 3+} energy level position with an good accuracy of typically {+-}0.51 eV using the two relationships. Moreover, a direct relationship between A and C band was deduced: E{sub C}=3.236+2.290(E{sub A}-2.972){sup 0.856}. Thus a very simple method to predict C band position was proposed. This work will be of great help to understand spectroscopy of Bi{sup 3+} and will be useful for developing new PDP, LED and mercury-free fluorescent lamp phosphors. - Graphical abstract: This figure shows relationship between positions of A band and C band of Bi{sup 3+} ion and environmental factor h{sub e} of host. It establishes the relation between macroscopical spectroscopy of Bi{sup 3+} ion and microcosmic structure of the hosts. Highlights: Black-Right-Pointing-Pointer Relationships between A, C absorption band and environmental factor h{sub e} were established. Black-Right-Pointing-Pointer A direct relation between A and C band was deduced and an easier method to predict C band was given. Black-Right-Pointing-Pointer Positions of C band of Bi{sup 3+} ion in some compounds were predicted using our formula.

  20. Optical decoherence and energy level structure of 0.1%Tm3+:LiNbO3

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Thiel, C. W.; Cone, R. L.

    2012-04-01

    We report the energy level structure of the 3H6 and 3H4 multiplets for Tm3+ doped congruent LiNbO3, as well as the decoherence properties and their temperature dependencies for the 3H6(1)↔3H4(1a) transition at 794 nm. It is shown that this material provides very significant improvements in bandwidth, time-bandwidth product, and sensitivity for spatial-spectral holographic signal processing devices and quantum memories based on spectral hole burning. The available signal processing bandwidth for 0.1%Tm3+:LiNbO3 is 300 GHz versus 20 GHz for Tm3+YAG. The peak absorption coefficient for 0.1%Tm3+:LiNbO3 is 15 cm-1 at 794.5 nm compared with 1.7 cm-1 for 0.1%Tm:YAG at 793 nm, and the total absorption strength is eighty times stronger. The oscillator strength for Tm3+:LiNbO3 is about twenty-five times larger than that for Tm3+:YAG, making the material five times more sensitive for processing high-bandwidth analog signals. The homogeneous linewidth, which determines processing time or spectrum analyzer resolution, is 30 kHz at 1.6 K and 350 kHz at 6 K, as measured by photon echoes. Those values establish potential time-bandwidth products of 107 and 7 ×105, respectively. The temperature dependence of the homogeneous linewidth was explained by observation of a 7.8 cm-1 crystal field level in the ground multiplet and direct phonon coupling. The excited state 3H4 lifetime T1 is 152 μs and the bottleneck lifetime of the lowest 3F4 level is 7 ms from photon echo measurements. These factors combine to provide a surprisingly large increase in key parameters that determine material performance for spatial-spectral holography, quantum information, and other spectral hole burning applications.

  1. IUPAC critical evaluation of the rotational-vibrational spectra of water vapor, Part III: Energy levels and transition wavenumbers for H216O

    NASA Astrophysics Data System (ADS)

    Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Al Derzi, Afaf R.; Fábri, Csaba; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Lodi, Lorenzo; Mizus, Irina I.

    2013-03-01

    This is the third of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, and energy levels, with associated critically reviewed labels and uncertainties, for all the main isotopologues of water. This paper presents experimental line positions, experimental-quality energy levels, and validated labels for rotational-vibrational transitions of the most abundant isotopologue of water, H216O. The latest version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) line-inversion procedure is used to determine the rovibrational energy levels of the electronic ground state of H216O from experimentally measured lines, together with their self-consistent uncertainties, for the spectral region up to the first dissociation limit. The spectroscopic network of H216O containstwo components, an ortho (o) and a para (p) one. For o-H216O and p-H216O, experimentally measured, assigned, and labeled transitions were analyzed from more than 100 sources. The measured lines come from one-photon spectra recorded at room temperature in absorption, from hot samples with temperatures up to 3000 K recorded in emission, and from multiresonance excitation spectra which sample levels up to dissociation. The total number of transitions considered is 184 667 of which 182 156 are validated: 68 027 between para states and 114 129 ortho ones. These transitions give rise to 18 486 validated energy levels, of which 10 446 and 8040 belong to o-H216O and p-H216O, respectively. The energy levels, including their labeling with approximate normal-mode and rigid-rotor quantum numbers, have been checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators as well as against previous compilations of energy levels. The extensive list of MARVEL lines and levels obtained are deposited in the supplementary data of this paper, as well as in a distributed information system

  2. Energy level alignment of self-assembled linear chains of benzenediamine on Au(111) from first principles

    NASA Astrophysics Data System (ADS)

    Li, Guo; Rangel, Tonatiuh; Liu, Zhen-Fei; Cooper, Valentino R.; Neaton, Jeffrey B.

    2016-03-01

    Using density functional theory (DFT) with a van der Waals density functional, we calculate the adsorption energetics and geometry of benzenediamine (BDA) molecules on Au(111) surfaces. Our results demonstrate that the reported self-assembled linear chain structure of BDA, stabilized via hydrogen bonds between amine groups, is energetically favored over previously studied monomeric phases. Moreover, using a model, which includes nonlocal polarization effects from the substrate and the neighboring molecules and incorporates many-body perturbation theory calculations within the GW approximation, we obtain approximate self-energy corrections to the DFT highest occupied molecular orbital (HOMO) energy associated with BDA adsorbate phases. We find that, independent of coverage, the HOMO energy of the linear chain phase is lower relative to the Fermi energy than that of the monomer phase, and in good agreement with values measured with ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy.

  3. Challenges in the simulation of dye-sensitized ZnO solar cells: quantum confinement, alignment of energy levels and excited state nature at the dye/semiconductor interface.

    PubMed

    Amat, Anna; De Angelis, Filippo

    2012-08-14

    We report a first principles density functional theory/time-dependent density functional theory (DFT/TDDFT) computational investigation on a prototypical perylene dye anchored to realistic ZnO nanostructures, approaching the size of the ZnO nanowires used in dye-sensitized solar cells devices. DFT calculations were performed on (ZnO)(n) clusters of increasing size, with n up to 222, of 1.3 × 1.5 × 3.4 nm dimensions, and for the related dye-sensitized models. We show that quantum confinement in the ZnO nanostructures substantially affects the dye/semiconductor alignment of energy levels, with smaller ZnO models providing unfavourable electron injection. An increasing broadening of the dye LUMO is found moving to larger substrates, substantially contributing to the interfacial electronic coupling. TDDFT excited state calculations for the investigated dye@(ZnO)(222) system are fully consistent with experimental data, quantitatively reproducing the red-shift and broadening of the visible absorption spectrum observed for the ZnO-anchored dye compared to the dye in solution. TDDFT calculations on the fully interacting system also introduce a contribution to the dye/semiconductor admixture, due to configurational excited state mixing. Our results highlight the importance of quantum confinement in dye-sensitized ZnO interfaces, and provide the fundamental insight lying at the heart of the associated DSC devices. PMID:22743544

  4. A Dastardly Density Deed.

    ERIC Educational Resources Information Center

    Shaw, Mike

    2003-01-01

    Integrates story telling into a science activity on the density of liquids in order to increase student interest. Shows the relationship between mass and volume ratio and how they determine density. Includes teacher notes. (YDS)

  5. Direct Density Derivative Estimation.

    PubMed

    Sasaki, Hiroaki; Noh, Yung-Kyun; Niu, Gang; Sugiyama, Masashi

    2016-06-01

    Estimating the derivatives of probability density functions is an essential step in statistical data analysis. A naive approach to estimate the derivatives is to first perform density estimation and then compute its derivatives. However, this approach can be unreliable because a good density estimator does not necessarily mean a good density derivative estimator. To cope with this problem, in this letter, we propose a novel method that directly estimates density derivatives without going through density estimation. The proposed method provides computationally efficient estimation for the derivatives of any order on multidimensional data with a hyperparameter tuning method and achieves the optimal parametric convergence rate. We further discuss an extension of the proposed method by applying regularized multitask learning and a general framework for density derivative estimation based on Bregman divergences. Applications of the proposed method to nonparametric Kullback-Leibler divergence approximation and bandwidth matrix selection in kernel density estimation are also explored. PMID:27140943

  6. Density distributions in nuclei

    NASA Astrophysics Data System (ADS)

    Strutinsky, V. M.; Magner, A. G.; Denisov, V. Yu.

    1985-03-01

    Density distribution across the nuclear surface is obtained in the approximation of relatively sharp nuclear edge. It is used to determine dynamical parts of the density relevant to density vibration resonances. Results of the simple calculations are in close agreement with detailed microscopic theories.

  7. Crowding and Density

    ERIC Educational Resources Information Center

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  8. The Concept of Density

    ERIC Educational Resources Information Center

    Hawkes, Stephen J.

    2004-01-01

    Students are aware of the theoretical or abstract concept of density, but fail to understand its practical implication in that the thickness concentrated in a solid object is what constitutes density. A study of the density concept reveals its very practical and qualitative nature, and the students must look beyond theoretical equations to…

  9. Measurements of continuum lowering in solid-density plasmas created from elements and compounds.

    PubMed

    Ciricosta, O; Vinko, S M; Barbrel, B; Rackstraw, D S; Preston, T R; Burian, T; Chalupský, J; Cho, B I; Chung, H-K; Dakovski, G L; Engelhorn, K; Hájková, V; Heimann, P; Holmes, M; Juha, L; Krzywinski, J; Lee, R W; Toleikis, S; Turner, J J; Zastrau, U; Wark, J S

    2016-01-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations.

  10. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    PubMed Central

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H. -K.; Dakovski, G. L.; Engelhorn, K.; Hájková, V.; Heimann, P.; Holmes, M.; Juha, L.; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J. J.; Zastrau, U.; Wark, J. S.

    2016-01-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations. PMID:27210741

  11. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    NASA Astrophysics Data System (ADS)

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H.-K.; Dakovski, G. L.; Engelhorn, K.; Hájková, V.; Heimann, P.; Holmes, M.; Juha, L.; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J. J.; Zastrau, U.; Wark, J. S.

    2016-05-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations.

  12. Measurements of continuum lowering in solid-density plasmas created from elements and compounds.

    PubMed

    Ciricosta, O; Vinko, S M; Barbrel, B; Rackstraw, D S; Preston, T R; Burian, T; Chalupský, J; Cho, B I; Chung, H-K; Dakovski, G L; Engelhorn, K; Hájková, V; Heimann, P; Holmes, M; Juha, L; Krzywinski, J; Lee, R W; Toleikis, S; Turner, J J; Zastrau, U; Wark, J S

    2016-01-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations. PMID:27210741

  13. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    DOE PAGESBeta

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H. -K.; Dakovski, G. L.; et al

    2016-05-23

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. In this study, we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffectedmore » by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. Lastly, the results have implications for the standard approaches to the equation of state calculations.« less

  14. Intramolecular Nuclear Flux Densities

    NASA Astrophysics Data System (ADS)

    Barth, I.; Daniel, C.; Gindensperger, E.; Manz, J.; PéRez-Torres, J. F.; Schild, A.; Stemmle, C.; Sulzer, D.; Yang, Y.

    The topic of this survey article has seen a renaissance during the past couple of years. Here we present and extend the results for various phenomena which we have published from 2012-2014, with gratitude to our coauthors. The new phenomena include (a) the first reduced nuclear flux densities in vibrating diatomic molecules or ions which have been deduced from experimental pump-probe spectra; these "experimental" nuclear flux densities reveal several quantum effects including (b) the "quantum accordion", i.e., during the turn from bond stretch to bond compression, the diatomic system never stands still — instead, various parts of it with different bond lengths flow into opposite directions. (c) Wavepacket interferometry has been extended from nuclear densities to flux densities, again revealing new phenomena: For example, (d) a vibrating nuclear wave function with compact initial shape may split into two partial waves which run into opposite directions, thus causing interfering flux densities. (e) Tunneling in symmetric 1-dimensional double-well systems yields maximum values of the associated nuclear flux density just below the potential barrier; this is in marked contrast with negligible values of the nuclear density just below the barrier. (f) Nuclear flux densities of pseudorotating nuclei may induce huge magnetic fields. A common methodologic theme of all topics is the continuity equation which connects the time derivative of the nuclear density to the divergence of the flux density, subject to the proper boundary conditions. (g) Nearly identical nuclear densities with different boundary conditions may be related to entirely different flux densities, e.g., during tunneling in cyclic versus non-cyclic systems. The original continuity equation, density and flux density of all nuclei, or of all nuclear degrees of freedom, may be reduced to the corresponding quantities for just a single nucleus, or just a single degree of freedom.

  15. Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG.

    PubMed

    Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

    2016-01-21

    Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

  16. Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG

    NASA Astrophysics Data System (ADS)

    Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

    2016-01-01

    Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

  17. Energy level alignment of self-assembled linear chains of benzenediamine on Au(111) from first principles

    DOE PAGESBeta

    Li, Guo; Rangel, Tonatiuh; Liu, Zhen -Fei; Cooper, Valentino R.; Neaton, Jeffrey B.

    2016-03-24

    Using density functional theory (DFT) with van der Waals functionals, we calculate the adsorption energetics and geometry of benzenediamine (BDA) molecules on Au(111) surfaces. Our results demonstrate that the reported self-assembled linear chain structure of BDA, stabilized via hydrogen bonds between amine groups, is energetically favored over previously-studied monomeric phases. Moreover, using a model based on many-body perturbation theory within the GW approximation, we obtain approximate self-energy corrections to the DFT highest occupied molecular orbital (HOMO) energy associated with BDA adsorbate phases. As a result, we find that, independent of coverage, the HOMO energy of the linear chain phase ismore » lower relative to the Fermi energy than that of the monomer phase, and in good agreement with values measured with ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy.« less

  18. Identification of new fluorescence processes in the UV spectra of cool stars from new energy levels of Fe II and Cr II

    NASA Technical Reports Server (NTRS)

    Johansson, Sveneric; Carpenter, Kenneth G.

    1988-01-01

    Two fluorescence processes operating in atmospheres of cool stars, symbiotic stars, and the Sun are presented. Two emission lines, at 1347.03 and 1360.17 A, are identified as fluorescence lines of Cr II and Fe II. The lines are due to transitions from highly excited levels, which are populated radiatively by the hydrogen Lyman alpha line due to accidental wavelength coincidences. Three energy levels, one in Cr II and two in Fe II, are reported.

  19. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    PubMed

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells. PMID:26926667

  20. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    PubMed

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.

  1. Cu2ZnSnSe4 nanocrystals capped with S(2-) by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination.

    PubMed

    Wang, Xia; Kou, Dong-Xing; Zhou, Wen-Hui; Zhou, Zheng-Ji; Wu, Si-Xin; Cao, Xuan

    2014-01-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S(2-) decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed.

  2. Isolated energy level in the band gap of Yb2Si2O7 identified by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Ogawa, Takafumi; Kobayashi, Shunsuke; Wada, Masashi; Fisher, Craig A. J.; Kuwabara, Akihide; Kato, Takeharu; Yoshiya, Masato; Kitaoka, Satoshi; Moriwake, Hiroki

    2016-05-01

    We report the detection of an isolated energy level in the band gap of crystalline Yb2Si2O7 in the low-energy-loss region of its electron energy-loss (EEL) spectrum, obtained using a monochromated scanning transmission electron microscope. The experimental results are corroborated by first-principles calculations of the theoretical EEL spectrum. The calculations reveal that unoccupied Yb 4 f orbitals constitute an isolated energy level about 1 eV below the conduction band minimum (CBM), resulting in a terrace about 1 eV wide at the band edge of the EEL spectrum. In the case of Yb2O3 , no band edge terrace is present because the unoccupied f level lies just below the CBM. We also examined optical absorption properties of Yb2Si2O7 using UV-vis diffuse reflectance spectroscopy, which shows that the isolated energy level could not be detected in the band edge of the obtained absorbance spectrum. These findings demonstrate the utility of low-loss EEL spectroscopy with high energy resolution for probing semilocalized electronic features.

  3. Cu2ZnSnSe4 nanocrystals capped with S(2-) by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination.

    PubMed

    Wang, Xia; Kou, Dong-Xing; Zhou, Wen-Hui; Zhou, Zheng-Ji; Wu, Si-Xin; Cao, Xuan

    2014-01-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S(2-) decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed. PMID:24994951

  4. Cu2ZnSnSe4 nanocrystals capped with S2− by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination

    PubMed Central

    2014-01-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S2− decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed. PMID:24994951

  5. Average density in cosmology

    SciTech Connect

    Bonnor, W.B.

    1987-05-01

    The Einstein-Straus (1945) vacuole is here used to represent a bound cluster of galaxies embedded in a standard pressure-free cosmological model, and the average density of the cluster is compared with the density of the surrounding cosmic fluid. The two are nearly but not quite equal, and the more condensed the cluster, the greater the difference. A theoretical consequence of the discrepancy between the two densities is discussed. 25 references.

  6. Visualization of electronic density

    DOE PAGESBeta

    Grosso, Bastien; Cooper, Valentino R.; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan

    2015-04-22

    An atom’s volume depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent numerical algorithms and packages to calculate it for other materials. 3D visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. We explore several approaches to 3D charge density visualization, including the extension of an anaglyphic stereo visualization application based on the AViz package to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting questions about nanotube properties.

  7. Martian drainage densities

    USGS Publications Warehouse

    Carr, M.H.; Chuang, F.C.

    1997-01-01

    Drainage densities on Mars range from zero over large areas of volcanic plains to 0.3-0.5 km-1 locally on some volcanoes. These values refer to geologic units, not to drainage basins, as is normal for terrestrial drainage densities. The highest values are close to the lowest terrestrial values derived by similar techniques. Drainage densities were determined for every geologic unit portrayed on the 1:15,000,000 geologic map of Mars. Except for volcanoes the geologic unit with the highest drainage density is the dissected Noachian plains with a drainage density of 0.0074 km-1. The average drainage density for Noachian units is 0.0032 km-1, for Hesperian units is 0.00047 km-1, and for Amazonian units is 0.00007 km-1, excluding the volcanoes. These values are 2-3 orders of magnitude lower than typical terrestrial densities as determined by similar techniques from Landsat images. The low drainage densities, despite a cumulative record that spans billions of years, indicate that compared with the Earth, the channel-forming processes have been very inefficient or have operated only rarely or that the surface is extremely permeable. The high drainage density on volcanoes is attributed to a local cause, such as hydrothermal activity, rather than to a global cause such as climate change. Copyright. Published in 1997 by the American Geophysical Union.

  8. Effect of precalving and postcalving dietary energy level on performance and blood metabolite concentrations of dairy cows throughout lactation.

    PubMed

    Law, R A; Young, F J; Patterson, D C; Kilpatrick, D J; Wylie, A R G; Ingvarsten, K L; Hameleers, A; McCoy, M A; Mayne, C S; Ferris, C

    2011-02-01

    The effects of the level of energy intake (high E and low E) offered before and after calving on body condition score at calving, production performance, and energy status in the first 250 d of lactation were evaluated in a 2 × 2 factorial design experiment involving 80 Holstein-Friesian dairy animals (40 primiparous and 40 multiparous). From d 80 until d 21 precalving, primiparous animals were offered either high or low pasture allowances. Thereafter, these animals were housed and had ad libitum access to a high energy density diet (high E) or restricted access [6 kg of dry matter (DM) per d] to a low energy density diet (low E), respectively, until calving. From d 100 until d 42 precalving, multiparous animals were offered either ad libitum or restricted (10 kg of DM/d) access to a late lactation diet, and thereafter, had ad libitum access to a high E diet or restricted access (7 kg of DM complete diet/d) to a low E diet, respectively, until calving. The forage to concentrate (F:C) ratios (DM basis) of these high E and low E diets [d 42 (d 21 in primiparous animals) until calving] were 64:36 and 83:17, respectively. Cows offered high E and low E precalving diets were allocated to either a high E or low E postcalving diet [F:C ratio (DM basis) of 30:70 and 70:30, respectively] and remained on these diets until d 250 of lactation. Multiparous animals offered a high E diet precalving had a significantly higher body condition score at calving than those offered the low E diet precalving. This effect was not evident in primiparous animals. Precalving diet had no significant effect on plasma nonesterified fatty acid concentrations during the last 3 wk precalving in primi- or multiparous animals. Primiparous animals offered a high E diet precalving had significantly higher postcalving plasma concentrations of nonesterified fatty acid, suggesting greater mobilization of body reserves. Primi- and multiparous animals offered a high E diet postcalving had a significantly

  9. CRDS of 17O enriched water between 5850 and 6671 cm-1: More than 1000 energy levels of H217O and HD17O newly determined

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Leshchishina, O.; Karlovets, E. V.; Mondelain, D.; Kassi, S.; Campargue, A.

    2016-07-01

    The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 5850 and 6671 cm-1. Two series of recordings were performed with pressure values of 1.0 and 12.0 Torr. The investigated spectral region corresponds to the important 1.55 μm transparency window of the atmosphere where water absorption is very weak. The high sensitivity of the recordings (αmin ~ 5×10-11 cm-1) allows detecting lines with intensity spanning six orders of magnitude (1.4×10-30-3.6×10-24 cm/molecule at room temperature). The experimental list includes more than 10,300 lines. The assignments of water lines were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. More than 8500 lines were assigned to 9619 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). All but four transitions of the 16O and 18O isotopologues were assigned using known experimental energy levels. More than half of the assigned H217O and HD17O transitions correspond to new (or corrected) upper energy levels. About 1000 new H217O transitions associated with upper states of the second triad and of the first hexad were identified. Most of the newly assigned HD17O transitions belong to the ν1+ν3 and 2ν2+ν3 bands. The assigned transitions allowed to newly determine or correct 20 highly excited rotational levels of the vibrational ground state of this isotopologue. Overall 791 and 266 energy levels are newly determined for H217O and HD17O, respectively. A few additional levels were corrected compared to literature values. The obtained experimental results are compared to the spectroscopic parameters provided by the HITRAN database and to the empirical energy levels recommended by an IUPAC task group.

  10. CRDS of 17O enriched water between 5850 and 6671 cm-1: More than 1000 energy levels of H217O and HD17O newly determined

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Leshchishina, O.; Karlovets, E. V.; Mondelain, D.; Kassi, S.; Campargue, A.

    2016-07-01

    The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 5850 and 6671 cm-1. Two series of recordings were performed with pressure values of 1.0 and 12.0 Torr. The investigated spectral region corresponds to the important 1.55 μm transparency window of the atmosphere where water absorption is very weak. The high sensitivity of the recordings (αmin ~ 5×10-11 cm-1) allows detecting lines with intensity spanning six orders of magnitude (1.4×10-30-3.6×10-24 cm/molecule at room temperature). The experimental list includes more than 10,300 lines. The assignments of water lines were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. More than 8500 lines were assigned to 9619 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). All but four transitions of the 16O and 18O isotopologues were assigned using known experimental energy levels. More than half of the assigned H217O and HD17O transitions correspond to new (or corrected) upper energy levels. About 1000 new H217O transitions associated with upper states of the second triad and of the first hexad were identified. Most of the newly assigned HD17O transitions belong to the ν1+ν3 and 2ν2+ν3 bands. The assigned transitions allowed to newly determine or correct 20 highly excited rotational levels of the vibrational ground state of this isotopologue. Overall 791 and 266 energy levels are newly determined for H217O and HD17O, respectively. A few additional levels were corrected compared to literature values. The obtained experimental results are compared to the spectroscopic parameters provided by the HITRAN database and to the empirical energy levels recommended by an IUPAC task group.

  11. Density-dependent covariant energy density functionals

    SciTech Connect

    Lalazissis, G. A.

    2012-10-20

    Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

  12. Density in a Bottle.

    ERIC Educational Resources Information Center

    Roser, Charles E.; McCluskey, Catherine L.

    1998-01-01

    Explains how the Canadian soft drink Orbitz can be used for explorations of density in the classroom. The drink has colored spheres suspended throughout that have a density close to that of the liquid. Presents a hands-on activity that can be easily done in two parts. (DDR)

  13. Variable Density Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Variable Density Tunnel in operation. Man at far right is probably Harold J. 'Cannonball' Tuner, longtime safety officer, who started with Curtiss in the teens. This view of the Variable Density Tunnel clearly shows the layout of the Tunnel's surroundings, as well as the plumbing and power needs of the this innovative research tool.

  14. 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.

  15. PdO doping tunes band-gap energy levels as well as oxidative stress responses to a Co₃O₄ p-type semiconductor in cells and the lung.

    PubMed

    Zhang, Haiyuan; Pokhrel, Suman; Ji, Zhaoxia; Meng, Huan; Wang, Xiang; Lin, Sijie; Chang, Chong Hyun; Li, Linjiang; Li, Ruibin; Sun, Bingbing; Wang, Meiying; Liao, Yu-Pei; Liu, Rong; Xia, Tian; Mädler, Lutz; Nel, André E

    2014-04-30

    We demonstrate through PdO doping that creation of heterojunctions on Co3O4 nanoparticles can quantitatively adjust band-gap and Fermi energy levels to study the impact of metal oxide nanoparticle semiconductor properties on cellular redox homeostasis and hazard potential. Flame spray pyrolysis (FSP) was used to synthesize a nanoparticle library in which the gradual increase in the PdO content (0-8.9%) allowed electron transfer from Co3O4 to PdO to align Fermi energy levels across the heterojunctions. This alignment was accompanied by free hole accumulation at the Co3O4 interface and production of hydroxyl radicals. Interestingly, there was no concomitant superoxide generation, which could reflect the hole dominance of a p-type semiconductor. Although the electron flux across the heterojunctions induced upward band bending, the E(c) levels of the doped particles showed energy overlap with the biological redox potential (BRP). This allows electron capture from the redox couples that maintain the BRP from -4.12 to -4.84 eV, causing disruption of cellular redox homeostasis and induction of oxidative stress. PdO/Co3O4 nanoparticles showed significant increases in cytotoxicity at 25, 50, 100, and 200 μg/mL, which was enhanced incrementally by PdO doping in BEAS-2B and RAW 264.7 cells. Oxidative stress presented as a tiered cellular response involving superoxide generation, glutathione depletion, cytokine production, and cytotoxicity in epithelial and macrophage cell lines. A progressive series of acute pro-inflammatory effects could also be seen in the lungs of animals exposed to incremental PdO-doped particles. All considered, generation of a combinatorial PdO/Co3O4 nanoparticle library with incremental heterojunction density allowed us to demonstrate the integrated role of E(v), E(c), and E(f) levels in the generation of oxidant injury and inflammation by the p-type semiconductor, Co3O4. PMID:24673286

  16. PdO Doping Tunes Band-Gap Energy Levels as Well as Oxidative Stress Responses to a Co3O4p-Type Semiconductor in Cells and the Lung

    PubMed Central

    2014-01-01

    We demonstrate through PdO doping that creation of heterojunctions on Co3O4 nanoparticles can quantitatively adjust band-gap and Fermi energy levels to study the impact of metal oxide nanoparticle semiconductor properties on cellular redox homeostasis and hazard potential. Flame spray pyrolysis (FSP) was used to synthesize a nanoparticle library in which the gradual increase in the PdO content (0–8.9%) allowed electron transfer from Co3O4 to PdO to align Fermi energy levels across the heterojunctions. This alignment was accompanied by free hole accumulation at the Co3O4 interface and production of hydroxyl radicals. Interestingly, there was no concomitant superoxide generation, which could reflect the hole dominance of a p-type semiconductor. Although the electron flux across the heterojunctions induced upward band bending, the Ec levels of the doped particles showed energy overlap with the biological redox potential (BRP). This allows electron capture from the redox couples that maintain the BRP from −4.12 to −4.84 eV, causing disruption of cellular redox homeostasis and induction of oxidative stress. PdO/Co3O4 nanoparticles showed significant increases in cytotoxicity at 25, 50, 100, and 200 μg/mL, which was enhanced incrementally by PdO doping in BEAS-2B and RAW 264.7 cells. Oxidative stress presented as a tiered cellular response involving superoxide generation, glutathione depletion, cytokine production, and cytotoxicity in epithelial and macrophage cell lines. A progressive series of acute pro-inflammatory effects could also be seen in the lungs of animals exposed to incremental PdO-doped particles. All considered, generation of a combinatorial PdO/Co3O4 nanoparticle library with incremental heterojunction density allowed us to demonstrate the integrated role of Ev, Ec, and Ef levels in the generation of oxidant injury and inflammation by the p-type semiconductor, Co3O4. PMID:24673286

  17. Effects of valence-valence, core-valence and core-core correlations on the fine-structure energy levels in Zn-like ions

    NASA Astrophysics Data System (ADS)

    Hu, F.; Jiang, G.; Yang, J. M.; Wang, C. K.; Zhao, X. F.; Hao, L. H.

    2011-01-01

    We report on large ab initio calculation for the 4s^2- 4s4p transitions in the Zinc-like sequence, using the multi-configuration Dirac-Hartree-Fock method. Results for fine-structure energy levels, the wavelengths, transition rates and lifetimes between Z = 70 (Yb) and Z= 92 (U) are presented and compared with other theories and experiments. The calculated values including core-valence correlation are found to be similar and to compare very well with other theories and experiments values. We believe that our extensive calculated values can guide experimentalists in identifying the fine-structure levels in their future work.

  18. Energy levels and radiative rates for transitions in B-like to F-like Kr ions (Kr XXXII-XXVIII)

    SciTech Connect

    Aggarwal, K.M. Keenan, F.P.; Lawson, K.D.

    2008-05-15

    Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Kr ions, Kr XXXIII-XXVIII. For the calculations, the fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 125, 236, 272, 226, and 113 levels of Kr XXXII, Kr XXXI, Kr XXX, Kr XXIX, and Kr XXVIII, respectively, belonging to the n {<=} 3 configurations. Comparisons are made with earlier available theoretical and experimental results, and some discrepancies have been noted and explained.

  19. Energy levels and radiative rates for transitions in B-like to F-like Xe ions (Xe L-XLVI)

    SciTech Connect

    Aggarwal, K.M. Keenan, F.P.; Lawson, K.D.

    2010-03-15

    Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Xe ions, Xe L-XLVI. For the calculations, a fully relativistic GRASP code has been adopted, and results are reported for all electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole transitions among the lowest 125, 236, 272, 226, and 113 levels of Xe L, Xe XLIX, Xe XLVIII, Xe XLVII, and Xe XLVI, respectively, belonging to the n {<=} 3 configurations.

  20. Tuning the energy level offset between donor and acceptor with ferroelectric dipole layers for increased efficiency in bilayer organic photovoltaic cells.

    PubMed

    Yang, Bin; Yuan, Yongbo; Sharma, Pankaj; Poddar, Shashi; Korlacki, Rafal; Ducharme, Stephen; Gruverman, Alexei; Saraf, Ravi; Huang, Jinsong

    2012-03-15

    Ultrathin ferroelectric polyvinylidene fluoride (70%)-tetrafluoroethylene (30%) copolymer film is inserted between the poly3(hexylthiophene) (P3HT) donor and [6,6]-phenyl-C61-butyric acid methylester (PCBM) acceptor layers as the dipole layer to tune the relative energy levels, which can potentially maximize the open circuit voltage of bilayer organic solar cells. In this work, the power conversion efficiency of P3HT/PCBM bilayer solar cells is demonstrated to be doubled with the inserted dipoles. PMID:22328442

  1. Critical Density Interaction Studies

    SciTech Connect

    Young, P; Baldis, H A; Cheung, P; Rozmus, W; Kruer, W; Wilks, S; Crowley, S; Mori, W; Hansen, C

    2001-02-14

    Experiments have been performed to study the propagation of intense laser pulses to high plasma densities. The issue of self-focusing and filamentation of the laser pulse as well as developing predictive capability of absorption processes and x-ray conversion efficiencies is important for numerous programs at the Laboratory, particularly Laser Program (Fast Ignitor and direct-drive ICF) and D&NT (radiography, high energy backlighters and laser cutting). Processes such as resonance absorption, profile modification, linear mode conversion, filamentation and stimulated Brillouin scattering can occur near the critical density and can have important effects on the coupling of laser light to solid targets. A combination of experiments have been used to study the propagation of laser light to high plasma densities and the interaction physics of intense laser pulses with solid targets. Nonparaxial fluid codes to study nonstationary behavior of filamentation and stimulated Brillouin scattering at high densities have also been developed as part of this project.

  2. Genetics of Bone Density

    MedlinePlus

    ... study linked 32 novel genetic regions to bone mineral density. The findings may help researchers understand why ... or treating osteoporosis. Bones are made of a mineral and protein scaffold filled with bone cells. Bone ...

  3. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    Wind Tunnel #2, building interior. Reinforced concrete foundation for Variable-Density Tunnel (VDT) under construction. The tank and contents weighed about 100 tons. Negative on roll #1 of copy negatives returned by National Archives on 70mm film rolls.

  4. Density on Dry Land.

    ERIC Educational Resources Information Center

    Libarkin, Julie C.; Crockett, Cynthia D.; Sadler, Philip M.

    2003-01-01

    Presents activities to dispel student misconceptions about density, particularly as it applies to buoyancy. Finds that misconceptions fall under three categories: (1) size; (2) shape; and (3) material. (NB)

  5. Nutrient Density Scores.

    ERIC Educational Resources Information Center

    Dickinson, Annette; Thompson, William T.

    1979-01-01

    Announces a nutrient density food scoring system called the Index of Nutritional Quality (INQ). It expresses the ratio between the percent RDA of a nutrient and the percent daily allowance of calories in a food. (Author/SA)

  6. The local mass density

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.

    1974-01-01

    An improved mass-luminosity relation for faint main-sequence stars derived from recently revised masses for some faint double stars is presented. The total local mass density is increased to nearly 0.2 solar masses per cu pc. This estimate is as large as the mass density required by Oort's (1965) dynamical analysis of stellar motions perpendicular to the galactic plane if the mass is concentrated in a narrow layer.

  7. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  8. Energy levels, radiative rates, and electron impact excitation rates for transitions in Li-like ions with 12≤Z≤20

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2013-03-15

    We report calculations of energy levels, radiative rates, and electron impact excitation rates for transitions in Li-like ions with 12≤Z≤20. The GRASP (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates, while for determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code is used. Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest 24 levels of the Li-like ions considered. Collision strengths have been averaged over a Maxwellian velocity distribution, and the effective collision strengths obtained are reported over a wide temperature range up to 10{sup 7.4} K. Additionally, lifetimes are also listed for all calculated levels of the ions. Finally, extensive comparisons are made with results available in the literature, as well as with our parallel calculations for all parameters with the Flexible Atomic Code, in order to assess the accuracy of the reported results.

  9. Improved low-lying energy levels determined from solar coronal forbidden and spin-forbidden lines in the 500-1500 A range

    SciTech Connect

    Feldman, U.; Doschek, G.A. . E-mail: george.doschek@nrl.navy.mil

    2007-09-15

    We list observed parity-forbidden and spin-forbidden lines in the 500-1600 A range emitted by solar coronal plasmas and derive improved energy levels from their wavelengths. The lines, emitted by astrophysical abundant elements, belong to transitions within the ground configurations of the type ns{sup 2} np {sup k}, for n = 2, 3 and k = 0-5, and between the lowest term of the first excited configuration 2s2p {sup k+1} and the 2s{sup 2}2p {sup k} ground configurations for k = 0, 1, 2. For each line we give the newly measured wavelength, and the measured or predicted wavelength from the NIST Atomic Spectra Database (ASD) (which except for a few cases includes the previously reported compilation of Kaufman and Sugar [J. Phys. Chem. Ref. Data 15 (1986) 321]), and the values of the transition probability taken from the ASD and CHIANTI database. The list contains measured wavelengths of 136 lines of which over 100 were not available for the Kaufman and Sugar compilation. In addition we provide energy levels that were derived from the reported lines.

  10. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis.

    PubMed

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-26

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum. PMID:27420635

  11. Calculation of Rotation-Vibration Energy Levels of the Water Molecule with Near-Experimental Accuracy Based on an ab Initio Potential Energy Surface

    NASA Astrophysics Data System (ADS)

    Polyansky, Oleg L.; Ovsyannikov, Roman I.; Kyuberis, Aleksandra A.; Lodi, Lorenzo; Tennyson, Jonathan; Zobov, Nikolai F.

    2013-10-01

    A recently computed, high-accuracy ab initio Born-Oppenheimer (BO) potential energy surface (PES) for the water molecule is combined with relativistic, adiabatic, quantum electrodynamics, and, crucially, nonadiabatic corrections. Calculations of ro-vibrational levels are presented for several water isotopologues and shown to have unprecedented accuracy. A purely ab initio calculation reproduces some 200 known band origins associated with seven isotopologues of water with a standard deviation (σ) of about 0.35 cm-1. Introducing three semiempirical scaling parameters, two affecting the BO PES and one controlling nonadiabatic effects, reduces σ below 0.1 cm-1. Introducing one further rotational nonadiabatic parameter gives σ better than 0.1 cm-1 for all observed ro-vibrational energy levels up to J = 25. We conjecture that the energy levels of closed-shell molecules with roughly the same number of electrons as water, such as NH3, CH4, and H3O+, could be calculated to this accuracy using an analogous procedure. This means that near-ab initio calculations are capable of predicting transition frequencies with an accuracy only about a factor of 5 worse than high resolution experiments.

  12. Energy levels, oscillator strengths and transition probabilities for Si-like P II, S III, Cl IV, Ar V and K VI

    SciTech Connect

    Abou El-Maaref, A.; Uosif, M.A.M.; Allam, S.H.; El-Sherbini, Th.M.

    2012-07-15

    Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for transitions among the terms belonging to 3s{sup 2}3p{sup 2}, 3s3p{sup 3}, 3s{sup 2}3p3d, 3s{sup 2}3p4s, 3s{sup 2}3p4p, 3s{sup 2}3p4d, 3s{sup 2}3p5s and 3s{sup 2}3p5p configurations of silicon-like ions P II, S III, Cl IV, Ar V and K VI have been calculated using configuration-interaction version 3 (CIV3). We compared our data with the available experimental data and other theoretical calculations. Most of our calculations of energy levels and oscillator strengths (in length form) show good agreement with both experimental and theoretical data. Lifetimes of the excited levels are also given.

  13. Effects of feeding different dietary protein and energy levels on the performance of 12-15-month-old buffalo calves.

    PubMed

    Shahzad, Muhammad Aasif; Tauqir, Nasir A; Ahmad, Fayyaz; Nisa, Mahr U; Sarwar, Muhammad; Tipu, Murtaza A; Tipu, Muhammad A

    2011-03-01

    The study investigated the performance response of different dietary protein and energy levels of Nili-Ravi buffalo calves. Sixty buffalo calves of 12-15 months of age and similar body weight (140 ± 14 kg) were divided in to 12 groups, five animals in each group, according to 4 × 3 factorial arrangements. Twelve rations were formulated containing four levels of crude protein (CP; 10.5%, 12.20%, 13.80%, and 15.55%) each with three levels (1.72, 2.11, and 2.5 Mcal/Kg) of metabolizable energy (ME). Experiment lasted for 100 days; first 10 days were given for dietary adaptation. Daily feed consumption in calves fed all experimental diets were statistically significant (p<0.05) across all treatments. Higher feed intake was observed in buffalo calves fed diets containing 12.20% and 13.85% CP with 2.11 Mcal/kg ME. Results of dry matter (DM) digestion were significantly different (p<0.05) across all treatments. There was a quadratic (p<0.05) response of DM digestibility for levels of dietary protein while, curvilinear (p<0.05) trend with respect to dietary energy levels. Daily weight gain of buffalo calves did not show any treatment effect. The outcome of the present study indicate that 12-15-month-old buffalo calves perform adequately well when fed on diets containing 12.2% CP and 2.10 ME Mcal/Kg. PMID:21107907

  14. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-01

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  15. Photoluminescence properties and energy levels of RE (RE = Pr, Sm, Er, Tm) in layered-CaZnOS oxysulfide

    SciTech Connect

    Zhang, Zhi-Jun; Feng, Ang; Chen, Xiang-Yang; Zhao, Jing-Tai

    2013-12-07

    RE{sup 3+} (RE = Pr, Sm, Er, Tm)-activated CaZnOS samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. Doping with RE{sup 3+} (RE = Pr, Sm, Er, Tm) into layered-CaZnOS resulted in typical RE{sup 3+} (RE = Pr, Sm, Er, Tm) f-f line absorptions and emissions, as well as the charge transfer band of Sm{sup 3+} at about 3.3 eV. The energy level scheme containing the position of the 4f and 5d levels of all divalent and trivalent lanthanide ions with respect to the valence and conduction bands of CaZnOS has been constructed based on the new data presented in this work, together with the data from literature on Ce{sup 3+} and Eu{sup 2+} doping in CaZnOS. The detailed energy level scheme provides a platform for interpreting the optical spectra and could be used to comment on the valence stability of the lanthanide ions in CaZnOS.

  16. Modelling ionospheric density structures

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Sojka, J. J.

    1989-01-01

    Large-scale density structures are a common feature in the high-latitude ionsphere. The structures were observed in the dayside cusp, polar cap, and nocturnal auroral region over a range of altitudes, including the E-region, F-region and topside ionosphere. The origins, lifetimes and transport characteristics of large-scale density structures were studied with the aid of a three-dimensional, time-dependent ionospheric model. Blob creation due to particle precipitation, the effect that structured electric fields have on the ionosphere, and the lifetimes and transport characteristics of density structures for different seasonal, solar cycle, and interplanetary magnetic field (IMF) conditions were studied. The main conclusions drawn are: (1) the observed precipitation energy fluxes are sufficient for blob creation if the plasma is exposed to the precipitation for 5 to 10 minutes; (2) structured electric fields produce structured electron densities, ion temperatures, and ion composition; (3) the lifetime of an F-region density structure depends on several factors, including the initial location where it was formed, the magnitude of the perturbation, season, solar cycle and IMF; and (4) depending on the IMF, horizontal plasma convection can cause an initial structure to break up into multiple structures of various sizes, remain as a single distorted structure, or become stretched into elongated segments.

  17. Density variations in thermoelectrics

    SciTech Connect

    Mahan, G. D.

    2000-05-15

    Equations are solved to give the variations in temperature, density, and potential, when a solid has electrical currents, heat currents, and particle diffusion. Solutions are presented in one dimension for currents down a bar. These solutions are used to calculate the efficiency of a thermoelectric refrigerator, which is optimized to give the coefficient of performance (COP). The COP depends upon the temperature difference {delta}T, but does not depend upon the density difference {delta}n between the two ends of the bar. (c) 2000 American Institute of Physics.

  18. Density Equalizing Map Projections

    1995-07-01

    A geographic map is mathematically transformed so that the subareas of the map are proportional to a given quantity such as population. In other words, population density is equalized over the entire map. The transformed map can be used as a display tool, or it can be statistically analyzed. For example, cases of disease plotted on the transformed map should be uniformly distributed at random, if disease rates are everywhere equal. Geographic clusters of diseasemore » can be readily identified, and their statistical significance determined, on a density equalized map.« less

  19. Energy level structure of 4f5d states and the Stokes shift in LaPO4:Pr3+ : A theoretical study

    NASA Astrophysics Data System (ADS)

    Bagatur'Yants, A. A.; Iskandarova, I. M.; Knizhnik, A. A.; Mironov, V. S.; Potapkin, B. V.; Srivastava, A. M.; Sommerer, T. J.

    2008-10-01

    The energy levels and the Stokes shift of the excited 4f15d1 states of Pr3+ ions doped into LaPO4 are calculated using a combined theoretical approach. The local structure of the rare-earth site in LaPO4 is obtained from first-principles calculations, while the 4f15d1 states of Pr3+ are treated parametrically in terms of a model Hamiltonian. The crystal-field energies of the 5d electron of a low-symmetry rare-earth site in LaPO4 are obtained from angular-overlap model calculations. First-principles calculations are performed for LaPO4:Ce3+ used as a reference compound for LaPO4:Pr3+ ; the geometry parameters of the rare-earth site are determined for the ground state (4f) and for the excited (5d) state of the central Ce3+ ion. It is shown that the 4f-5d excitation in LaPO4:Ce3+ is accompanied by a strong relaxation of the local structure of the rare-earth site due to rotations of one of the neighboring tetrahedral PO4 phosphate groups: the coordination number of Ce3+ reduces from nine to eight and the average Ce-O distance shortens by about 0.1Å . This leads to a considerably larger crystal-field splitting energy of the 5d states for the excited-state geometry of the cerium site ( ˜17700cm-1 vs ˜12000cm-1 in the ground state) and to a large 5d-4f Stokes shift in LaPO4:Ce3+ ( 3980cm-1 calculated and 4880cm-1 experimental). The 5d crystal-field splitting energies obtained for Ce3+ are then employed for calculations of the 4f15d1 energy levels in LaPO4:Pr3+ . The calculated Stokes shift in LaPO4:Pr3+ is 3610cm-1 . Due to such a large Stokes shift, in an excited Pr3+ ion the lowest 4f15d1 energy level lies below the upper S10(4f2) level, while in an unexcited ion (in the ground 4f2 state) the order of these states is reverse. This fact is responsible for the absence of 4f-4f emission from the S10 state in LaPO4:Pr3+ .

  20. Material and Optical Densities

    ERIC Educational Resources Information Center

    Gluck, Paul

    2007-01-01

    The bending of a laser beam in a medium with a density and refractive index gradient in the same direction has been described previously. When a transparent container is half filled with a salt or sugar solution and an equal amount of water is floated on top of it, then diffusion will create a concentration gradient from top to bottom. A laser…

  1. Density in Liquids.

    ERIC Educational Resources Information Center

    Nesin, Gert; Barrow, Lloyd H.

    1984-01-01

    Describes a fourth-grade unit on density which introduces a concept useful in the study of chemistry and procedures appropriate to the chemistry laboratory. The hands-on activities, which use simple equipment and household substances, are at the level of thinking Piaget describes as concrete operational. (BC)

  2. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  3. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  4. Incident meteoroid flux density

    NASA Technical Reports Server (NTRS)

    Badadjanov, P. B.; Bibarsov, R. SH.; Getman, V. S.; Kolmakov, V. M.

    1987-01-01

    Complex photographic and radar meteor observations were carried out. Using the available observational data, the density of incident flux of meteoroids was estimated over a wide mass range of 0.001 to 100 g. To avoid the influence of apparatus selectivity a special technique was applied. The main characteristics of this technique are given and discussed.

  5. Energy in density gradient

    SciTech Connect

    Vranjes, J.; Kono, M.

    2015-01-15

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  6. Culture systems: embryo density.

    PubMed

    Reed, Michael L

    2012-01-01

    Embryo density is defined as the embryo-to-volume ratio achieved during in vitro culture; in other words, it is the number of embryos in a defined volume of culture medium. The same density can be achieved by manipulating either the number of embryos in a given volume of medium, or manipulating the volume of the medium for a given number of embryos: for example, a microdrop with five embryos in a 50 μl volume under oil has the same embryo-to-volume ratio (1:10 μl) as a microdrop with one embryo in a 10 μl volume under oil (1:10 μl). Increased embryo density can improve mammalian embryo development in vitro; however, the mechanism(s) responsible for this effect may be different with respect to which method is used to increase embryo density.Standard, flat sterile plastic petri dishes are the most common, traditional platform for embryo culture. Microdrops under a mineral oil overlay can be prepared to control embryo density, but it is critical that dish preparation is consistent, where appropriate techniques are applied to prevent microdrop dehydration during preparation, and results of any data collection are reliable, and repeatable. There are newer dishes available from several manufacturers that are specifically designed for embryo culture; most are readily available for use with human embryos. The concept behind these newer dishes relies on fabrication of conical and smaller volume wells into the dish design, so that embryos rest at the lowest point in the wells, and where putative embryotrophic factors may concentrate.Embryo density is not usually considered by the embryologist as a technique in and of itself; rather, the decision to culture embryos in groups or individually is protocol-driven, and is based more on convenience or the need to collect data on individual embryos. Embryo density can be controlled, and as such, it can be utilized as a simple, yet effective tool to improve in vitro development of human embryos. PMID:22829380

  7. Partition density functional theory

    NASA Astrophysics Data System (ADS)

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  8. Electron capture and positron decay of /sup 206/Fr and /sup 208/Fr and the energy levels of /sup 206/Rn and /sup 208/Rn

    SciTech Connect

    Ritchie, B.G.; Avignone, F.T. III; Carter, H.K.; Mlekodaj, R.L.; Spejewski, E.H.

    1981-04-01

    The isotopes /sup 206/Fr and /sup 208/Fr were produced by the reactions Ir(/sup 20/Ne,xn)/sup 206,208/Fr and mass separated on-line. The electron-capture and positron decays to /sup 206/Rn and /sup 208/Rn were studied by collecting ..gamma.. ray and internal conversion electron singles spectra as a function of decay time as well as ..gamma..-..gamma.., ..gamma..-e/sup -/, and ..gamma..-x ray coincidence spectra. The energies and many of the spins were determined for 18 excited, even parity states in /sup 208/Rn and for 10 excited, even parity states in /sup 206/Rn. These nuclei appear to be excellent candidates for interpretation in terms of a weak coupling shell model. The energy levels were also compared to the predictions of the interacting boson approximation model.

  9. Effect of CSN1S1 genotype and its interaction with diet energy level on milk production and quality in Girgentana goats fed ad libitum.

    PubMed

    Pagano, Renato Italo; Pennisi, Pietro; Valenti, Bernardo; Lanza, Massimiliano; Di Trana, Adriana; Di Gregorio, Paola; De Angelis, Anna; Avondo, Marcella

    2010-05-01

    A study was carried out to evaluate how the energy level of the diet can affect milk production and quality in Girgentana lactating goats in relation to polymorphism at the alphas1-casein (CSN1S1) genotype locus. Twenty-seven goats, homogeneous for milk production (1.5+/-0.3 kg/d), days of lactation (90+/-10 d) and body weight (35.8+/-5.5 kg) were selected on the basis of their CSN1S1 genotype, as follows: nine goats homozygous for strong (AA) alleles, nine goats homozygous for weak alleles (FF) and nine goats heterozygous (AF). The goats were used in a 3x3 factorial arrangement of treatments, with three genotypes (AA, FF, AF) and three diets at different energy levels (100%, 65% and 30% of hay inclusion). The experiment consisted of three simultaneous 3x3 Latin squares for the three genotypes, with one square for each level of hay inclusion in the diet. All the animals were housed in individual pens. Each experimental period lasted 23 d and consisted of 15 d for adaptation and 8 d for data and sample collection, during which the goats received the scheduled diet ad libitum. The animals were fed three different diets designed to have the same crude protein content (about 15%) but different energy levels: a pelleted alfalfa hay (H100) and two feeds including 65% (H65) and 30% (H30) of alfalfa hay (respectively 1099, 1386 and 1590 kcal NE for lactation/kg DM). All the diets were ground and pelleted (6 mm diameter). AA goats were more productive than AF and FF goats (respectively: 1419 v. 1145 and 1014 g/d; P=0.002). Indeed the interaction energy levelxgenotype was significant (P=0.018): in fact AA goats showed their milk increase only when fed with concentrates. Differences in protein and in casein levels between the three genotypes were in line with results expected from the different allele contribution to alphas1-casein synthesis. Milk urea levels were significantly lower in AA goats compared with AF and FF genotypes (respectively 32.7 v. 40.4 and 40.4 mg/dl; P=0

  10. Theoretical studies of the crystal-field energy levels and EPR g factors for CeFeAsO1-xFx

    NASA Astrophysics Data System (ADS)

    Dong, Hui-Ning; Zhou, Hong-Fei; Yang, Guo-Ren

    2015-08-01

    The ion-based superconductor CeFeAsO1-xFx has received much attention because this rare earth oxypnictide belongs to a new class RFeAsO1-xFx of high-Tc superconductors with critical temperatures surpassed by high-Tc copper oxides. Since the Ce3+ is situated near the superconducting FeAs plane, it can be used as a probe to study the influence of superconductivity on spin dynamic properties of the FeAs layer. It is important to determine the optical and magnetic properties of rare earth ion in oxypnictides. Here, based on the crystal-field theory, the crystal-field (CF) energy levels and electron paramagnetic resonance parameters g factors of Ce3+ in CeFeAsO1-xFx are studied by diagonalizing the full energy matrix. In the calculations, the contributions of various admixtures and interactions are all considered. The results are discussed.

  11. Refinement of the experimental energy levels of higher {sup 2}D Rydberg states of the lithium atom with very accurate quantum mechanical calculations

    SciTech Connect

    Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, Ludwik

    2011-05-21

    Very accurate variational non-relativistic calculations are performed for four higher Rydberg {sup 2}D states (1s{sup 2}nd{sup 1}, n= 8, ..., 11) of the lithium atom ({sup 7}Li). The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions and finite nuclear mass is used. The exponential parameters of the Gaussians are optimized using the variational method with the aid of the analytical energy gradient determined with respect to those parameters. The results of the calculations allow for refining the experimental energy levels determined with respect to the {sup 2}S 1s{sup 2}2s{sup 1} ground state.

  12. Insight into the roles of structures and energy levels of mono- and bis-β-diketones on sensitizing Nd(iii) NIR-luminescence.

    PubMed

    Li, Bing; Li, Hongfeng; Chen, Peng; Sun, Wenbin; Wang, Cheng; Gao, Ting; Yan, Pengfei

    2016-07-28

    Three neodymium complexes Nd(TTA)3(DMSO)2 (1, TTA = 2-thenoyltrifluoroacetone), Nd2(BDT)3(DMSO)6 (2, BDT = bis(4,4,4-trifluoro-1,3-dioxobutyl)thiophene) and Nd2(BTT)3(DMSO)4 (3, BTT = bis(4,4,4-trifluoro-1,3-dioxobutyl)(2,2'-bithiophene)) constructed from three thiophene-based β-diketonate ligands, were prepared for the purpose of building the relationships between the structures, energy levels of the complexes and NIR luminescence properties of Nd(iii) ions. X-ray crystallographical analysis reveals that complex 1 is a mononuclear structure, the central Nd(iii) ion is coordinated by eight oxygen atoms from three mono-β-diketones (TTA) and two DMSO, whereas, complexes 2 and 3 adopt triple-stranded dinuclear structures, in which the two Nd(iii) ions are wrapped by three bis-β-diketones, the central Nd(iii) ions are nine and eight coordinated by oxygen atoms from ligands and the coordinated DMSO molecules. The photophysical properties related to the electronic transition are characterized by the absorbance spectra, the excitation spectra, the phosphorescence spectra, the emission spectra, the emission quantum yields, and the emission lifetimes. The luminescence quantum yields experiment reveals that the dinuclear complexes (0.49% and 0.33% for 2 and 3) show higher luminescence efficiencies compared to the mononuclear complex 1 (0.22%). This enhancement is mainly attributed to their binuclear structures, which effectively represses the nonradiative transition caused by high-energy oscillators in ligands and/or solvents. On the other hand, the energy level matching also plays an important role in this enhancement. PMID:27346610

  13. Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species With Application to DSMC Simulations

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.

    2013-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for nearequilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion of the heating and is then compared to the total heating measured in flight.

  14. Photodetachment of gaseous multiply charged anions, copper phthalocyanine tetrasulfonate tetraanion: Tuning molecular electronic energy levels by charging and negative electron binding

    SciTech Connect

    Wang, X.B.; Ferris, K.; Wang, L.S.

    2000-01-13

    The authors report photodetachment photoelectron spectroscopy (PES) of gaseous copper phthalocyanine (CuPc) tetrasulfonate quadruply charged anions, [CuPc(SO{sub 3}){sub 4}]{sup 4{minus}}, and its monoprotonated and -sodiumated triply charged anions, [CuPc(SO{sub 3}){sub 4}H]{sup 3{minus}} and [CuPc(SO{sub 3}){sub 4}Na]{sup 3{minus}}. The [CuPc(SO{sub 3}){sub 4}]{sup 4{minus}} tetraanion was found to possess a negative electron binding energy of {minus}0.9 eV, whereas the trianions have binding energies of 1.0 and 1.2 eV for the sodiumated and protonated species, respectively. The PES spectral features of the three multiply charged anions were observed to be similar to that of the parent CuPc neutral molecule, except that the anions have lower binding energies due to the presence of the negative charges ({minus}SO{sub 3}{sup {minus}}). The data thus suggested a stepwise tuning of the molecular electronic energy levels of the CuPc molecule through charging, wherein the molecular orbital energies of the parent molecule were systematically pushed up by the negative charges. The authors further carried out semiempirical calculations, which provided insight into the nature of the localized charges on the peripheral {minus}SO{sub 3}{sup {minus}} groups and the intramolecular electrostatic interactions in the multiply charged anions and confirmed the interpretation of the stepwise tuning of molecular energy levels by charging. Photon energy-dependent studies revealed the effects of the repulsive Coulomb barriers on the photodetachment PES spectra of the multiply charged anions. The barrier heights were estimated to be about 3.5 and 2.5 eV for the tetra- and trianions, respectively. The authors also observed excited states for the multiply charged anions and resonant tunneling through the repulsive Coulomb barriers via the excited states.

  15. Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species with Application to DSMC Simulations

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.

    2014-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for near-equilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion.

  16. Effect of protein and energy levels in sweet sorghum bagasse leaf residue-based diets on the performance of growing Deccani lambs.

    PubMed

    Yerradoddi, Ramana Reddy; Khan, Arif Ali; Mallampalli, Saibutcha Rao; Devulapalli, Ravi; Kodukula, Prasad; Blümmel, Michael

    2015-04-01

    Sweet sorghum bagasse with leaf residue (SSBLR) based complete diets with high or low protein and high- or low-energy levels were evaluated in a 60-day growth trial using growing sheep. Twenty-eight Deccani ram lambs were divided into four groups (16.0 ± 0.59 kg) of seven each and fed low-protein high-/low-energy and high-protein high-/low-energy diets ad lib. Average daily gain (g; P < 0.05) and feed efficiency (P < 0.01) were significantly higher in lambs fed high energy than those with low-energy diets, and cost per kg gain ($) was significantly lower (P < 0.05) in low protein than high-protein diets. Dry matter intake (DMI) (g/day) was not significantly affected either by protein or energy level in the diet, but dry matter (DM), organic matter (OM), protein, and neutral detergent fiber (NDF) digestibilities were higher significantly (P < 0.01) in high protein/energy diets than low protein/energy diets. Crude protein (CP) intake (g/day) was significantly (P < 0.001) higher in lambs fed high protein than low-protein diets. However, N balance (g/day) was significantly (P < 0.001) higher in lambs fed low protein than high-protein diets. It is concluded that feeding of SSBLR-based diet with low protein (CP 12.9 %) and high energy (9.4 MJ metabolizable energy (ME)/kg DM) was recommended for better performance, nitrogen retention, and returns from growing Deccani ram lambs.

  17. Use of nonlinear programming to optimize performance response to energy density in broiler feed formulation.

    PubMed

    Guevara, V R

    2004-02-01

    A nonlinear programming optimization model was developed to maximize margin over feed cost in broiler feed formulation and is described in this paper. The model identifies the optimal feed mix that maximizes profit margin. Optimum metabolizable energy level and performance were found by using Excel Solver nonlinear programming. Data from an energy density study with broilers were fitted to quadratic equations to express weight gain, feed consumption, and the objective function income over feed cost in terms of energy density. Nutrient:energy ratio constraints were transformed into equivalent linear constraints. National Research Council nutrient requirements and feeding program were used for examining changes in variables. The nonlinear programming feed formulation method was used to illustrate the effects of changes in different variables on the optimum energy density, performance, and profitability and was compared with conventional linear programming. To demonstrate the capabilities of the model, I determined the impact of variation in prices. Prices for broiler, corn, fish meal, and soybean meal were increased and decreased by 25%. Formulations were identical in all other respects. Energy density, margin, and diet cost changed compared with conventional linear programming formulation. This study suggests that nonlinear programming can be more useful than conventional linear programming to optimize performance response to energy density in broiler feed formulation because an energy level does not need to be set.

  18. Degenerate density perturbation theory

    NASA Astrophysics Data System (ADS)

    Palenik, Mark C.; Dunlap, Brett I.

    2016-09-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of Nd degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X α exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first- through third-order energies as a function of α , with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  19. Extracting primordial density fluctuations

    PubMed

    Gawiser; Silk

    1998-05-29

    The combination of detections of anisotropy in cosmic microwave background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the cold + hot dark matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos.

  20. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  1. Determination of the atomic density of rubidium-87

    NASA Astrophysics Data System (ADS)

    Zhao, Meng; Zhang, Kai; Chen, Li-Qing

    2015-09-01

    Atomic density is a basic and important parameter in quantum optics, nonlinear optics, and precision measurement. In the past few decades, several methods have been used to measure atomic density, such as thermionic effect, optical absorption, and resonance fluorescence. The main error of these experiments stemmed from depopulation of the energy level, self-absorption, and the broad bandwidth of the laser. Here we demonstrate the atomic density of 87Rb vapor in paraffin coated cell between 297 K and 334 K mainly using fluorescence measurement. Optical pumping, anti-relaxation coating, and absorption compensation approaches are used to decrease measurement error. These measurement methods are suitable for vapor temperature at dozens of degrees. The fitting function for the experimental data of 87Rb atomic density is given. Project supported by the Natural Science Foundation of China (Grant Nos. 11274118 and 11474095), the Innovation Program of Shanghai Municipal Education Commission of China (Grant No. 13ZZ036), and the Fundamental Research Funds for the Central Universities of China.

  2. Electron Density Measurement of Argon Containing Plasmas by Saturation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nishiyama, S.; Wang, H.; Tomioka, S.; Sasaki, K.

    2014-10-01

    Langmuir probes are widely used for electron density measurements in plasmas. However, the use of a conventional probe should be avoided in a plasma which needs high purity because of the possibility of contamination. Optical measurements are suitable for these plasmas. In this work, we applied saturation spectroscopy to the electron density measurement. The peak height of the saturation spectrum is affected by the relaxation frequency of the related energy levels. In the case of the metastable levels of argon, the electron impact quenching rate, which is proportional to the electron density, is the dominant factor. In our experiments, an inductively coupled plasma source and a tunable cw diode laser were used. The frequency of the laser was scanned over the Doppler width of the 4 s[3/ 2 ] 2 o - 4 p[ 3 / 2 ] 2 (763.51 nm) transition. The experimental saturation spectrum was composed of a sharp Lorentzian peak and a broad base component, which was caused by velocity changing collisions. We deduced a new relationship between the saturation parameter and the measured saturated absorption spectrum with considering velocity changing collisions. We confirmed a linear relationship, which was expected theoretically, between the inverse of the saturation parameter and the electron density. Part of this work is supported by JSPS KAKENHI Grant Number 24540529.

  3. Gedanken densities and exact constraints in density functional theory

    SciTech Connect

    Perdew, John P.; Ruzsinszky, Adrienn; Sun, Jianwei; Burke, Kieron

    2014-05-14

    Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGA’s. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.

  4. The electronic properties of noble metal doped silicon nanocrystals using hybrid density functional theory

    NASA Astrophysics Data System (ADS)

    Mayfield, Cedric Leon

    One of the most challenging issues in semiconductor physics is to engineer band structures for a particular device. Contemporary photovoltaic (PV) and photoelectrochemical (PEC) devices rely on defect energy levels and nano-scaling to customize their band structures. As the length scale of a material becomes comparable to the exciton Bohr radius the free particle behavior of charge carriers transition to bound states where energy levels are quantized. In this thesis, hybrid density functional theory has been used to study the electronic properties of silicon nanocrystals (SiNCs) having 75, 150 and 300 silicon atoms. The atomic coordinates were defined by two geometries (diamond and wurtzite) of bulk phase silicon. The global minimum energy structures for both geometries at each size were found for particular variation on magnetic moments, dopant, dopant position, and surface passivation with hydrogen. We report our results on bond lengths, binding energies, formation energies, HOMO-LUMO gaps, and density of states. We also report results on electronic occupations derived from Mulliken population analysis. Our results show that the SiNCs have tunable HOMO-LUMO gaps with respect to size and that the inclusion of noble metals produces inter-gap defect levels. In addition, we have found that hydrogen passivation affected the doping behavior significantly. Contrary to the general expectation, hydrogen passivation contributed to the energy levels near the highest occupied orbital. Overall, our results suggest the SiNCs can be used to construct optimal photovoltaic applications or used individually as photocatalysts.

  5. Density Gradients in Chemistry Teaching

    ERIC Educational Resources Information Center

    Miller, P. J.

    1972-01-01

    Outlines experiments in which a density gradient might be used to advantage. A density gradient consists of a column of liquid, the composition and density of which varies along its length. The procedure can be used in analysis of solutions and mixtures and in density measures of solids. (Author/TS)

  6. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  7. Density Functional Plus Dynamical Mean Field Theory of Correlated Oxides

    NASA Astrophysics Data System (ADS)

    Millis, Andrew

    2015-03-01

    The density functional plus dynamical mean field method is outlined and a few recent successes including applications to spin crossover molecules, oxide superlattices and metal-insulator transitions in bulk transition metals are outlined. Insights from the method into the essential role played by lattice distortions (both rotations and bond length changes) in determining the phase diagrams of correlated materials are presented. The key theoretical issue of the double counting correction is outlined, different approaches are compared, and a connection to the energy level differences between strongly and weakly correlated orbitals is presented. Charge transfer across oxide interfaces shown to depend crucially on the double counting correction, suggesting that experiments on oxide superlattices may provide insights into this important problem. Future directions are discussed. This work is performed in collaboration with Jia Chen, Hung Dang, Hyowon Park and Chris Marianetti. This research supported by the DOE Office of Science, Grant ER 046169.

  8. Fundamental gap of molecular crystals via constrained density functional theory

    NASA Astrophysics Data System (ADS)

    Droghetti, Andrea; Rungger, Ivan; Das Pemmaraju, Chaitanya; Sanvito, Stefano

    2016-05-01

    The energy gap of a molecular crystal is one of the most important properties since it determines the crystal charge transport when the material is utilized in electronic devices. This is, however, a quantity difficult to calculate and standard theoretical approaches based on density functional theory (DFT) have proven unable to provide accurate estimates. In fact, besides the well-known band-gap problem, DFT completely fails in capturing the fundamental gap reduction occurring when molecules are packed in a crystal structures. The failure has to be associated with the inability of describing the electronic polarization and the real space localization of the charged states. Here we describe a scheme based on constrained DFT, which can improve upon the shortcomings of standard DFT. The method is applied to the benzene crystal, where we show that accurate results can be achieved for both the band gap and also the energy level alignment.

  9. Correlation of materials properties with the atomic density concept

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Based on the hypothesis that the number of atoms per unit volume, accurately calculable for any substance of known real density and chemical composition, various characterizing parameters (energy levels of electrons interacting among atoms of the same or different kinds, atomic mass, bond intensity) were chosen for study. A multiple exponential equation was derived to express the relationship. Various properties were examined, and correlated with the various parameters. Some of the properties considered were: (1) heat of atomization, (2) boiling point, (3) melting point, (4) shear elastic modulus of cubic crystals, (5) thermal conductivity, and (6) refractive index for transparent substances. The solid elements and alkali halides were the materials studied. It is concluded that the number of different properties can quantitively be described by a common group of parameters for the solid elements, and a wide variety of compounds.

  10. Highly Accurate Potential Energy Surface, Dipole Moment Surface, Rovibrational Energy Levels, and Infrared Line List for (32)S(16)O2 up to 8000 cm(exp -1)

    NASA Technical Reports Server (NTRS)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2014-01-01

    A purely ab initio potential energy surface (PES) was refined with selected (32)S(16)O2 HITRAN data. Compared to HITRAN, the root-mean-squares error (RMS) error for all J=0-80 rovibrational energy levels computed on the refined PES (denoted Ames-1) is 0.013 cm(exp -1). Combined with a CCSD(T)/aug-cc-pV(Q+d)Z dipole moment surface (DMS), an infrared (IR) line list (denoted Ames-296K) has been computed at 296K and covers up to 8,000 cm(exp -1). Compared to the HITRAN and CDMS databases, the intensity agreement for most vibrational bands is better than 85-90%. Our predictions for (34)S(16)O2 band origins, higher energy (32)S(16)O2 band origins and missing (32)S(16)O2 IR bands have been verified by most recent experiments and available HITRAN data. We conclude that the Ames-1 PES is able to predict (32/34)S(16)O2 band origins below 5500 cm(exp -1) with 0.01-0.03 cm(exp -1) uncertainties, and the Ames-296K line list provides continuous, reliable and accurate IR simulations. The Ka-dependence of both line position and line intensity errors is discussed. The line list will greatly facilitate SO2 IR spectral experimental analysis, as well as elimination of SO2 lines in high-resolution astronomical observations.

  11. Oligomycin A-induced inhibition of mitochondrial ATP-synthase activity suppresses boar sperm motility and in vitro capacitation achievement without modifying overall sperm energy levels.

    PubMed

    Ramió-Lluch, Laura; Yeste, Marc; Fernández-Novell, Josep M; Estrada, Efrén; Rocha, Luiz; Cebrián-Pérez, José A; Muiño-Blanco, Teresa; Concha, Ilona I; Ramírez, Alfredo; Rodríguez-Gil, Joan E

    2014-01-01

    Incubation of boar spermatozoa in a capacitation medium with oligomycin A, a specific inhibitor of the F0 component of the mitochondrial ATP synthase, induced an immediate and almost complete immobilisation of cells. Oligomycin A also inhibited the ability of spermatozoa to achieve feasible in vitro capacitation (IVC), as measured through IVC-compatible changes in motility patterns, tyrosine phosphorylation levels of the acrosomal p32 protein, membrane fluidity and the ability of spermatozoa to achieve subsequent, progesterone-induced in vitro acrosome exocytosis (IVAE). Both inhibitory effects were caused without changes in the rhythm of O2 consumption, intracellular ATP levels or mitochondrial membrane potential (MMP). IVAE was accompanied by a fast and intense peak in O2 consumption and ATP levels in control spermatozoa. Oligomycin A also inhibited progesterone-induced IVAE as well as the concomitant peaks of O2 consumption and ATP levels. The effect of oligomycin on IVAE was also accompanied by concomitant alterations in the IVAE-induced changes on intracellular Ca(2+) levels and MMP. Our results suggest that the oligomycin A-sensitive mitochondrial ATP-synthase activity is instrumental in the achievement of an adequate boar sperm motion pattern, IVC and IVAE. However, this effect seems not to be linked to changes in the overall maintenance of adequate energy levels in stages other than IVAE.

  12. Tuning of the stability and energy levels of singlet exciton fission relevant excited states of pentacenes by site-specific substitution.

    PubMed

    Shen, Li; Chen, Yuhan; Li, Xiyou; Li, Chungang

    2016-05-01

    Pentacene crystals or oligomers undergo efficient singlet exciton fission (SF) after photo-excitation, which is expected to be useful in overcoming the Shockley-Queisser theoretical limit of solar cells. However, pentacenes are extremely unstable in air due to oxidation by oxygen. In this work, we designed a group of pentacene compounds with different substituents at different positions. The energy levels of HOMO and LUMO, which are believed to be closely related to the stability of pentacene, were calculated. The relationship between the molecular structure and the stability was discussed. The driving force for SF was estimated from the difference between the energy of first singlet excited state (E(S1)) and the energy of two triplet excited state (2×E(T1)) following equation E(S1)-2E(T1). Strong electron-withdrawing groups can stabilize pentacene compounds significantly, but induce a decrease on the driving force of SF slightly. Electron-donating groups destabilize the pentacene compounds dramatically and hence the introduction of electron donating groups to pentacene is not recommended. TIPS is an ideal group to improve the stability of pentacene compounds. TIPS does not change the driving force of SF significantly. Sulfur containing groups are also efficient on stabilizing pentacene compounds. These groups increase the driving force of SF at ɑ position, and recued the driving force of SF at other positions. The results of this work provide a theoretical ground for rational design of new SF molecules based on pentacenes. PMID:27131283

  13. Quantum and classical dynamics of H + CaCl(X (2)Σ(+)) → HCl + Ca((1)S) reaction and vibrational energy levels of the HCaCl complex.

    PubMed

    Tan, Rui Shan; Zhai, Huan Chen; Gao, Feng; Tong, Dianmin; Lin, Shi Ying

    2016-06-21

    We carried out accurate quantum wave packet as well as quasi-classical trajectory (QCT) calculations for H + CaCl (νi = 0, ji = 0) reaction occurring on an adiabatic ground state using the recent ab initio potential energy surface to obtain the quantum and QCT reaction probabilities for several partial waves (J = 0, 10, and 20) as well as state resolved QCT integral and differential cross sections. The complete list of vibrational energy levels supported by the intermediate HCaCl complex is also obtained using the Lanczos algorithm. The QCT reaction probabilities show excellent agreement with the quantum ones except for the failure in reproducing the highly oscillatory resonance structure. Despite the fact that the reaction is exothermic and the existence of a barrier that is energetically lower than the bottom of the reactant valley, the reaction probability for J = 0 shows threshold-like behavior and the reactivity all through the energies is very low (<0.1). The dynamical features at two different energy regions (<0.35 eV and >0.35 eV) are found to be different drastically from each other. The analyses of these results suggest that the reaction is governed by one of the two different types of reaction mechanism, one is the direct mechanism at the high energy region and the other is the indirect mechanism at the low energy region by which the reaction proceeds through the long-lived intermediate complex followed by a statistical dissociation into asymptotic channels.

  14. Tuning of the stability and energy levels of singlet exciton fission relevant excited states of pentacenes by site-specific substitution.

    PubMed

    Shen, Li; Chen, Yuhan; Li, Xiyou; Li, Chungang

    2016-05-01

    Pentacene crystals or oligomers undergo efficient singlet exciton fission (SF) after photo-excitation, which is expected to be useful in overcoming the Shockley-Queisser theoretical limit of solar cells. However, pentacenes are extremely unstable in air due to oxidation by oxygen. In this work, we designed a group of pentacene compounds with different substituents at different positions. The energy levels of HOMO and LUMO, which are believed to be closely related to the stability of pentacene, were calculated. The relationship between the molecular structure and the stability was discussed. The driving force for SF was estimated from the difference between the energy of first singlet excited state (E(S1)) and the energy of two triplet excited state (2×E(T1)) following equation E(S1)-2E(T1). Strong electron-withdrawing groups can stabilize pentacene compounds significantly, but induce a decrease on the driving force of SF slightly. Electron-donating groups destabilize the pentacene compounds dramatically and hence the introduction of electron donating groups to pentacene is not recommended. TIPS is an ideal group to improve the stability of pentacene compounds. TIPS does not change the driving force of SF significantly. Sulfur containing groups are also efficient on stabilizing pentacene compounds. These groups increase the driving force of SF at ɑ position, and recued the driving force of SF at other positions. The results of this work provide a theoretical ground for rational design of new SF molecules based on pentacenes.

  15. Assisted extraction of the energy level spacings and lever arms in direct current bias measurements of one-dimensional quantum wires, using an image recognition routine

    SciTech Connect

    Lesage, A. A. J. Smith, L. W. Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Smith, C. G.; Al-Taie, H.; Kelly, M. J.; See, P.

    2015-01-07

    A multiplexer technique is used to individually measure an array of 256 split gates on a single GaAs/AlGaAs heterostructure. This results in the generation of large volumes of data, which requires the development of automated data analysis routines. An algorithm is developed to find the spacing between discrete energy levels, which form due to transverse confinement from the split gate. The lever arm, which relates split gate voltage to energy, is also found from the measured data. This reduces the time spent on the analysis. Comparison with estimates obtained visually shows that the algorithm returns reliable results for subband spacing of split gates measured at 1.4 K. The routine is also used to assess direct current bias spectroscopy measurements at lower temperatures (50 mK). This technique is versatile and can be extended to other types of measurements. For example, it is used to extract the magnetic field at which Zeeman-split 1D subbands cross one another.

  16. Highly accurate potential energy surface, dipole moment surface, rovibrational energy levels, and infrared line list for ³²S¹⁶O₂ up to 8000 cm⁻¹.

    PubMed

    Huang, Xinchuan; Schwenke, David W; Lee, Timothy J

    2014-03-21

    A purely ab initio potential energy surface (PES) was refined with selected (32)S(16)O2 HITRAN data. Compared to HITRAN, the root-mean-squares error (σ(RMS)) for all J = 0-80 rovibrational energy levels computed on the refined PES (denoted Ames-1) is 0.013 cm(-1). Combined with a CCSD(T)/aug-cc-pV(Q+d)Z dipole moment surface (DMS), an infrared (IR) line list (denoted Ames-296K) has been computed at 296 K and covers up to 8000 cm(-1). Compared to the HITRAN and CDMS databases, the intensity agreement for most vibrational bands is better than 85%-90%. Our predictions for (34)S(16)O2 band origins, higher energy (32)S(16)O2 band origins and missing (32)S(16)O2 IR bands have been verified by most recent experiments and available HITRAN data. We conclude that the Ames-1 PES is able to predict (32/34)S(16)O2 band origins below 5500 cm(-1) with 0.01-0.03 cm(-1) uncertainties, and the Ames-296K line list provides continuous, reliable and accurate IR simulations. The K(a)-dependence of both line position and line intensity errors is discussed. The line list will greatly facilitate SO2 IR spectral experimental analysis, as well as elimination of SO2 lines in high-resolution astronomical observations. PMID:24655184

  17. Location of trivalent lanthanide dopant energy levels in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3}

    SciTech Connect

    Retot, H.; Viana, B.; Bessiere, A.; Galtayries, A.

    2011-06-15

    The location of Ln{sup 3+} dopant energy levels relative to bands in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} was studied. A several-steps analysis of XPS measurements on heavy lanthanides sesquioxides Ln{sub 2}O{sub 3} (Ln = Gd, Tb, Dy, Er, Tm, Yb, Lu) and on Sc{sub 2}O{sub 3} and Y{sub 2}O{sub 3} reference materials were used to locate Ln{sup 3+} dopant ground state relative to the top of the valence band in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} within an error bar of {+-}0.4 eV. The agreement between XPS data and model was found improved relative to previous studies. When compared to XPS analysis, prediction based on optical absorption shows a slight underestimation attributed to the lack of precision in Ce{sup 4+} charge transfer band measurement.

  18. Generating random density matrices

    NASA Astrophysics Data System (ADS)

    Życzkowski, Karol; Penson, Karol A.; Nechita, Ion; Collins, Benoît

    2011-06-01

    We study various methods to generate ensembles of random density matrices of a fixed size N, obtained by partial trace of pure states on composite systems. Structured ensembles of random pure states, invariant with respect to local unitary transformations are introduced. To analyze statistical properties of quantum entanglement in bi-partite systems we analyze the distribution of Schmidt coefficients of random pure states. Such a distribution is derived in the case of a superposition of k random maximally entangled states. For another ensemble, obtained by performing selective measurements in a maximally entangled basis on a multi-partite system, we show that this distribution is given by the Fuss-Catalan law and find the average entanglement entropy. A more general class of structured ensembles proposed, containing also the case of Bures, forms an extension of the standard ensemble of structureless random pure states, described asymptotically, as N → ∞, by the Marchenko-Pastur distribution.

  19. Low density microcellular foams

    DOEpatents

    LeMay, J.D.

    1991-11-19

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.

  20. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1991-01-01

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  1. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1992-01-01

    Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  2. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    The outside pressure shell for the Variable-Density Tunnel (VDT). The shell, or 'tank' as it was called, was built in the Newport News Shipyard and traveled by barge to Langley. The tank could withstand a working pressure of 21 atmospheres. Elton Miller described it in NACA TR No. 227 (pp. 411-412): 'It is built of steel plates lapped and riveted according to the usual practice in steam boiler construction, although, because of the size of the tank and the high working pressure, the construction is unusually heavy. There is a cylindrical body portion of 2-1/8 inch (53.98 millimeters) steel plate with hemispherical ends 1-1/4 inches (31.75 millimeters) in thickness.'

  3. Interstellar Electron Density Spectra

    NASA Astrophysics Data System (ADS)

    Lambert, Hendrick Clark

    This study concerns the investigation of the form of the wavenumber spectrum of the Galactic electron density fluctuations through an examination of the scattering of the radio pulses emitted by pulsars as they propagate through the diffuse ionized interstellar gas. A widely used model for the electron density spectrum is based on the simple power-law: Pne(q)∝ q-β, where β = 11/3 is usually assumed, corresponding to Kolmogorov's turbulence spectrum. The simple Kolmogorov model provides satisfactory agreement for observations along many lines of sight; however, major inconsistencies remain. The inconsistencies suggest that an increase in the ratio of the power between the high (10-8[ m]-1≤ q<=10-7[ m]-1) and low (10-13[ m]-1≤ q<=10-12[ m]-1) wavenumbers is needed. This enhancement in the ratio can in turn be achieved by either including an inner scale, corresponding to a dissipation scale for the turbulent cascade, in the Kolmogorov spectrum or by considering steeper spectra. Spectra with spectral exponents β > 4 have been in general rejected based on observations of pulsar refractive scintillations. The special case of β = 4 has been given little attention and is analyzed in detail. Physically, this 'β = 4' model corresponds to the random distribution, both in location and orientation, of discrete objects with relatively sharp boundaries across the line of sight. An outer scale is included in the model to account for the average size of such objects. We compare the predictions of the inner-scale and β = 4 models both with published observations and observations we made as part of this investigation. We conclude that the form of the wavenumber spectrum is dependent on the line of sight. We propose a composite spectrum featuring a uniform background turbulence in presence of randomly distributed discrete objects, as modeled by the β = model.

  4. Low density microcellular foams

    DOEpatents

    Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.

    1985-10-02

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.

  5. Low density microcellular foams

    DOEpatents

    Aubert, James H.; Clough, Roger L.; Curro, John G.; Quintana, Carlos A.; Russick, Edward M.; Shaw, Montgomery T.

    1987-01-01

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.

  6. Energy level of the Si-related DX-center in (Al{sub y}Ga{sub 1−y}){sub 1−x}In{sub x}As

    SciTech Connect

    Heckelmann, Stefan Lackner, David; Bett, Andreas W.

    2015-03-09

    For the quaternary material (Al{sub y}Ga{sub 1−y}){sub 1−x}In{sub x}As, the energy level of the silicon-related deep electron trap known as the DX-center is calculated. In addition, the composition range y(x) is derived, for which the silicon-related DX-center level is below the conduction band minimum and thus electronically active. Eventually, the result of the calculation is compared with available measurement data, revealing good agreement regarding the composition when the DX-center energy level crosses the conduction band minimum.

  7. Quantum and classical dynamics of H + CaCl(X (2)Σ(+)) → HCl + Ca((1)S) reaction and vibrational energy levels of the HCaCl complex.

    PubMed

    Tan, Rui Shan; Zhai, Huan Chen; Gao, Feng; Tong, Dianmin; Lin, Shi Ying

    2016-06-21

    We carried out accurate quantum wave packet as well as quasi-classical trajectory (QCT) calculations for H + CaCl (νi = 0, ji = 0) reaction occurring on an adiabatic ground state using the recent ab initio potential energy surface to obtain the quantum and QCT reaction probabilities for several partial waves (J = 0, 10, and 20) as well as state resolved QCT integral and differential cross sections. The complete list of vibrational energy levels supported by the intermediate HCaCl complex is also obtained using the Lanczos algorithm. The QCT reaction probabilities show excellent agreement with the quantum ones except for the failure in reproducing the highly oscillatory resonance structure. Despite the fact that the reaction is exothermic and the existence of a barrier that is energetically lower than the bottom of the reactant valley, the reaction probability for J = 0 shows threshold-like behavior and the reactivity all through the energies is very low (<0.1). The dynamical features at two different energy regions (<0.35 eV and >0.35 eV) are found to be different drastically from each other. The analyses of these results suggest that the reaction is governed by one of the two different types of reaction mechanism, one is the direct mechanism at the high energy region and the other is the indirect mechanism at the low energy region by which the reaction proceeds through the long-lived intermediate complex followed by a statistical dissociation into asymptotic channels. PMID:27224034

  8. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    NASA Astrophysics Data System (ADS)

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M. A.; Ahamed, Maqusood

    2015-09-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

  9. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    PubMed Central

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M.A.; Ahamed, Maqusood

    2015-01-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33–55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved. PMID:26347142

  10. Density sensitive hashing.

    PubMed

    Jin, Zhongming; Li, Cheng; Lin, Yue; Cai, Deng

    2014-08-01

    Nearest neighbor search is a fundamental problem in various research fields like machine learning, data mining and pattern recognition. Recently, hashing-based approaches, for example, locality sensitive hashing (LSH), are proved to be effective for scalable high dimensional nearest neighbor search. Many hashing algorithms found their theoretic root in random projection. Since these algorithms generate the hash tables (projections) randomly, a large number of hash tables (i.e., long codewords) are required in order to achieve both high precision and recall. To address this limitation, we propose a novel hashing algorithm called density sensitive hashing (DSH) in this paper. DSH can be regarded as an extension of LSH. By exploring the geometric structure of the data, DSH avoids the purely random projections selection and uses those projective functions which best agree with the distribution of the data. Extensive experimental results on real-world data sets have shown that the proposed method achieves better performance compared to the state-of-the-art hashing approaches.

  11. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1990-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  12. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1989-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  13. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  14. Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

    SciTech Connect

    Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo; Peng, Yingquan

    2013-12-28

    Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs.

  15. Whistler and FLR density calibration

    NASA Astrophysics Data System (ADS)

    Lichtenberger, János; Vellante, Massimo; Heilig, Balázs; Ferencz, Csaba; Regi, Mauro; Clilverd, Mark; Juhász, Lilla

    2014-05-01

    One of the major objective in PLASMON (http://plasmon.elte.hu) project is to provide plasma densities for data assimilative modeling of plasmasphere from two ground based measurements: whistlers and field line resonances (FLRs). The whistler inversion method used in this procedure includes various model, including wave propagation, magnetic field, field aligned density distribution and equatorial electron density models. The latter one is a special one used for multiple-path whistler groups. As one can obtain electron densities from whistler inversion and plasma mass densities from FLRs, the ion composition would be required to connect the to dataset (that are intended to use in the plasmasphere model), which is rarely known or available. Therefore we have developed a method for cross calibration of the data from two sources. It is based on physics based and experimental field aligned plasma density distribution models as well as on comparison with in situ wave and density (IMAGE and Van Allen Probes) measurements.

  16. Comparison of density determination of liquid samples by density meters

    NASA Astrophysics Data System (ADS)

    Buchner, C.; Wolf, H.; Vámossy, C.; Lorefice, S.; Lenard, E.; Spohr, I.; Mares, G.; Perkin, M.; Parlic-Risovic, T.; Grue, L.-L.; Tammik, K.; van Andel, I.; Zelenka, Z.

    2016-01-01

    Hydrostatic density determinations of liquids as reference material are mainly performed by National Metrology Institutes to provide means for calibrating or checking liquid density measuring instruments such as oscillation-type density meters. These density meters are used by most of the metrology institutes for their calibration and scientific work. The aim of this project was to compare the results of the liquid density determination by oscillating density meters of the participating laboratories. The results were linked to CCM.D.K-2 partly via Project EURAMET.M.D.K-2 (1019) "Comparison of liquid density standards" by hydrostatic weighing piloted by BEV in 2008. In this comparison pentadecane, water and of oil with a high viscosity were measured at atmospheric pressure using oscillation type density meter. The temperature range was from 15 °C to 40 °C. The measurement results were in some cases discrepant. Further studies, comparisons are essential to explore the capability and uncertainty of the density meters Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. NASA Ames's electric arc-driven shock tube facility and research on nonequilibrium phenomena in low density hypersonic flows

    NASA Technical Reports Server (NTRS)

    Sharma, Surendra P.

    1992-01-01

    Basic requirements for a ground test facility simulating low density hypersonic flows are discussed. Such facilities should be able to produce shock velocities in the range of 10-17 km/sec in an initial pressure of 0.010 to 0.050 Torr. The facility should be equipped with diagnostics systems to be able to measure the emitted radiation, characteristic temperatures and populations in various energy levels. In the light of these requirements, NASA Ames's electric arc-driven low density shock tube facility is described and available experimental diagnostics systems and computational tools are discussed.

  18. Torsional energy levels of CH{sub 3}OH{sup +}/CH{sub 3}OD{sup +}/CD{sub 3}OD{sup +} studied by zero-kinetic energy photoelectron spectroscopy and theoretical calculations

    SciTech Connect

    Dai, Zuyang; Gao, Shuming; Wang, Jia; Mo, Yuxiang

    2014-10-14

    The torsional energy levels of CH{sub 3}OH{sup +}, CH{sub 3}OD{sup +}, and CD{sub 3}OD{sup +} have been determined for the first time using one-photon zero kinetic energy photoelectron spectroscopy. The adiabatic ionization energies for CH{sub 3}OH, CH{sub 3}OD, and CD{sub 3}OD are determined as 10.8396, 10.8455, and 10.8732 eV with uncertainties of 0.0005 eV, respectively. Theoretical calculations have also been performed to obtain the torsional energy levels for the three isotopologues using a one-dimensional model with approximate zero-point energy corrections of the torsional potential energy curves. The calculated values are in good agreement with the experimental data. The barrier height of the torsional potential energy without zero-point energy correction was calculated as 157 cm{sup −1}, which is about half of that of the neutral (340 cm{sup −1}). The calculations showed that the cation has eclipsed conformation at the energy minimum and staggered one at the saddle point, which is the opposite of what is observed in the neutral molecule. The fundamental C–O stretch vibrational energy level for CD{sub 3}OD{sup +} has also been determined. The energy levels for the combinational excitation of the torsional vibration and the fundamental C–O stretch vibration indicate a strong torsion-vibration coupling.

  19. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  20. Characterization of heterojunctions via x-ray and uv photoemission spectroscopy: energy level implications for single and mixed monolayer SAMs, cadmium selenide nanoparticle films, and organic semiconductor depositions

    NASA Astrophysics Data System (ADS)

    Graham, Amy L.

    transfer states of ZnPc did not favor energy level alignment on the SAM/Au substrates used; C60 demonstrated vacuum level shifts on C15 and C12ph alkanethiol monolayers consistent with the interface charge transfer (ICT) model. These results provide credibility to models recently demonstrated in the literature for other passivated metal surfaces, and include the viability of SAMs in these discussions.

  1. Spectral density of Cooper pairs in two level quantum dot-superconductors Josephson junction

    NASA Astrophysics Data System (ADS)

    Dhyani, A.; Rawat, P. S.; Tewari, B. S.

    2016-09-01

    In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.

  2. Density Fluctuations in Liquid Water

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Tse, John S.

    2011-01-01

    The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

  3. Symmetry energy, its density slope, and neutron-proton effective mass splitting at normal density extracted from global nucleon optical potentials

    SciTech Connect

    Xu Chang; Li Baoan; Chen Liewen

    2010-11-15

    Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy E{sub sym}({rho}) and its density slope L({rho}) at normal density {rho}{sub 0} are completely determined by the nucleon global optical potentials. The latter can be extracted directly from nucleon-nucleus scatterings, (p,n) charge-exchange reactions, and single-particle energy levels of bound states. Averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of E{sub sym}({rho}{sub 0})=31.3 MeV and L({rho}{sub 0})=52.7 MeV are simultaneously obtained. Moreover, the corresponding neutron-proton effective mass splitting in neutron-rich matter of isospin asymmetry {delta} is estimated to be (m{sub n}{sup *}-m{sub p}{sup *})/m=0.32{delta}.

  4. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures. PMID:26764847

  5. Density waves in granular flow

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Flekkøy, E.; Nagel, K.; Peng, G.; Ristow, G.

    Ample experimental evidence has shown the existence of spontaneous density waves in granular material flowing through pipes or hoppers. Using Molecular Dynamics Simulations we show that several types of waves exist and find that these density fluctuations follow a 1/f spectrum. We compare this behaviour to deterministic one-dimensional traffic models. If positions and velocities are continuous variables the model shows self-organized criticality driven by the slowest car. We also present Lattice Gas and Boltzmann Lattice Models which reproduce the experimentally observed effects. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow.

  6. SOP - Determination of Requirement Density

    SciTech Connect

    Reynolds, John G.; Martz, Jr., Harry E.

    2010-10-26

    The purpose of this Standard Operating Procedure (SOP) is to give guidelines on how to determine the density of a sample that will be used as the requirement density. This will be the requirement density of record for the specimens examined by Micro CT and EDS measurements. This density will then be set as the formulation requirement for radiography measurements. This SOP is referred to in TP 48— Preparation of Hydrogen Peroxide/Icing Sugar Specimens for X-ray Measurements by J. G. Reynolds and H. E. Martz.

  7. The surface density of haloes

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.; Lee, Xi-Guo

    We study the correlation between the central surface density and the core radius of the dark matter haloes of galaxies and clusters of galaxies. We find that the surface density within the halo characteristic radius r* is not a universal quantity as claimed by some authors (e.g., Milgrom 2009), but it correlates with several physical quantities (e.g., the halo mass M200, and the magnitude MB). The slope of the surface density-mass relation is 0.18 ± 0.05, leaving small room to the possibility of a constant surface density. Finally, we compare the results with MOND predictions.

  8. Density Estimation with Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Macready, William G.

    2003-01-01

    We present a new method for density estimation based on Mercer kernels. The density estimate can be understood as the density induced on a data manifold by a mixture of Gaussians fit in a feature space. As is usual, the feature space and data manifold are defined with any suitable positive-definite kernel function. We modify the standard EM algorithm for mixtures of Gaussians to infer the parameters of the density. One benefit of the approach is it's conceptual simplicity, and uniform applicability over many different types of data. Preliminary results are presented for a number of simple problems.

  9. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures.

  10. Current density and state density in diluted magnetic semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Pérez Merchancano, S. T.; Paredes Gutiérrez, H.; Zuñiga, J. A.

    2016-02-01

    We study in this paper the spin-polarized current density components in diluted magnetic semiconductor tunnelling diodes with different sample geometries. We calculate the resonant JxV and the density of states. The differential conductance curves are analyzed as functions of the applied voltage and the magnetic potential strength induced by the magnetic ions.

  11. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    NASA Astrophysics Data System (ADS)

    van Dam, Hubertus J. J.

    2016-05-01

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractional occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Finally, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.

  12. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    DOE PAGESBeta

    Hubertus J. J. van Dam

    2016-05-23

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractionalmore » occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.« less

  13. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  14. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  15. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  16. Density-orbital embedding theory

    SciTech Connect

    Gritsenko, O. V.; Visscher, L.

    2010-09-15

    In the article density-orbital embedding (DOE) theory is proposed. DOE is based on the concept of density orbital (DO), which is a generalization of the square root of the density for real functions and fractional electron numbers. The basic feature of DOE is the representation of the total supermolecular density {rho}{sub s} as the square of the sum of the DO {phi}{sub a}, which represents the active subsystem A and the square root of the frozen density {rho}{sub f} of the environment F. The correct {rho}{sub s} is obtained with {phi}{sub a} being negative in the regions in which {rho}{sub f} might exceed {rho}{sub s}. This makes it possible to obtain the correct {rho}{sub s} with a broad range of the input frozen densities {rho}{sub f} so that DOE resolves the problem of the frozen-density admissibility of the current frozen-density embedding theory. The DOE Euler equation for the DO {phi}{sub a} is derived with the characteristic embedding potential representing the effect of the environment. The DO square {phi}{sub a}{sup 2} is determined from the orbitals of the effective Kohn-Sham (KS) system. Self-consistent solution of the corresponding one-electron KS equations yields not only {phi}{sub a}{sup 2}, but also the DO {phi}{sub a} itself.

  17. Insulin Sensitivity in Adipose and Skeletal Muscle Tissue of Dairy Cows in Response to Dietary Energy Level and 2,4-Thiazolidinedione (TZD).

    PubMed

    Hosseini, Afshin; Tariq, Muhammad Rizwan; Trindade da Rosa, Fernanda; Kesser, Julia; Iqbal, Zeeshan; Mora, Ofelia; Sauerwein, Helga; Drackley, James K; Trevisi, Erminio; Loor, Juan J

    2015-01-01

    The effects of dietary energy level and 2,4-thiazolidinedione (TZD) injection on feed intake, body fatness, blood biomarkers and TZD concentrations, genes related to insulin sensitivity in adipose tissue (AT) and skeletal muscle, and peroxisome proliferator-activated receptor gamma (PPARG) protein in subcutaneous AT (SAT) were evaluated in Holstein cows. Fourteen nonpregnant nonlactating cows were fed a control low-energy (CON, 1.30 Mcal/kg) diet to meet 100% of estimated nutrient requirements for 3 weeks, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg) and half of the cows continued on CON for 6 weeks. All cows received an intravenous injection of TZD starting 2 weeks after initiation of dietary treatments and for an additional 2 weeks, which served as the washout period. Cows fed OVE had greater energy intake and body mass than CON, and TZD had no effect during the administration period. The OVE cows had greater TZD clearance rate than CON cows. The lower concentration of nonesterified fatty acids (NEFA) and greater concentration of insulin in blood of OVE cows before TZD injection indicated positive energy balance and higher insulin sensitivity. Administration of TZD increased blood concentrations of glucose, insulin, and beta-hydroxybutyrate (BHBA) at 2 to 4 weeks after diet initiation, while the concentration of NEFA and adiponectin (ADIPOQ) remained unchanged during TZD. The TZD upregulated the mRNA expression of PPARG and its targets FASN and SREBF1 in SAT, but also SUMO1 and UBC9 which encode sumoylation proteins known to down-regulate PPARG expression and curtail adipogenesis. Therefore, a post-translational response to control PPARG gene expression in SAT could be a counteregulatory mechanism to restrain adipogenesis. The OVE cows had greater expression of the insulin sensitivity-related genes IRS1, SLC2A4, INSR, SCD, INSIG1, DGAT2, and ADIPOQ in SAT. In skeletal muscle, where PPARA and its targets orchestrate

  18. Insulin Sensitivity in Adipose and Skeletal Muscle Tissue of Dairy Cows in Response to Dietary Energy Level and 2,4-Thiazolidinedione (TZD)

    PubMed Central

    Hosseini, Afshin; Tariq, Muhammad Rizwan; Trindade da Rosa, Fernanda; Kesser, Julia; Iqbal, Zeeshan; Mora, Ofelia; Sauerwein, Helga; Drackley, James K.; Trevisi, Erminio; Loor, Juan J.

    2015-01-01

    The effects of dietary energy level and 2,4-thiazolidinedione (TZD) injection on feed intake, body fatness, blood biomarkers and TZD concentrations, genes related to insulin sensitivity in adipose tissue (AT) and skeletal muscle, and peroxisome proliferator-activated receptor gamma (PPARG) protein in subcutaneous AT (SAT) were evaluated in Holstein cows. Fourteen nonpregnant nonlactating cows were fed a control low-energy (CON, 1.30 Mcal/kg) diet to meet 100% of estimated nutrient requirements for 3 weeks, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg) and half of the cows continued on CON for 6 weeks. All cows received an intravenous injection of TZD starting 2 weeks after initiation of dietary treatments and for an additional 2 weeks, which served as the washout period. Cows fed OVE had greater energy intake and body mass than CON, and TZD had no effect during the administration period. The OVE cows had greater TZD clearance rate than CON cows. The lower concentration of nonesterified fatty acids (NEFA) and greater concentration of insulin in blood of OVE cows before TZD injection indicated positive energy balance and higher insulin sensitivity. Administration of TZD increased blood concentrations of glucose, insulin, and beta-hydroxybutyrate (BHBA) at 2 to 4 weeks after diet initiation, while the concentration of NEFA and adiponectin (ADIPOQ) remained unchanged during TZD. The TZD upregulated the mRNA expression of PPARG and its targets FASN and SREBF1 in SAT, but also SUMO1 and UBC9 which encode sumoylation proteins known to down-regulate PPARG expression and curtail adipogenesis. Therefore, a post-translational response to control PPARG gene expression in SAT could be a counteregulatory mechanism to restrain adipogenesis. The OVE cows had greater expression of the insulin sensitivity-related genes IRS1, SLC2A4, INSR, SCD, INSIG1, DGAT2, and ADIPOQ in SAT. In skeletal muscle, where PPARA and its targets orchestrate

  19. Chronic acceleration and brain density

    NASA Technical Reports Server (NTRS)

    Hoffman, L. F.; Smith, A. H.

    1982-01-01

    Tests carried out on rabbits show that the effect of chronic acceleration is not uniform among the various tissues studied. Although body mass is reduced by the treatment, as expected, no change is apparent in brain mass or in the density of cerebrospinal fluid. Acceleration-induced changes are encountered in tissue density, the myocardium exhibiting a transient increase followed by an exponential decrease toward a limit and the brain showing an arithmetic increase in density with continued exposure to 2.5 G. The data are seen as suggesting that a specific brain load is not a regulated phenomenon and that no physiological processes occur to attenuate the increased load imposed by the hyperdynamic environment. An equation is derived indicating that the stimulus potential per unit of brain load increases with body size, even though brain density decreases and cerebrospinal fluid density increases.

  20. Detecting Density Variations and Nanovoids

    SciTech Connect

    Miller, Michael K; Longstreth-Spoor, L.; Kelton, K. F.

    2011-01-01

    A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1 nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field ion microscopy and thin section atom maps have also been used to detect pores and larger voids.

  1. Attractor comparisons based on density

    SciTech Connect

    Carroll, T. L.

    2015-01-15

    Recognizing a chaotic attractor can be seen as a problem in pattern recognition. Some feature vector must be extracted from the attractor and used to compare to other attractors. The field of machine learning has many methods for extracting feature vectors, including clustering methods, decision trees, support vector machines, and many others. In this work, feature vectors are created by representing the attractor as a density in phase space and creating polynomials based on this density. Density is useful in itself because it is a one dimensional function of phase space position, but representing an attractor as a density is also a way to reduce the size of a large data set before analyzing it with graph theory methods, which can be computationally intensive. The density computation in this paper is also fast to execute. In this paper, as a demonstration of the usefulness of density, the density is used directly to construct phase space polynomials for comparing attractors. Comparisons between attractors could be useful for tracking changes in an experiment when the underlying equations are too complicated for vector field modeling.

  2. Maps of current density using density-functional methods

    NASA Astrophysics Data System (ADS)

    Soncini, A.; Teale, A. M.; Helgaker, T.; de Proft, F.; Tozer, D. J.

    2008-08-01

    The performance of several density-functional theory (DFT) methods for the calculation of current densities induced by a uniform magnetic field is examined. Calculations are performed using the BLYP and KT3 generalized-gradient approximations, together with the B3LYP hybrid functional. For the latter, both conventional and optimized effective potential (OEP) approaches are used. Results are also determined from coupled-cluster singles-and-doubles (CCSD) electron densities by a DFT constrained search procedure using the approach of Wu and Yang (WY). The current densities are calculated within the CTOCD-DZ2 distributed origin approach. Comparisons are made with results from Hartree-Fock (HF) theory. Several small molecules for which correlation is known to be especially important in the calculation of magnetic response properties are considered-namely, O3, CO, PN, and H2CO. As examples of aromatic and antiaromatic systems, benzene and planarized cyclooctatetraene molecules are considered, with specific attention paid to the ring current phenomenon and its Kohn-Sham orbital origin. Finally, the o-benzyne molecule is considered as a computationally challenging case. The HF and DFT induced current maps show qualitative differences, while among the DFT methods the maps show a similar qualitative structure. To assess quantitative differences in the calculated current densities with different methods, the maximal moduli of the induced current densities are compared and integration of the current densities to yield shielding constants is performed. In general, the maximal modulus is reduced in moving from HF to B3LYP and BLYP, and further reduced in moving to KT3, OEP(B3LYP), and WY(CCSD). The latter three methods offer the most accurate shielding constants in comparison with both experimental and ab initio data and hence the more reliable route to DFT calculation of induced current density in molecules.

  3. Volcanogenic Massive Sulfide Deposit Density

    USGS Publications Warehouse

    Mosier, Dan L.; Singer, Donald A.; Berger, Vladimir I.

    2007-01-01

    A mineral-deposit density model for volcanogenic massive sulfide deposits was constructed from 38 well-explored control areas from around the world. Control areas contain at least one exposed volcanogenic massive sulfide deposit. The control areas used in this study contain 150 kuroko, 14 Urals, and 25 Cyprus massive sulfide subtypes of volcanogenic massive sulfide deposits. For each control area, extent of permissive rock, number of exposed volcanogenic massive sulfide deposits, map scale, deposit age, and deposit density were determined. The frequency distribution of deposit densities in these 38 control areas provides probabilistic estimates of the number of deposits for tracts that are permissive for volcanogenic massive sulfide deposits-90 percent of the control areas have densities of 100 or more deposits per 100,000 square kilometers, 50 percent of the control areas have densities of 700 or more deposits per 100,000 square kilometers, and 10 percent of the control areas have densities of 3,700 or more deposits per 100,000 square kilometers. Both map scale and the size of the control area are shown to be predictors of deposit density. Probabilistic estimates of the number of volcanogenic massive sulfide deposits can be made by conditioning the estimates on sizes of permissive area. The model constructed for this study provides a powerful tool for estimating the number of undiscovered volcanogenic massive sulfide deposits when conducting resource assessments. The value of these deposit densities is due to the consistency of these models with the grade and tonnage and the descriptive models. Mineral-deposit density models combined with grade and tonnage models allow reasonable estimates of the number, size, and grades of volcanogenic massive sulfide deposits to be made.

  4. Density of very small meteoroids

    NASA Astrophysics Data System (ADS)

    Kikwaya Eluo, Jean-Baptiste

    2015-08-01

    Knowing the density of meteoroids helps to determine the physical structure and gives insight into the composition of their parent bodies. The density of meteoroids can provide clues to their origins, whether cometary or asteroidal. Density helps also to characterize the risk meteoroids may pose to artificial satellites.Ceplecha (1968) calculated the density of small meteoroids based on a parameter KB (meteoroid beginning height) and classified them in four categories (A,B,C,D) with densities going from 2700 to 180 kgm-3.Babadzhanov(2002) applied a model based on quasi-continuous fragmentation (QCF) on 413 photographic Super-Schmidt meteors by solely fitting their light curves. Their densities range from 400 to 7800 kgm-3. Bellot Rubio et al. (2002) analyzed the same 413 photographic meteors assuming the single body theory based on meteoroid dynamical properties and found densities ranging from 400 to 4800 kgm-3. A thermal erosion model was used by Borovicka et al. (2007) to analyze, simultaneously, the observed decelerations and light curves of six Draconid meteors. The density was found to be 300 kgm-3, consistent with the fact that the Draconid meteors are porous aggregates of grains associated with the Jupiter-family-comet 21P/Giacobini-Zinner (Jacchia, L.G., 1950).We used the Campbell-Brown and Koschny (2004) model of meteoroid ablation to determine the density of faint meteoroids from the analysis of both observed decelerations and light curves of meteoroids (Kikwaya et al., 2009; Kikwaya et al., 2011). Our work was based on a collection of six and ninety-two sporadic meteors. The grain masses used in the modeling ranged from 10-12 Kg to 10-9 Kg. We computed the orbit of each meteoroid and determined its Tisserand parameter. We found that meteoroids with asteroidal orbits have bulk densities ranging from 3000-5000 kgm-3. Meteoroids consistent with HTC/NIC parents have bulk densities from 400 kgm-3 to 1600 kg m-3. JFC meteoroids were found to have surprisingly

  5. Density in a Planetary Exosphere

    NASA Technical Reports Server (NTRS)

    Herring, Jackson; Kyle, Herbert L.

    1961-01-01

    A discussion of the Opik-Singer theory of the density of a planetary exosphere is presented. Their density formula permits the calculation of the depth of the exosphere. Since the correctness of their derivation of the basic formula for the density distribution has been questioned, an alternate method based directly on Liouville's theorem is given. It is concluded that the Opik-Singer formula seems valid for the ballistic component of the exosphere; but for a complete description of the planetary exosphere, the ionized and bound-orbit components must also be included.

  6. Fragmentation and densities of meteoroids

    NASA Technical Reports Server (NTRS)

    Babadzhanov, Pulat B.

    1992-01-01

    Photographic observations of meteors carried out in Dushanbe by the method of instantaneous exposure have shown clearly that meteoroids entering the Earth's atmosphere are subjected to different types of fragmentation. The quasi-continuous fragmentation of meteoroids is mostly widespread. Using the physical theory of meteors which takes into account the quasi-continuous fragmentation of meteoroids and on the basis of light curves of meteors the densities of meteoroids of different streams have been determined. The results enable us to conclude that the densities of meteoroids are over an order of magnitude higher than they have been assumed before. Moreover they are close to the densities of carbonaceous and ordinary chondrites.

  7. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  8. Densely-packed ZnTPPs Monolayer on the Rutile TiO2(110)-(1×1) Surface: Adsorption Behavior and Energy Level Alignment

    PubMed Central

    Rangan, Sylvie; Ruggieri, Charles; Bartynski, Robert; Martínez, José Ignacio; Flores, Fernando; Ortega, José

    2016-01-01

    The adsorption of a densely packed Zinc(II) tetraphenylporphyrin monolayer on a rutile TiO2(110)-(1×1) surface has been studied using a combination of experimental and theoretical methods, aimed at analyzing the relation between adsorption behavior and barrier height formation. The adsorption configuration of ZnTPP was determined from scanning tunnel microscopy (STM) imaging, density functional theory (DFT) calculations and STM image simulation. The corresponding energy alignment was experimentally determined from X-ray and UV-photoemission spectroscopies and inverse photoemission spectroscopy. These results were found in good agreement with an appropriately corrected DFT model, pointing to the importance of local bonding and intermolecular interactions in the establishment of barrier heights. PMID:26998188

  9. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  10. Floquet topological systems in the vicinity of level crossings: Reservoir induced coherence of the Floquet density matrix and steady-state entropy production

    NASA Astrophysics Data System (ADS)

    Dehghani, Hossein; Mitra, Aditi

    Results are presented for a Floquet topological system for the case where the separation between quasi-energy levels becomes small, and in particular, comparable to the coupling strength to an external reservoir. For this case, even at steady-state, the reduced density matrix in the Floquet basis has non-zero off-diagonal elements, with the strength of the off-diagonal elements increasing as one approaches the level crossings. The steady-state reduced density matrix has oscillations at integer multiples of the periodic drive, and a Fourier decomposition allows the extraction of the occupation of the Floquet quasi-energy levels, which also depends on the coupling to the reservoir. The lack of detailed balance is quantified in terms of an entropy production rate. Supported by US Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0010821.

  11. Density and pair-density scaling for deriving the Euler equation in density-functional and pair-density-functional theory

    SciTech Connect

    Nagy, A.

    2011-09-15

    A link between density and pair density functional theories is presented. Density and pair density scaling are used to derive the Euler equation in both theories. Density scaling provides a constructive way of obtaining approximations for the Pauli potential. The Pauli potential (energy) of the density functional theory is expressed as the difference of the scaled and original exchange-correlation potentials (energies).

  12. The effect of ligand substitution and water co-adsorption on the adsorption dynamics and energy level matching of amino-phenyl acid dyes on TiO2.

    PubMed

    Manzhos, Sergei; Segawa, Hiroshi; Yamashita, Koichi

    2012-02-01

    We perform a comparative theoretical analysis of adsorption of dyes NK1 (2E,4E-2-cyano-5-(4-dimethylaminophenyl)penta-2,4-dienoic acid) and NK7 (2E,4E-2-cyano-5-(4-diphenylaminophenyl)penta-2,4-dienoic acid) on clean and water-covered anatase (101) surfaces of TiO(2). Ligand substitution away from the anchoring group changes the energy level matching between the dye's LUMO and the oxide's conduction band. Monodentate binding and bidentate binding configurations of the dyes to TiO(2) are found to have similar adsorption energies even though the injection from the bidentate mode is found to dominate. Water has a strong effect on adsorption, inducing deprotonation and affecting strongly and differently between the dyes the energy level matching, leading to a shut-off of the injection from NK7 of bidentate adsorption configuration. Ab initio molecular dynamics simulations show a strong effect of nuclear motion on energy levels, specifically, increasing the driving force for injection in the monodentate regime.

  13. Low density metal hydride foams

    DOEpatents

    Maienschein, Jon L.; Barry, Patrick E.

    1991-01-01

    Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.

  14. Density waves in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.; Lissauer, J. J.; Shu, F. H.

    1981-08-01

    Certain radial brightness variations in the outer Cassini division of Saturn's rings may be spiral density waves driven by Saturn's large moon Iapetus, in which case a value of approximately 16 g/sq cm for the surface density is calculated in the region where the waves are seen. The kinematic viscosity in the same region is approximately 170 sq cm/s and the vertical scale height of the ring is estimated to be a maximum of approximately 40 m.

  15. General performance of density functionals.

    PubMed

    Sousa, Sérgio Filipe; Fernandes, Pedro Alexandrino; Ramos, Maria João

    2007-10-25

    The density functional theory (DFT) foundations date from the 1920s with the work of Thomas and Fermi, but it was after the work of Hohenberg, Kohn, and Sham in the 1960s, and particularly with the appearance of the B3LYP functional in the early 1990s, that the widespread application of DFT has become a reality. DFT is less computationally demanding than other computational methods with a similar accuracy, being able to include electron correlation in the calculations at a fraction of time of post-Hartree-Fock methodologies. In this review we provide a brief outline of the density functional theory and of the historic development of the field, focusing later on the several types of density functionals currently available, and finishing with a detailed analysis of the performance of DFT across a wide range of chemical properties and system types, reviewed from the most recent benchmarking studies, which encompass several well-established density functionals together with the most recent efforts in the field. Globally, an overall picture of the level of performance of the plethora of currently available density functionals for each chemical property is drawn, with particular attention being dedicated to the relative performance of the popular B3LYP density functional.

  16. A summary of transition probabilities for atomic absorption lines formed in low-density clouds

    NASA Technical Reports Server (NTRS)

    Morton, D. C.; Smith, W. H.

    1973-01-01

    A table of wavelengths, statistical weights, and excitation energies is given for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV. Oscillator strengths were adopted for 635 lines in 155 multiplets from the available experimental and theoretical determinations. Radiation damping constants also were derived for most of these lines. This table contains the lines most likely to be observed in absorption in interstellar clouds, circumstellar shells, and the clouds in the direction of quasars where neither the particle density nor the radiation density is high enough to populate the higher levels. All ions of all elements from hydrogen to zinc are included which have resonance lines longward of 912 A, although a number of weaker lines of neutrals and first ions have been omitted.

  17. Density Distributions of Cyclotrimethylenetrinitramines (RDX)

    SciTech Connect

    Hoffman, D M

    2002-03-19

    As part of the US Army Foreign Comparative Testing (FCT) program the density distributions of six samples of class 1 RDX were measured using the density gradient technique. This technique was used in an attempt to distinguish between RDX crystallized by a French manufacturer (designated insensitive or IRDX) from RDX manufactured at Holston Army Ammunition Plant (HAAP), the current source of RDX for Department of Defense (DoD). Two samples from different lots of French IRDX had an average density of 1.7958 {+-} 0.0008 g/cc. The theoretical density of a perfect RDX crystal is 1.806 g/cc. This yields 99.43% of the theoretical maximum density (TMD). For two HAAP RDX lots the average density was 1.786 {+-} 0.002 g/cc, only 98.89% TMD. Several other techniques were used for preliminary characterization of one lot of French IRDX and two lot of HAAP RDX. Light scattering, SEM and polarized optical microscopy (POM) showed that SNPE and Holston RDX had the appropriate particle size distribution for Class 1 RDX. High performance liquid chromatography showed quantities of HMX in HAAP RDX. French IRDX also showed a 1.1 C higher melting point compared to HAAP RDX in the differential scanning calorimetry (DSC) consistent with no melting point depression due to the HMX contaminant. A second part of the program involved characterization of Holston RDX recrystallized using the French process. After reprocessing the average density of the Holston RDX was increased to 1.7907 g/cc. Apparently HMX in RDX can act as a nucleating agent in the French RDX recrystallization process. The French IRDX contained no HMX, which is assumed to account for its higher density and narrower density distribution. Reprocessing of RDX from Holston improved the average density compared to the original Holston RDX, but the resulting HIRDX was not as dense as the original French IRDX. Recrystallized Holston IRDX crystals were much larger (3-500 {micro}m or more) then either the original class 1 HAAP RDX or

  18. Imaginary time density-density correlations for two-dimensional electron gases at high density

    SciTech Connect

    Motta, M.; Galli, D. E.; Moroni, S.; Vitali, E.

    2015-10-28

    We evaluate imaginary time density-density correlation functions for two-dimensional homogeneous electron gases of up to 42 particles in the continuum using the phaseless auxiliary field quantum Monte Carlo method. We use periodic boundary conditions and up to 300 plane waves as basis set elements. We show that such methodology, once equipped with suitable numerical stabilization techniques necessary to deal with exponentials, products, and inversions of large matrices, gives access to the calculation of imaginary time correlation functions for medium-sized systems. We discuss the numerical stabilization techniques and the computational complexity of the methodology and we present the limitations related to the size of the systems on a quantitative basis. We perform the inverse Laplace transform of the obtained density-density correlation functions, assessing the ability of the phaseless auxiliary field quantum Monte Carlo method to evaluate dynamical properties of medium-sized homogeneous fermion systems.

  19. Effects of Prepartum Dietary Energy Level and Nicotinic Acid Supplementation on Immunological, Hematological and Biochemical Parameters of Periparturient Dairy Cows Differing in Parity

    PubMed Central

    Tienken, Reka; Kersten, Susanne; Frahm, Jana; Hüther, Liane; Meyer, Ulrich; Huber, Korinna; Rehage, Jürgen; Dänicke, Sven

    2015-01-01

    Simple Summary Several biological changes occur during the transition from late pregnancy to early lactation which is associated with a high susceptibility of health disorders. Nicotinic acid, as feed additive, is suggested to balance catabolic metabolism of periparturient dairy cows by attenuating lipolysis and impact production performance. This study provides information of the biological changes occurring around parturition with special emphasis on differences between primiparous and multiparous cows. Present results showed that energy-dense feeding prepartum did not result in metabolic imbalances postpartum in dairy cows which were similar in body condition score. Nicotinic acid supplementation did not reveal any effect. Abstract The periparturient period is critical according to health, productivity and profitability. As this period is fundamental for the success of the lactation period, the interest in improving periparturient health by dietary supplements increased in recent years. The present study investigated the effects of feeding nicotinic acid (NA) combined with varying dietary energy densities on immunological, hematological and biochemical parameters of periparturient cows differing in parity. Thirty-six multiparous and 20 primiparous dairy cows were enrolled in the study 42 days before expected parturition date until 100 days postpartum with the half of the cows being supplemented with 24 g of NA/d. After parturition a diet with 30% concentrate was fed to all cows which was followed by different concentrate escalation strategies. Dietary NA supplementation was ceased on day 24 postpartum. Dietary NA increased (P = 0.010) serum nicotinamide concentrations (mean of 3.35 ± 1.65 µg/mL), whereas NA could not be detected. Present data emphasize that periparturient cows are faced with major physiological challenges and that both parity-groups have different prerequisites to adapt to those changes irrespective of NA supplementation. The overfeeding of

  20. Density Measurements of Be Shells

    SciTech Connect

    Cook, R C

    2005-02-15

    The purpose of this memo is to lay out the uncertainties associated with the measurement of density of Be ablators by the weigh and volume method. I am counting on the readers to point out any faulty assumptions about the techniques or uncertainties associated with them. Based on the analysis presented below we should expect that 30 {micro}m thick shells will have an uncertainty in the measured density of about 2% of the value, coming more or less equally from the mass and volume measurement. The uncertainty is roughly inversely proportional to the coating thickness, thus a 60 {micro}m walled shell would result in a 1% uncertainty in the density.

  1. Union Density and Hospital Outcomes.

    PubMed

    Koys, Daniel J; Martin, Wm Marty; LaVan, Helen; Katz, Marsha

    2015-01-01

    The authors address the hospital outcomes of patient satisfaction, healthcare quality, and net income per bed. They define union density as the percentage of a hospital's employees who are in unions, healthcare quality as its 30-day acute myocardial infraction (AMI; heart attack) mortality rate, and patient satisfaction as its overall Hospital Consumer Assessment of Healthcare Providers and Systems score. Using a random sample of 84 union and 84 nonunion hospitals from across the United States, multiple regression analyses show that union density is negatively related to patient satisfaction. Union density is not related to healthcare quality as measured by the AMI mortality rate or to net income per bed. This implies that unions per se are not good or bad for hospitals. The authors suggest that it is better for hospital administrators to take a Balanced Scorecard approach and be concerned about employee satisfaction, patient satisfaction, healthcare quality, and net income. PMID:26652043

  2. Photoionization and High Density Gas

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  3. Information Density and Syntactic Repetition

    ERIC Educational Resources Information Center

    Temperley, David; Gildea, Daniel

    2015-01-01

    In noun phrase (NP) coordinate constructions (e.g., NP and NP), there is a strong tendency for the syntactic structure of the second conjunct to match that of the first; the second conjunct in such constructions is therefore low in syntactic information. The theory of uniform information density predicts that low-information syntactic…

  4. Density of Primitive Pythagorean Triples

    ERIC Educational Resources Information Center

    Killen, Duncan A.

    2004-01-01

    Based on the properties of a Primitive Pythagorean Triple (PPT), a computer program was written to generate, print, and count all PPTs greater than or equal to I[subscript x], where I[subscript x] is an arbitrarily chosen integer. The Density of Primitive Pythagorean Triples may be defined as the ratio of the number of PPTs whose hypotenuse is…

  5. The Maximum Density of Water.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1985-01-01

    Discusses a series of experiments performed by Thomas Hope in 1805 which show the temperature at which water has its maximum density. Early data cast into a modern form as well as guidelines and recent data collected from the author provide background for duplicating Hope's experiments in the classroom. (JN)

  6. The Classroom: Size versus Density.

    ERIC Educational Resources Information Center

    Tanner, C. Kenneth

    2000-01-01

    Classroom density may be a more important planning consideration than size. The lower middle range for human social distance is 7 feet--not met in most classrooms containing 20 to 25 students. Students need ample space, since crowding causes behavior problems and increased maintenance costs. (Contains 10 references.) (MLH)

  7. Densities of Galcatic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark

    2015-01-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3, this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  8. Densities of Galactic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark R.

    2015-04-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3 N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3 , this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  9. Plasma digital density determining device

    DOEpatents

    Sprott, Julien C.; Lovell, Thomas W.; Holly, Donald J.

    1976-01-01

    The density of a decaying plasma in an electrically conducting enclosure is determined by applying an excitation to the cavity formed by the enclosure and counting digitally the number of resonant frequencies traversed by the combination of the cavity and the decaying plasma.

  10. Quarkonium at nonzero isospin density

    SciTech Connect

    Detmold, William; Meinel, Stefan; Shi, Zhifeng

    2013-05-01

    We calculate the energies of quarkonium bound states in the presence of a medium of nonzero isospin density using lattice QCD. The medium, created using a canonical (fixed isospin charge) approach, induces a reduction of the quarkonium energies. As the isospin density increases, the energy shifts first increase and then saturate. The saturation occurs at an isospin density close to that where previously a qualitative change in the behavior of the energy density of the medium has been observed, which was conjectured to correspond to a transition from a pion gas to a Bose-Einstein condensed phase. The reduction of the quarkonium energies becomes more pronounced as the heavy-quark mass is decreased, similar to the behavior seen in two-color QCD at nonzero quark chemical potential. In the process of our analysis, the η{sub b-π} and Υ-π scattering phase shifts are determined at low momentum. An interpolation of the scattering lengths to the physical pion mass gives a{sub η{sub b},π}=0.0025(8)(6)fm and a{sub Υ,π}=0.0030(9)(7)fm.

  11. Densities of aqueous blended amines

    SciTech Connect

    Hsu, C.H.; Li, M.H.

    1997-05-01

    Solutions of alkanolamines are an industrially important class of compounds used in the natural gas and synthetic ammonia industries and petroleum chemical plants for the removal of CO{sub 2} and H{sub 2}S from gas streams. The densities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water, DEA + 2-amino-2-methyl-1-propanol (AMP) + water, and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) + water were measured from 30 C to 80 C. A Redlich-Kister equation of the excess volume was applied to represent the density. Based on the available density data for five ternary systems: MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. The density calculations show quite satisfactory results. The overall average absolute percent deviation is about 0.04% for a total of 686 data points.

  12. LDX and the Density Pinch

    NASA Astrophysics Data System (ADS)

    Kesner, J.; Michael, P.; Woskov, P.; Davis, M.; Garnier, D.; Mauel, M.

    2010-11-01

    We observe in LDX a strong, turbulence driven densityootnotetextA. Boxer et al., Nature-Physics 6 (2010) 207. and the resulting stationary density profile. A turbulent pinch is predicted by both MHD and kinetic theory. A turbulent pinch is also observed in tokamaksootnotetextD. Baker, M. Rosenbluth, PoP 5 (1998) 2936., but the effect is particularly strong in a dipole because the magnetic field falls strongly (B1/R^3), there is no rotational transform (and therefore no ``passing'' particles) and the turbulent modes are interchange-like. As a result, whereas for a tokamak the stationary density tends to fall as ˜1/q (i.e. a factor ˜3), in LDX the peak can rise a factor of ˜30 above the edge density. The stationary profiles are robust, as seen in experiments with a modulation of the heating power or of the edge fueling. Low frequency fluctuations are observed, both at the outer plasma edge and as core chordal measurements. Quasi-coherent fluctuations are also observed under the condition of low gas feed and in this circumstance the density can diverge from the stationary profile.

  13. Statistical density modification using local pattern matching

    DOEpatents

    Terwilliger, Thomas C.

    2007-01-23

    A computer implemented method modifies an experimental electron density map. A set of selected known experimental and model electron density maps is provided and standard templates of electron density are created from the selected experimental and model electron density maps by clustering and averaging values of electron density in a spherical region about each point in a grid that defines each selected known experimental and model electron density maps. Histograms are also created from the selected experimental and model electron density maps that relate the value of electron density at the center of each of the spherical regions to a correlation coefficient of a density surrounding each corresponding grid point in each one of the standard templates. The standard templates and the histograms are applied to grid points on the experimental electron density map to form new estimates of electron density at each grid point in the experimental electron density map.

  14. Spatial Symmetries of the Local Densities

    SciTech Connect

    Rohozinski, S.; Dobaczewski, J.; Nazarewicz, Witold

    2010-01-01

    Spatial symmetries of the densities appearing in the nuclear Density Functional Theory are discussed. General forms of the local densities are derived by using methods of construction of isotropic tensor fields. The spherical and axial cases are considered.

  15. Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system

    SciTech Connect

    Yun, Dong-Jin Chung, JaeGwan; Kim, Yongsu; Park, Sung-Hoon; Kim, Seong-Heon; Heo, Sung

    2014-10-21

    Through the installation of electron gun and photon detector, an in-situ photoemission and damage-free sputtering integrated analysis system is completely constructed. Therefore, this system enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on Ultraviolet Photoemission Spectroscopy (UPS), Inverse Photoemission Spectroscopy (IPES), and reflective electron energy loss spectroscopy, the occupied/unoccupied state of in-situ deposited Tris[4-(carbazol-9-yl)phenyl]amine (TCTA) organic semiconductors on Au (E{sub LUMO}: 2.51 eV and E{sub HOMO}: 1.35 eV) and Ti (E{sub LUMO}: 2.19 eV and E{sub HOMO}: 1.69 eV) electrodes are investigated, and the variation of energy level alignments according to work function of electrode (Au: 4.81 eV and Ti: 4.19 eV) is clearly verified. Subsequently, under the same analysis condition, the unoccupied/occupied states at bulk region of TCTA/Au structures are characterized using different Ar gas cluster ion beam (Ar GCIB) and Ar ion sputtering processes, respectively. While the Ar ion sputtering process critically distorts both occupied and unoccupied states in UPS/IPES spectra, the Ar GCIB sputtering process does not give rise to damage on them. Therefore, we clearly confirm that the in-situ photoemission spectroscopy in combination with Ar GCIB sputtering allows of investigating accurate energy level alignments at bulk/interface region as well as surface region of organic semiconductor/electrode structure.

  16. Dual Cryogenic Capacitive Density Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  17. Understanding density functional theory (DFT) and completing it in practice

    SciTech Connect

    Bagayoko, Diola

    2014-12-15

    We review some salient points in the derivation of density functional theory (DFT) and of the local density approximation (LDA) of it. We then articulate an understanding of DFT and LDA that seems to be ignored in the literature. We note the well-established failures of many DFT and LDA calculations to reproduce the measured energy gaps of finite systems and band gaps of semiconductors and insulators. We then illustrate significant differences between the results from self consistent calculations using single trial basis sets and those from computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Unlike the former, the latter calculations verifiably attain the absolute minima of the occupied energies, as required by DFT. These minima are one of the reasons for the agreement between their results and corresponding, experimental ones for the band gap and a host of other properties. Further, we note predictions of DFT BZW-EF calculations that have been confirmed by experiment. Our subsequent description of the BZW-EF method ends with the application of the Rayleigh theorem in the selection, among the several calculations the method requires, of the one whose results have a full, physics content ascribed to DFT. This application of the Rayleigh theorem adds to or completes DFT, in practice, to preserve the physical content of unoccupied, low energy levels. Discussions, including implications of the method, and a short conclusion follow the description of the method. The successive augmentation of the basis set in the BZW-EF method, needed for the application of the Rayleigh theorem, is also necessary in the search for the absolute minima of the occupied energies, in practice.

  18. Effect of dry period dietary energy level in dairy cattle on volume, concentrations of immunoglobulin G, insulin, and fatty acid composition of colostrum.

    PubMed

    Mann, S; Leal Yepes, F A; Overton, T R; Lock, A L; Lamb, S V; Wakshlag, J J; Nydam, D V

    2016-02-01

    The objective was to investigate the effect of different dry cow feeding strategies on the volume, concentration of IgG and insulin, as well as fatty acid composition of colostrum. Our hypothesis was that different dry period diets formulated to resemble current feeding practices on commercial dairy farms and differing in plane of energy would have an effect on IgG and insulin concentration, as well as composition of fatty acid of colostrum. Animals (n=84) entering parity 2 or greater were dried off 57 d before expected parturition and fed either a diet formulated to meet, but not greatly exceed energy requirements throughout the dry period (CON), or a higher energy density diet, supplying approximately 150% of energy requirements (HI). A third group received the same diet as group CON from dry-off until 29 d before expected parturition. After this time point, from 28 d before expected parturition until calving, they received a diet formulated to supply approximately 125% of energy requirements (I-med). Concentration of IgG and insulin in colostrum were measured by radial immunodiffusion and RIA, respectively. Composition of fatty acids was determined by gas-liquid chromatography. The IgG concentration was highest in colostrum of cows in group CON [96.1 (95% CI: 83.3-108.9) g/L] and lowest in group HI [72.4 (60.3-84.5) g/L], whereas insulin concentration was highest in group HI [1,105 (960-1,250) μU/mL] and lowest in group CON [853 (700-1,007) μU/mL]. Colostrum yield did not differ between treatments and was 5.9 (4.5-7.4), 7.0 (5.6-8.4), and 7.3 (5.9-8.7) kg in groups CON, I-med, and HI, respectively. A multivariable linear regression model showed the effect of dietary treatment group on IgG concentration was independent of the effect of dry matter. Cows in groups CON, I-med, and HI had an average colostral fat percentage of 5.0 (4.1-5.9), 5.6 (4.8-6.4), and 6.0 (5.2-6.8) and an average fat yield of 289 (196-380), 406 (318-495), and 384 (295-473) g, respectively

  19. N-acyldithieno[3,2-b:2',3'-d]pyrroles: second generation dithieno[3,2-b:2',3'-d]pyrrole building blocks with stabilized energy levels.

    PubMed

    Evenson, Sean J; Rasmussen, Seth C

    2010-09-17

    A new class of dithieno[3,2-b:2',3'-d]pyrroles (DTPs) incorporating N-acyl groups have been prepared from 3-bromothiophene via copper-catalyzed amidation. The utilization of various electron-withdrawing acyl groups has allowed stabilization of the HOMO and LUMO energy levels of these popular building blocks for conjugated materials. The synthesis and characterization of this new class of compounds is described, including electrochemical and photophysical data for all compounds and X-ray structural data for the octanoyl, benzoyl, and cyclohexanoyl functionalized compounds. Initial polymers generated via electropolymerization are also reported.

  20. Compressed liquid densities and saturation densities of chlorodifluoromethane (R22)

    SciTech Connect

    Deflbaugh, D.R.; Morrison, G. )

    1992-01-01

    Density measurements for liquid chlorodifluoromethane (R22) were made with a vibrating-tube densimeter. The data range from 0.444 to 1.334 g/cm{sup 3} along 13 isotherms between 263 and 373 K and pressures between 1000 and 6200 kPa. In this paper the accuracy of the data is estimated to be {plus minus}0.05%, except in the near-critical region.

  1. High Energy Density Laboratory Astrophysics

    SciTech Connect

    Remington, B A

    2004-11-11

    High-energy-density (HED) physics refers broadly to the study of macroscopic collections of matter under extreme conditions of temperature and density. The experimental facilities most widely used for these studies are high-power lasers and magnetic-pinch generators. The HED physics pursued on these facilities is still in its infancy, yet new regimes of experimental science are emerging. Examples from astrophysics include work relevant to planetary interiors, supernovae, astrophysical jets, and accreting compact objects (such as neutron stars and black holes). In this paper, we will review a selection of recent results in this new field of HED laboratory astrophysics and provide a brief look ahead to the coming decade.

  2. Generalized expression for polarization density

    SciTech Connect

    Wang Lu; Hahm, T. S.

    2009-06-15

    A general polarization density which consists of classical and neoclassical parts is systematically derived via modern gyrokinetics and bounce kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width and finite-Larmor-radius effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. The generalized analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  3. Asymptotic density and effective negligibility

    NASA Astrophysics Data System (ADS)

    Astor, Eric P.

    In this thesis, we join the study of asymptotic computability, a project attempting to capture the idea that an algorithm might work correctly in all but a vanishing fraction of cases. In collaboration with Hirschfeldt and Jockusch, broadening the original investigation of Jockusch and Schupp, we introduce dense computation, the weakest notion of asymptotic computability (requiring only that the correct answer is produced on a set of density 1), and effective dense computation, where every computation halts with either the correct answer or (on a set of density 0) a symbol denoting uncertainty. A few results make more precise the relationship between these notions and work already done with Jockusch and Schupp's original definitions of coarse and generic computability. For all four types of asymptotic computation, including generic computation, we demonstrate that non-trivial upper cones have measure 0, building on recent work of Hirschfeldt, Jockusch, Kuyper, and Schupp in which they establish this for coarse computation. Their result transfers to yield a minimal pair for relative coarse computation; we generalize their method and extract a similar result for relative dense computation (and thus for its corresponding reducibility). However, all of these notions of near-computation treat a set as negligible iff it has asymptotic density 0. Noting that this definition is not computably invariant, this produces some failures of intuition and a break with standard expectations in computability theory. For instance, as shown by Hamkins and Miasnikov, the halting problem is (in some formulations) effectively densely computable, even in polynomial time---yet this result appears fragile, as indicated by Rybalov. In independent work, we respond to this by strengthening the approach of Jockusch and Schupp to avoid such phenomena; specifically, we introduce a new notion of intrinsic asymptotic density, invariant under computable permutation, with rich relations to both

  4. Generalized Expression for Polarization Density

    SciTech Connect

    Lu Wang and T.S. Hahm

    2009-04-23

    A general polarization density which consists of classical and neoclassical parts is system-atically derived via modern gyrokinetics and bounce-kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width (FBW) and finite-Larmor-radius (FLR) effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. Our analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  5. Stable density stratification solar pond

    NASA Technical Reports Server (NTRS)

    Lansing, F. L. (Inventor)

    1985-01-01

    A stable density-stratification solar pond for use in the collection and storage of solar thermal energy including a container having a first section characterized by an internal wall of a substantially cylindrical configuration and a second section having an internal wall of a substantially truncated conical configuration surmounting the first section in coaxial alignment therewith, the second section of said container being characterized by a base of a diameter substantially equal to the diameter of the first section and a truncated apex defining a solar energy acceptance opening is discussed. A body of immiscible liquids is disposed within the container and comprises a lower portion substantially filling the first section of the container and an upper portion substantially filling the second section of the container, said lower portion being an aqueous based liquid of a darker color than the upper portion and of a greater density. A protective cover plate is removably provided for covering the acceptance opening.

  6. Variable density compressed image sampling.

    PubMed

    Wang, Zhongmin; Arce, Gonzalo R

    2010-01-01

    Compressed sensing (CS) provides an efficient way to acquire and reconstruct natural images from a limited number of linear projection measurements leading to sub-Nyquist sampling rates. A key to the success of CS is the design of the measurement ensemble. This correspondence focuses on the design of a novel variable density sampling strategy, where the a priori information of the statistical distributions that natural images exhibit in the wavelet domain is exploited. The proposed variable density sampling has the following advantages: 1) the generation of the measurement ensemble is computationally efficient and requires less memory; 2) the necessary number of measurements for image reconstruction is reduced; 3) the proposed sampling method can be applied to several transform domains and leads to simple implementations. Extensive simulations show the effectiveness of the proposed sampling method.

  7. High energy density aluminum battery

    DOEpatents

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  8. Low-density ionization behavior

    SciTech Connect

    Baker, G.A. Jr.

    1995-04-01

    As part of a continuing study of the physics of matter under extreme conditions, I give some results on matter at extremely low density. In particular I compare a quantum mechanical calculation of the pressure for atomic hydrogen with the corresponding pressure given by Thomas-Fermi theory. (This calculation differs from the ``confined atom`` approximation in a physically significant way.) Since Thomas-Fermi theory in some sense, represents the case of infinite nuclear charge, these cases should represent extremes. Comparison is also made with Saha theory, which considers ionization from a chemical point of view, but is weak on excited-state effects. In this theory, the pressure undergoes rapid variation as electron ionization levels are passed. This effect is in contrast to the smooth behavior of the Thomas-Fermi fixed temperature, complete ionization occurs in the low density limit, I study the case where the temperature goes appropriately to zero with the density. Although considerable modification is required, Saha theory is closer to the actual results for this case than is Thomas-Fermi theory.

  9. Density functionals from deep learning

    NASA Astrophysics Data System (ADS)

    McMahon, Jeffrey

    Density-functional theory is a formally exact description of a many-body quantum system in terms of its density; in practice, however, approximations to the universal density functional (DF) are necessary. Machine learning has recently been proposed as a novel approach to discover such a DF (or components of it). Conventional machine learning algorithms, however, are limited in their ability to process data in their raw form, leading to invariance and/or sensitivity issues. In this presentation, an alternative approach based on deep learning will be demonstrated. Deep learning allows computational models that are capable of discovering intricate structure in large and/or high-dimensional data sets with multiple levels of abstraction, and do not suffer from the aforementioned issues. Results from the application of this approach to the prediction of the kinetic-energy DF of noninteracting electrons will be presented. Using theoretical results from computer science, a connection between the underlying model and the theorems of Hohenberg and Kohn will also be suggested.

  10. Spatially revolved high density electroencephalography

    NASA Astrophysics Data System (ADS)

    Wu, Jerry; Szu, Harold; Chen, Yuechen; Guo, Ran; Gu, Xixi

    2015-05-01

    Electroencephalography (EEG) measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In practice, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, several tens of minutes, as recorded from multiple electrodes placed on the scalp. In order to improve the resolution and the distortion cause by the hair and scalp, large array magnetoencephalography (MEG) systems are introduced. The major challenge is to systematically compare the accuracy of epileptic source localization with high electrode density to that obtained with sparser electrode setups. In this report, we demonstrate a two dimension (2D) image Fast Fourier Transform (FFT) analysis along with utilization of Peano (space-filling) curve to further reduce the hardware requirement for high density EEG and improve the accuracy and performance of the high density EEG analysis. The brain-computer interfaces (BCIs) in this work is enhanced by A field-programmable gate array (FPGA) board with optimized two dimension (2D) image Fast Fourier Transform (FFT) analysis.

  11. Stringy holography at finite density

    NASA Astrophysics Data System (ADS)

    Goykhman, Mikhail; Parnachev, Andrei

    2013-09-01

    We consider an exactly solvable worldsheet string theory in the background of a black brane with a gauge field flux. Holographically, such a system can be interpreted as a field theory with finite number of degrees of freedom at finite temperature and density. This is to be contrasted with more conventional holographic models which involve gravity in the bulk and possess infinite number of degrees of freedom and mean field critical exponents. We construct closed string vertex operators which holographically represent the U(1) gauge field and the stress-energy tensor and compute their two-point functions. At finite temperature and vanishing charge density the low-energy excitations are described by hydrodynamics. As the density is raised, the system behaves like a sum of two non-interacting fluids. We find low-energy excitations in the shear and sound channels of each fluid. We thank A. Giveon for pointing out to us the role of this equation in the 2d charged black hole solution of type-II superstring theory.

  12. The excited state dynamics of KLa(MoO{sub 4}){sub 2}:Pr{sup 3+}: From a case study to the determination of the energy levels of rare earth impurities relative to the bandgap in oxidising host lattices

    SciTech Connect

    Cavalli, Enrico Boutinaud, Philippe; Bettinelli, Marco; Dorenbos, Pieter

    2008-05-15

    The luminescence properties of KLa(MoO{sub 4}){sub 2} (KLM) single crystals doped with Pr{sup 3+} have been measured in the 10-600 K temperature range in order to investigate the mechanisms involved in the radiationless processes. At variance with previously studied scheelite-like molybdates activated with Pr{sup 3+}, no effects attributed to the formation of intervalence charge transfer states have been observed. The model proposed in order to account for this behaviour allows the determination of the energy of the Pr{sup 3+} levels relative to the valence and conduction bands of the host. This model has firstly been confirmed for Tb{sup 3+}-doped KLM, for which suitable experimental data are available, and then extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties. The obtained conclusions are finally supported in the light of the comparison with some other representative cases. - Graphical abstract: The study of the excited state dynamics of KLa(MoO{sub 4}){sub 2} single crystals doped with Pr{sup 3+} allows to determine the energies of the levels of the active ion relative to the valence and conduction bands of the host. This model has then been extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties.

  13. Electron Density and Capacitance at the interface of Au-ZnO Based Schottky Diode

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Sheng

    ZnO with wide direct band gap (3.37 eV) is a well-known and an interesting compound semiconducting material, which have been used for the fabrication of optical, electrical, and piezoelectric devices such as light emitting diodes, solar cells. Schottky diodes are associated with quicker switching and lower turn on voltages compared to p-n junction diodes. J-V characteristics exhibit nonlinear rectifying behavior with threshold voltage of 2.1 V. The barrier heights were found to be 0.61 eV. The measured capacitance for the Schottky junction depends on the reverse bias potential and frequency. At the lower frequencies the capacitance has the higher values due to the trapping occurred at the interface through the surface roughness and lattice mismatch. We perform model potential calculation with quantum well around the interface. Model potentials allow some degree of freedom in the design of the emitted wavelength through adjustment of the energy levels. We apply the various well width w and barrier height V in order to match the device information made by Willander. Solving the Schrödinger equation with exchange- correlation energy and effective mass of electrons will produce values of the energy levels and states. The variational barrier heights result in the change of the electron density This accounts for the excessive capacitance at the interface of Schottky diode.

  14. Probability distribution of the vacuum energy density

    SciTech Connect

    Duplancic, Goran; Stefancic, Hrvoje; Glavan, Drazen

    2010-12-15

    As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.

  15. Density estimation in wildlife surveys

    USGS Publications Warehouse

    Bart, J.; Droege, S.; Geissler, P.; Peterjohn, B.; Ralph, C.J.

    2004-01-01

    Several authors have recently discussed the problems with using index methods to estimate trends in population size. Some have expressed the view that index methods should virtually never be used. Others have responded by defending index methods and questioning whether better alternatives exist. We suggest that index methods are often a cost-effective component of valid wildlife monitoring but that double-sampling or another procedure that corrects for bias or establishes bounds on bias is essential. The common assertion that index methods require constant detection rates for trend estimation is mathematically incorrect; the requirement is no long-term trend in detection "ratios" (index result/parameter of interest), a requirement that is probably approximately met by many well-designed index surveys. We urge that more attention be given to defining bird density rigorously and in ways useful to managers. Once this is done, 4 sources of bias in density estimates may be distinguished: coverage, closure, surplus birds, and detection rates. Distance, double-observer, and removal methods do not reduce bias due to coverage, closure, or surplus birds. These methods may yield unbiased estimates of the number of birds present at the time of the survey, but only if their required assumptions are met, which we doubt occurs very often in practice. Double-sampling, in contrast, produces unbiased density estimates if the plots are randomly selected and estimates on the intensive surveys are unbiased. More work is needed, however, to determine the feasibility of double-sampling in different populations and habitats. We believe the tension that has developed over appropriate survey methods can best be resolved through increased appreciation of the mathematical aspects of indices, especially the effects of bias, and through studies in which candidate methods are evaluated against known numbers determined through intensive surveys.

  16. Analysis of trap state densities at HfO{sub 2}/In{sub 0.53}Ga{sub 0.47}As interfaces

    SciTech Connect

    Hwang, Yoontae; Engel-Herbert, Roman; Rudawski, Nicholas G.; Stemmer, Susanne

    2010-03-08

    HfO{sub 2} was deposited on n- and p-type In{sub 0.53}Ga{sub 0.47}As by chemical beam deposition. Interface trap densities (D{sub it}) and their energy level distribution were quantified using the conductance method in a wide temperature range (77 to 300 K). A trap level close to the intrinsic energy level caused the D{sub it} to rise above 10{sup 13} cm{sup -2} eV{sup -1}. The trap level at midgap gives rise to false inversion behavior in the capacitance-voltage curves for n-type channels at room temperature. The apparent decrease of the D{sub it} close to the band edges is discussed.

  17. High-density digital recording

    NASA Technical Reports Server (NTRS)

    Kalil, F. (Editor); Buschman, A. (Editor)

    1985-01-01

    The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

  18. QCD AT HIGH PARTON DENSITY

    SciTech Connect

    KOVCHEGOV,Y.V.

    2000-04-25

    The authors derive an equation determining the small-x evolution of the F{sub 2} structure function of a large nucleus which resumes a cascade of gluons in the leading logarithmic approximation using Mueller's color dipole model. In the traditional language it corresponds to resummation of the pomeron fan diagrams, originally conjectured in the GLR equation. The authors show that the solution of the equation describes the physics of structure functions at high partonic densities, thus allowing them to gain some understanding of the most interesting and challenging phenomena in small-x physics--saturation.

  19. High-Energy-Density Capacitors

    NASA Technical Reports Server (NTRS)

    Slenes, Kirk

    2003-01-01

    Capacitors capable of storing energy at high densities are being developed for use in pulse-power circuits in such diverse systems as defibrillators, particle- beam accelerators, microwave sources, and weapons. Like typical previously developed energy-storage capacitors, these capacitors are made from pairs of metal/solid-dielectric laminated sheets that are wound and pressed into compact shapes to fit into cans, which are then filled with dielectric fluids. Indeed, these capacitors can be fabricated largely by conventional fabrication techniques. The main features that distinguish these capacitors from previously developed ones are improvements in (1) the selection of laminate materials, (2) the fabrication of the laminated sheets from these materials, and (3) the selection of dielectric fluids. In simplest terms, a high-performance laminated sheet of the type used in these capacitors is made by casting a dielectric polymer onto a sheet of aluminized kraft paper. The dielectric polymer is a siloxane polymer that has been modified with polar pendant groups to increase its permittivity and dielectric strength. Potentially, this polymer is capable of withstanding an energy density of 7.5 J/cm3, which is four times that of the previous state-of-the-art-capacitor dielectric film material. However, the full potential of this polymer cannot be realized at present because (1) at thicknesses needed for optimum performance (.8.0 m), the mechanical strength of a film of this polymer is insufficient for incorporation into a wound capacitor and (2) at greater thickness, the achievable energy density decreases because of a logarithmic decrease in dielectric strength with increasing thickness. The aluminized kraft paper provides the mechanical strength needed for processing of the laminate and fabrication of the capacitor, and the aluminum film serves as an electrode layer. Because part of the thickness of the dielectric is not occupied by the modified siloxane polymer, the

  20. DENSITY CONTROL IN A REACTOR

    DOEpatents

    Marshall, J. Jr.

    1961-10-24

    A reactor is described in which natural-uranium bodies are located in parallel channels which extend through the graphite mass in a regular lattice. The graphite mass has additional channels that are out of the lattice and contain no uranium. These additional channels decrease in number per unit volume of graphite from the center of the reactor to the exterior and have the effect of reducing the density of the graphite more at the center than at the exterior, thereby spreading neutron activity throughout the reactor. (AEC)

  1. Current density distribution in PEFC

    NASA Astrophysics Data System (ADS)

    Liu, Zhixiang; Mao, Zongqiang; Wu, Bing; Wang, Lisheng; Schmidt, Volkmar M.

    The determination of the current distribution in a polymer electrolyte fuel cell (PEFC) is of great practical importance to optimize the process parameter such as the flow field design, the humidification of reaction gases and the utilization of the fuel gas. In this paper, subcells approach is used to measure current density distribution in PEFC with an active electrode area of 30 cm 2. Fuel cell performances determined under different operation conditions clearly indicate that the water balance influences the cell performance most significantly. Furthermore, it is interesting to note that under certain condition both membrane drying and electrode flooding are shown simultaneously inducing performance decaying.

  2. Crystal-field energy level analysis for Nd(3+) ions at the low symmetry C(1) site in [Nd(hfa)(4)(H(2)O)](N(C(2)H(5))(4)) single crystals.

    PubMed

    Mech, Agnieszka; Gajek, Zbigniew; Karbowiak, Mirosław; Rudowicz, Czesław

    2008-09-24

    Optical absorption measurements of Nd(3+) ions in single crystals of [Nd(hfa)(4)(H(2)O)](N(C(2)H(5))(4)) (hfa = hexafluoroacetyloacetonate), denoted Nd(hfa) for short, have been carried out at 4.2 and 298 K. This compound crystallizes in the monoclinic system (space group P 2(1)/n). Each Nd ion is coordinated to eight oxygen atoms that originate from the hexafluoroacetylacetonate ligands and one oxygen atom from the water molecule. A total of 85 experimental crystal-field (CF) energy levels arising from the Nd(3+) (4f(3)) electronic configuration were identified in the optical spectra and assigned. A three-step CF analysis was carried out in terms of a parametric Hamiltonian for the actual C(1) symmetry at the Nd(3+) ion sites. In the first step, a total of 27 CF parameters (CFPs) in the Wybourne notation B(kq), admissible by group theory, were determined in a preliminary fitting constrained by the angular overlap model predictions. The resulting CFP set was reduced to 24 specific independent CFPs using appropriate standardization transformations. Optimizations of the second-rank CFPs and extended scanning of the parameter space were employed in the second step to improve reliability of the CFP sets, which is rather a difficult task in the case of no site symmetry. Finally, seven free-ion parameters and 24 CFPs were freely varied, yielding an rms deviation between the calculated energy levels and the 85 observed ones of 11.1 cm(-1). Our approach also allows prediction of the energy levels of Nd(3+) ions that are hidden in the spectral range overlapping with strong ligand absorption, which is essential for understanding the inter-ionic energy transfer. The orientation of the axis system associated with the fitted CF parameters w.r.t. the crystallographic axes is established. The procedure adopted in our calculations may be considered as a general framework for analysis of CF levels of lanthanide ions at low (triclinic) symmetry sites.

  3. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, Ron; Cotton, Matthew; Harris, Ernest; Eakins, Daniel; Chapman, David

    2013-06-01

    Ramp loading using graded-density-impactors as flyers in plate impact experiments can yield useful information about the dynamic properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to fabricate a graded-density flyer, termed the ``bed of nails'' (BON). A 2 mm thick x 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. Two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at The Institute of Shock Physics, Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in free surface velocity over a period of about 2.5 microseconds. The measured profiles have been analysed to generate a stress vs. volume curve for tantalum.

  4. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, R. E.; Cotton, M.; Harris, E. J.; Chapman, D. J.; Eakins, D.

    2014-05-01

    Ramp loading using graded-density-impactors as flyers in gas-gun-driven plate impact experiments can yield new and useful information about the equation of state and the strength properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to manufacture a graded density flyer, termed the "bed of nails" (BON). A 2 mm thick × 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. The two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at the Institute of Shock Physics at Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, which were mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in velocity over a period of ~2.5 us, with no indication of a shock jump. The measured profiles have been analysed to generate a stress strain curve for tantalum. The results have been compared with the predictions of the Sandia National Laboratories hydrocode, CTH.

  5. Density functional theory: Foundations reviewed

    NASA Astrophysics Data System (ADS)

    Kryachko, Eugene S.; Ludeña, Eduardo V.

    2014-11-01

    Guided by the above motto (quotation), we review a broad range of issues lying at the foundations of Density Functional Theory, DFT, a theory which is currently omnipresent in our everyday computational study of atoms and molecules, solids and nano-materials, and which lies at the heart of modern many-body computational technologies. The key goal is to demonstrate that there are definitely the ways to improve DFT. We start by considering DFT in the larger context provided by reduced density matrix theory (RDMT) and natural orbital functional theory (NOFT), and examine the implications that N-representability conditions on the second-order reduced density matrix (2-RDM) have not only on RDMT and NOFT but, also, by extension, on the functionals of DFT. This examination is timely in view of the fact that necessary and sufficient N-representability conditions on the 2-RDM have recently been attained. In the second place, we review some problems appearing in the original formulation of the first Hohenberg-Kohn theorem which is still a subject of some controversy. In this vein we recall Lieb's comment on this proof and the extension to this proof given by Pino et al. (2009), and in this context examine the conditions that must be met in order that the one-to-one correspondence between ground-state densities and external potentials remains valid for finite subspaces (namely, the subspaces where all Kohn-Sham solutions are obtained in practical applications). We also consider the issue of whether the Kohn-Sham equations can be derived from basic principles or whether they are postulated. We examine this problem in relation to ab initio DFT. The possibility of postulating arbitrary Kohn-Sham-type equations, where the effective potential is by definition some arbitrary mixture of local and non-local terms, is discussed. We also deal with the issue of whether there exists a universal functional, or whether one should advocate instead the construction of problem

  6. Density shocks in confined microswimmers

    NASA Astrophysics Data System (ADS)

    Tsang, Alan Cheng Hou; Kanso, Eva; Biodynamics Team

    2014-11-01

    Motile microorganisms are often subject to different types of boundary confinement in their natural environment, but the effects of confinement on their dynamics are poorly understood. We consider an idealized model of confined microswimmers restricted to move in a two-dimensional Hele-Shaw cell. We then impose two different types of boundary confinement: circular and sidewalls confinement. We study how boundaries trigger the emergence of global modes. In the case of circular confinement, the microswimmers can spontaneously organize themselves into a single vortex state when the radius of the circular boundary is below a certain critical value, reminiscent to what have been observed in recent experiments of bacterial suspensions. In the case of sidewalls confinement in a rectangular channel, the microswimmers form density shock, via interaction with the sidewalls and background flow. We show that, through controlling the strength of background flow, we can manipulate the density shock to form at the back or front of the swimmer clusters or the suppression of the shock which gives rise to a uniform traveling wave of swimmers.

  7. Graduate density, gender, and employment.

    PubMed

    Brynin, Malcolm

    2002-09-01

    The expansion of higher education is often viewed as reflecting increased demand for skills, whether related to technological change or the growing complexity of the economy. It is also linked to widening pay differentials between the poorly and highly educated. There are reasons, however, to question these associations. Even if demand for graduates is growing the supply of graduates might as a result of the status derived from having a degree still exceed this. The demand for graduates itself need not be wholly tied in with upgrading of the labour force. Graduates could be part of a more flexible workforce who increasingly undertake non-graduate work, thus downgrading their labour-market position. LFS (Labour Force Survey) and BHPS (British Household Panel Study) data are used to show that there has been no major shift in the distribution of graduates in the British labour market, that career starts are increasingly at a lower status point, and that there is a negative effect of graduate density on wages. There are also redistributional effects. There has been a large increase in the social demand for higher education by women, and they have gained from this expansion while men have lost out. In addition, graduate density is positive for non-graduates, who gain from the reduced rewards accruing to graduates. The results call into question the simple idea of a trend towards a demand for increasing levels of skills and qualifications. More attention should be paid to the distribution of skills and to complex interactions within this.

  8. Density functional theory: Foundations reviewed

    NASA Astrophysics Data System (ADS)

    Kryachko, Eugene S.; Ludeña, Eduardo V.

    2014-11-01

    Guided by the above motto (quotation), we review a broad range of issues lying at the foundations of Density Functional Theory, DFT, a theory which is currently omnipresent in our everyday computational study of atoms and molecules, solids and nano-materials, and which lies at the heart of modern many-body computational technologies. The key goal is to demonstrate that there are definitely the ways to improve DFT. We start by considering DFT in the larger context provided by reduced density matrix theory (RDMT) and natural orbital functional theory (NOFT), and examine the implications that N-representability conditions on the second-order reduced density matrix (2-RDM) have not only on RDMT and NOFT but, also, by extension, on the functionals of DFT. This examination is timely in view of the fact that necessary and sufficient N-representability conditions on the 2-RDM have recently been attained. In the second place, we review some problems appearing in the original formulation of the first Hohenberg-Kohn theorem which is still a subject of some controversy. In this vein we recall Lieb's comment on this proof and the extension to this proof given by Pino et al. (2009), and in this context examine the conditions that must be met in order that the one-to-one correspondence between ground-state densities and external potentials remains valid for finite subspaces (namely, the subspaces where all Kohn-Sham solutions are obtained in practical applications). We also consider the issue of whether the Kohn-Sham equations can be derived from basic principles or whether they are postulated. We examine this problem in relation to ab initio DFT. The possibility of postulating arbitrary Kohn-Sham-type equations, where the effective potential is by definition some arbitrary mixture of local and non-local terms, is discussed. We also deal with the issue of whether there exists a universal functional, or whether one should advocate instead the construction of problem

  9. Energy Levels of Coupled Plasmonic Cavities

    NASA Astrophysics Data System (ADS)

    Liu, Chuan-Pu; Zhu, Xin-Li; Zhang, Jia-Sen; Xu, Jun; Leprince-Wang, Yamin; Yu, Da-Peng

    2016-08-01

    Not Available Supported by the National Basic Research Program of China under Grant No 2013CB932602, and the National Natural Science Foundation of China under Grant Nos 11574011, 61377050 and 11234001.

  10. Homolumo gap from dynamical energy levels

    SciTech Connect

    Andric, I.; Jonke, L.; Jurman, D.; Nielsen, H. B.

    2009-11-15

    We introduce a dynamical matrix model where the matrix is interpreted as a Hamiltonian representing interaction of a bosonic system with a single fermion. We show how a system of second-quantized fermions influences the ground state of the whole system by producing a gap between the highest eigenvalue of the occupied single-fermion states and the lowest eigenvalue of the unoccupied single-fermion states. We describe the development of the gap in both the strong and weak coupling regimes, while for the intermediate coupling strength we expect formation of homolumo kinks.

  11. The local dark matter density

    NASA Astrophysics Data System (ADS)

    Read, J. I.

    2014-06-01

    I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for ‘direct detection’ dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a ‘dark disc’. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data—particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I collate the latest measurements of ρdm and show that, once the baryonic surface density contribution Σb is normalized across different groups, there is remarkably good agreement. Compiling data from the literature, I estimate Σb = 54.2 ± 4.9 M⊙pc-2, where the dominant source of uncertainty is in the H i gas contribution. Assuming this contribution from the baryons, I highlight several recent measurements of ρdm in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way’s rotation curve, I show that the Milky Way is consistent with having a spherical dark matter halo at R0 ˜ 8 kpc. The very latest measures of ρdm based on ˜10 000 stars from the Sloan Digital Sky Survey appear to favour little halo flattening at R0, suggesting that the Galaxy has a rather weak dark matter disc, with a correspondingly quiescent merger history. I caution, however, that this result hinges on there being no large systematics that remain to be uncovered in the SDSS data, and on the local baryonic surface density being Σb ˜ 55 M⊙pc-2. I conclude by discussing how the new Gaia satellite will be transformative. We will obtain much tighter

  12. Electronic structure evolution and energy level alignment at C{sub 60}/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine]/MoO{sub x}/indium tin oxide interfaces

    SciTech Connect

    Liu, Xiaoliang; Yi, Shijuan; Wang, Chenggong; Wang, Congcong; Gao, Yongli

    2014-04-28

    The electronic structure evolution and energy level alignment have been investigated at interfaces comprising fullerene (C{sub 60})/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC)/ molybdenum oxide (MoO{sub x})/ indium tin oxide with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. With deposition of TAPC upon MoO{sub x}, a dipole of 1.58 eV was formed at the TAPC/MoO{sub x} interface due to electron transfer from TAPC to MoO{sub x}. The highest occupied molecular orbital (HOMO) onset of TAPC was pinned closed to the Fermi level, leading to a p-doped region and thus increasing the carrier concentration at the very interface. The downward band bending and the resulting built-in field in TAPC were favorable for the hole transfer toward the TAPC/MoO{sub x} interface. The rigid downward shift of energy levels of TAPC indicated no significant interface chemistry at the interface. With subsequent deposition of C{sub 60} on TAPC, a dipole of 0.27 eV was observed at the C{sub 60}/TAPC heterojunction due to the electron transfer from TAPC to C{sub 60}. This led to a drop of the HOMO of TAPC near the C{sub 60}/TAPC interface, and hence further enhanced the band bending in TAPC. The band bending behavior was also observed in C{sub 60}, similarly creating a built-in field in C{sub 60} film and improving the electron transfer away from the C{sub 60}/TAPC interface. It can be deduced from the interface analysis that a promising maximum open circuit voltage of 1.5 eV is achievable in C{sub 60}/TAPC-based organic photovoltaic cells.

  13. Energy levels and crystal-field parameters for Pr 3+ and Nd 3+ ions in rare earth (RE) tellurium oxides RE 2Te 4O 11 revisited - Ascent/descent in symmetry method applied for triclinic site symmetry

    NASA Astrophysics Data System (ADS)

    Karbowiak, M.; Rudowicz, C.; Gnutek, P.

    2011-06-01

    Triclinic site symmetry presents considerable challenges in the studies of energy levels and crystal-field parameters (CFPs) for rare earth (RE) ions in crystals. Assignment of the spectral features to the irreducible representations of low symmetry point groups is difficult and may be unreliable. Fittings of large number of CFPs, even if the number of the available experimental energy levels is sufficient, often yield multiple solutions with relatively low and close rms deviations. These challenges call for better methods of fitting and analysis of CFPs. In this paper, we employ the ascent/descent in symmetry (ADS) method and three computational approaches: (i) a crystallographic data analysis program to identify approximated higher symmetry, (ii) the superposition model (SPM) analysis, and (iii) the pseudosymmetry axes method (PAM) for the combined coordination factors obtained using SPM. As a case study, the experimental CF splittings of Pr 3+ and Nd 3+ ions at triclinic C 1 sites in tellurium oxides RE 2Te 4O 11 are re-analyzed. Two alternative ADS chains C 1 ↔ C 2 ↔ D 2 and C 1 ↔ C s ↔ C 2v were independently obtained. For each approximation of the actual C 1 symmetry of the REO 8 polyhedron in RE 2Te 4O 11, the ligands' positions are determined and used in SPM to calculate CFP sets, which are used as starting for additional fittings. Comparative analysis of the fitted and calculated CFP sets enables assignment of appropriate axis system to the fitted CFP sets, thus avoiding the ambiguities occurring in previous ADS applications. The very good compatibility and consistency of the newly determined CFP sets indicate high reliability of both approaches. These CFP sets were used to simulate magnetic susceptibility data for polycrystalline samples of Pr 2Te 4O 11 and Nd 2Te 4O 11. Wider applications of the proposed procedures in optical spectroscopy studies of low symmetry systems may improve reliability of the CFP sets reported in literature.

  14. LATTICE QCD AT FINITE DENSITY.

    SciTech Connect

    SCHMIDT, C.

    2006-07-23

    I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transition line as function of the chemical potential (T{sub c}({mu}{sub q})) are reviewed. Along the transition line, hadronic fluctuations have been calculated; which can be used to characterize properties of the Quark Gluon plasma and eventually can also help to identify the location of the critical end-point in the QCD phase diagram on the lattice and in heavy ion experiments. Furthermore, I comment on the structure of the phase diagram at large {mu}{sub q}.

  15. Oxides having high energy densities

    DOEpatents

    Ceder, Gerbrand; Kang, Kisuk

    2013-09-10

    Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.

  16. High density tape casting system

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor)

    1989-01-01

    A system is provided for casting thin sheets (or tapes) of particles bound together, that are used for oxygen membranes and other applications, which enables the particles to be cast at a high packing density in a tape of uniform thickness. A slurry contains the particles, a binder, and a solvent, and is cast against the inside walls of a rotating chamber. Prior to spraying the slurry against the chamber walls, a solvent is applied to a container. The solvent evaporates to saturate the chamber with solvent vapor. Only then is the slurry cast. As a result, the slurry remains fluid long enough to spread evenly over the casting surface formed by the chamber, and for the slurry particles to become densely packed. Only then is the chamber vented to remove solvent, so the slurry can dry. The major novel feature is applying solvent vapor to a rotating chamber before casting slurry against the chamber walls.

  17. Simulation Of Wave Function And Probability Density Of Modified Poschl Teller Potential Derived Using Supersymmetric Quantum Mechanics

    SciTech Connect

    Angraini, Lily Maysari; Suparmi,; Variani, Viska Inda

    2010-12-23

    SUSY quantum mechanics can be applied to solve Schrodinger equation for high dimensional system that can be reduced into one dimensional system and represented in lowering and raising operators. Lowering and raising operators can be obtained using relationship between original Hamiltonian equation and the (super) potential equation. In this paper SUSY quantum mechanics is used as a method to obtain the wave function and the energy level of the Modified Poschl Teller potential. The graph of wave function equation and probability density is simulated by using Delphi 7.0 programming language. Finally, the expectation value of quantum mechanics operator could be calculated analytically using integral form or probability density graph resulted by the programming.

  18. Bone Density Testing (Beyond the Basics)

    MedlinePlus

    ... of Use ©2016 UpToDate, Inc. Patient education: Bone density testing (Beyond the Basics) Author Michael Kleerekoper, MD ... last updated: Sep 22, 2015. WHAT DOES BONE DENSITY TESTING DO AND WHY IS IT IMPORTANT? — People ...

  19. Breast Density and Your Breast Mammogram Report

    MedlinePlus

    Breast Density and Your Mammogram Report Regular mammograms are the best way to find breast cancer early. But if ... But in some women, there’s little change. Breast density is very common, and is not abnormal. How ...

  20. Electronic structures and optical properties of TiO2: Improved density-functional-theory investigation

    NASA Astrophysics Data System (ADS)

    Gong, Sai; Liu, Bang-Gui

    2012-05-01

    TiO2 has been recently used to realize high-temperature ferromagnetic semiconductors. In fact, it has been widely used for a long time as white pigment and sunscreen because of its whiteness, high refractive index, and excellent optical properties. However, its electronic structures and the related properties have not been satisfactorily understood. Here, we use Tran and Blaha's modified Becke-Johnson (TB-mBJ) exchange potential (plus a local density approximation correlation potential) within the density functional theory to investigate electronic structures and optical properties of rutile and anatase TiO2. Our comparative calculations show that the energy gaps obtained from mBJ method agree better with the experimental results than that obtained from local density approximation (LDA) and generalized gradient approximation (GGA), in contrast with substantially overestimated values from many-body perturbation (GW) calculations. As for optical dielectric functions (both real and imaginary parts), refractive index, and extinction coefficients as functions of photon energy, our mBJ calculated results are in excellent agreement with the experimental curves. Our further analysis reveals that these excellent improvements are achieved because mBJ potential describes accurately the energy levels of Ti 3d states. These results should be helpful to understand the high temperature ferromagnetism in doped TiO2. This approach can be used as a standard to understand electronic structures and the related properties of such materials as TiO2.

  1. Nonlinear density waves in planetary rings

    NASA Technical Reports Server (NTRS)

    Borderies, Nicole; Goldreich, Peter; Tremaine, Scott

    1986-01-01

    The steady-state structure of planetary rings in the presence of density waves at the Lindblad resonances of a satellite is indicated. The study is based on the dispersion relation and damping rate for nonlinear density waves, derived by Shu et al. (1985) and by Borderies, Goldreich, and Tremaine (1985). It is shown that strong density waves lead to an enhancement of the background surface density in the wave zone.

  2. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested.

  3. Density dependence of nuclear symmetry energy

    NASA Astrophysics Data System (ADS)

    Behera, B.; Routray, T. R.; Tripathy, S. K.

    2016-10-01

    High density behavior of nuclear symmetry energy is studied on the basis of the stiffest density dependence of asymmetric contribution to energy per nucleon in charge neutral n + p + e + μ matter under beta equilibrium. The density dependence of nuclear symmetry energy obtained in this way is neither very stiff nor soft at high densities and is found to be in conformity with recent observations of neutron stars.

  4. Chernoff's density is log-concave.

    PubMed

    Balabdaoui, Fadoua; Wellner, Jon A

    2014-02-01

    We show that the density of Z = argmax{W (t) - t(2)}, sometimes known as Chernoff's density, is log-concave. We conjecture that Chernoff's density is strongly log-concave or "super-Gaussian", and provide evidence in support of the conjecture.

  5. Crowding and Neighborhood Mediation of Urban Density.

    ERIC Educational Resources Information Center

    Baum, Andrew; And Others

    The study of density and crowding has expanded rapidly, due in part to concern about the impact of high density on the quality of life. In this paper results of a study which focused upon the intervening role of neighborhood variables in the experience of urban density are reported. Residents of moderately dense urban areas were surveyed and…

  6. Record high Wolf, Canis lupus, pack density

    USGS Publications Warehouse

    Mech, L.D.; Tracy, S.

    2004-01-01

    This report documents a year-around Wolf (Canis lupus) density of 18.2/100 km2 and a summer density of 30.8/100 km2, in a northeastern Minnesota Wolf pack. The previous record was a summer density of 14.1/100 km2, for a Wolf pack on Vancouver Island, British Columbia, Canada.

  7. Record high wolf, Canis lupus, pack density

    USGS Publications Warehouse

    Mech, L.D.; Tracy, S.

    2004-01-01

    This report documents a year-around wolf (Canis lupus) density of 18.2/100 m2 and summer density of 30.8/100 km2, in a northeastern Minnesota wolf pack. The previous record was a summer density of 14.1/100 km2, for a wolf pack on Vancouver Island, BC, Canada.

  8. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  9. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  10. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  11. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  12. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field is, in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations (such that the Boussinesq approximation is not valid). In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For this case, the pdf of the density becomes asymmetric about its mean value during the early stages of its evolution. It is argued that these asymmetries in the pdf of the density field are due to different entrainment rates, into the mixing region, that favor the high speed fluid.

  13. Hyperon matter at low densities

    SciTech Connect

    Sulaksono, A.

    2014-09-25

    It was reported recently that hyperons can be present inside PSRJ1614-2230 compact star. This can be realized only if the strength of the ω-hyperons and φ-hyperons coupling of conventional hyperons coupling constant on the extended relativistic mean field (ERMF) model increase by a factor of 1.5 to 3. In the present work, the mass and radius relation of the neutron star that is calculated by using BSR28 parameter set of ERMF model augmented with maximal coupling strength of the ω-hyperons and φ-hyperons (X=1), is compared to the mass and radius relation of the neutron star that is predicted by the same RMF parameter set but by assuming that hyperons do not exist in the matter (No. Hyp) as well as those by assuming the hyperons coupling constant fulfilled the conventional SU(6) and SU(3) symmetry. The consequences of implementing X=1 prescription are also discussed. The potential depths of hyperons in symmetric nuclear matter (SNM), pure neutron matter (PNM) and pure lambda matter (PLM) based on this parameter set are also calculated by using the X=1, SU (6) and SU (3) prescriptions. The results are compared to those obtained from microscopic models, quark meson coupling model (χ QMM) and the QCD sum rule for finite density (QCD SM) result.

  14. Surfing the High Density Universe

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1998-01-01

    The central theme of the proposed research is to link what we know about galaxy clusters and large-scale structure in the local Universe at z less than 0.1 to what we know about the original fluctuations that led to this structure as observed in the cosmic microwave background. The simple-minded approach to this question (the kind I always take) is to took at structure in the regime 0.1 less than z less than 1000. We have a unique resource to help us in this task in the form of the VLA FIRST radio survey in which, to date, we have completed mapping nearly 5000 deg2 of the northern sky to a 20 cm flux density limit of 1.0 mJy. The 435,000 radio sources detected all have positions accurate to better than 1. As this report is written, we are obtaining the next - 1000 deg 2 of data; the goal of the survey is to complete the full 10,000 deg 2 to be covered in the Sloan Digital Sky Survey.

  15. Hyperon matter at low densities

    NASA Astrophysics Data System (ADS)

    Sulaksono, A.

    2014-09-01

    It was reported recently that hyperons can be present inside PSRJ1614-2230 compact star. This can be realized only if the strength of the ω-hyperons and φ-hyperons coupling of conventional hyperons coupling constant on the extended relativistic mean field (ERMF) model increase by a factor of 1.5 to 3. In the present work, the mass and radius relation of the neutron star that is calculated by using BSR28 parameter set of ERMF model augmented with maximal coupling strength of the ω-hyperons and φ-hyperons (X=1), is compared to the mass and radius relation of the neutron star that is predicted by the same RMF parameter set but by assuming that hyperons do not exist in the matter (No. Hyp) as well as those by assuming the hyperons coupling constant fulfilled the conventional SU(6) and SU(3) symmetry. The consequences of implementing X=1 prescription are also discussed. The potential depths of hyperons in symmetric nuclear matter (SNM), pure neutron matter (PNM) and pure lambda matter (PLM) based on this parameter set are also calculated by using the X=1, SU (6) and SU (3) prescriptions. The results are compared to those obtained from microscopic models, quark meson coupling model (χ QMM) and the QCD sum rule for finite density (QCD SM) result.

  16. Microvessels Density in Uterine Leiomyosarcoma

    PubMed Central

    Bobiński, Marcin; Bednarek, Wiesława; Szumiło, Justyna; Cybulski, Marek; Polak, Grzegorz; Kotarski, Jan

    2015-01-01

    Uterine leiomyosarcomas (LMS) are rare tumors typically presenting rapid growth and unfavorable outcome. Nowadays the results of uterine LMS treatment do not meet expectations. Angiogenesis is one of processes investigated to be target for future treatment. The aim of the research was to assess microvessels density (MVD) in tumor samples collected from 50 patients with histological confirmed uterine leiomyosarcoma and to investigate statistical relations between MVD, patients survival, and FIGO stage of tumor. The assessment was carried out using immunohistochemistry methods with anti-CD34 antibody. No significant difference in MVD between FIGO stages was observed. Furthermore, contrary to many other malignancies, we found no significant relation between MVD and patients overall and 2-year survival. Results obtained in the study suggest that processes on vascular mimicry and mesenchymal to epithelial transition (MET) may play important role in development of LMS. No statistical relation between MVD and survival leads to conclusion that not only angiogenesis but other mechanisms as well should be taken into consideration in planning future research. PMID:26161403

  17. Finding Density Functionals with Machine Learning

    NASA Astrophysics Data System (ADS)

    Snyder, John C.; Rupp, Matthias; Hansen, Katja; Müller, Klaus-Robert; Burke, Kieron

    2012-06-01

    Machine learning is used to approximate density functionals. For the model problem of the kinetic energy of noninteracting fermions in 1D, mean absolute errors below 1kcal/mol on test densities similar to the training set are reached with fewer than 100 training densities. A predictor identifies if a test density is within the interpolation region. Via principal component analysis, a projected functional derivative finds highly accurate self-consistent densities. The challenges for application of our method to real electronic structure problems are discussed.

  18. Aerodynamic Focusing Of High-Density Aerosols

    SciTech Connect

    Ruiz, D. E.; Fisch, Nathaniel

    2014-02-24

    High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1 m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.

  19. Variable density turbulence tunnel facility.

    PubMed

    Bodenschatz, E; Bewley, G P; Nobach, H; Sinhuber, M; Xu, H

    2014-09-01

    The Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, produces very high turbulence levels at moderate flow velocities, low power consumption, and adjustable kinematic viscosity between 10(-4) m(2)/s and 10(-7) m(2)/s. The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. The highest kinematic viscosities, and hence lowest Reynolds numbers, are reached with air or nitrogen at 0.1 bar. To reach the highest Reynolds numbers the tunnel is pressurized to 15 bars with the dense gas sulfur hexafluoride (SF6). Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [M. Vallikivi, M. Hultmark, S. C. C. Bailey, and A. J. Smits, Exp. Fluids 51, 1521 (2011)]. We report measurements of the characteristic scales of the flow and of turbulent spectra up to Taylor Reynolds number R(λ) ≈ 1600, higher than any other grid-turbulence experiment. We also describe instrumentation under development, which includes an active grid and a Lagrangian particle tracking system that moves down the length of the tunnel with the mean flow. In this configuration, the properties of the turbulence are adjustable and its structure is resolvable up to R(λ) ≈ 8000.

  20. Bone Mineral Density in Schizophrenia

    PubMed Central

    Tseng, Ping-Tao; Chen, Yen-Wen; Yeh, Pin-Yang; Tu, Kun-Yu; Cheng, Yu-Shian; Wu, Ching-Kuan

    2015-01-01

    Abstract Numerous reports have discussed bone mineral density (BMD) or the risk of osteoporosis in schizophrenia, but have yielded only controversial results. We conducted an update of meta-analysis to examine the overall change in BMD in patients with schizophrenia and the effect on BMD of different antipsychotic drugs. Electronic research through platform of PubMed. The inclusion criteria were as follows: articles with relevance to comparisons of BMD in patients with schizophrenia (SCHIZ) and healthy controls (HCs), or articles discussing comparisons of BMD in SCHIZ receiving prolactin-raising (PR) and prolactin-sparing (PS) antipsychotics; articles about clinical trials. In the current meta-analysis, we used the random-effect model to pool the results from 13 studies comparing BMD in SCHIZ and in HCs, and the results from 7 studies comparing BMD in patients receiving PR and PS. Our results revealed significantly lower BMD in SCHIZ than in HCs (P < 0.001). In the meta-regression, mean age of subjects modulated the difference in BMD between patients and control subjects (P < 0.001). In addition, the BMD in SCHIZ taking PR was significantly lower than in those taking PS (P = 0.006). Our study can only point to the phenomenon that BMD in SCHIZ is lower than that in HCs, and cannot reveal any possible pathophysiology or mechanism of this phenomenon. In addition, we could not rule out the possible effect of medication on BMD based on the results of the meta-analysis of comparison of BMD in SCHIZ receiving PR and PS. The main result of our meta-analysis suggests that BMD is significantly lower in SCHIZ than in HCs. Our study emphasizes the importance of further screening for the risk of osteoporosis in young-aged schizophrenic patients, especially those taking PR, which are in high risk of fracture. PMID:26632691

  1. Density Distribution of Near Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Dotson, Jessie L.; Mathias, Donovan; Ostrowski, Daniel

    2016-10-01

    The density of near earth asteroids is a fundamental property which can illuminate the structure of the asteroid and is key in assessing the risk of an impact of an NEA with Earth. A low density can be indicative of a rubble pile structure whereas a higher density can imply a monolith and/or a higher metal content. Since the damage resulting from an impact of an asteroid with Earth depends on its interior structure and its total mass, density is a key parameter to understanding the risk of asteroid impact. Unfortunately, measuring the density of asteroids is extremely difficult, has only been attempted for a tiny fraction of NEAs and usually results in measurements with large uncertainties. In the absence of density measurements for a specific object, understanding the range and distribution of likely densities can allow for probabilistic assessment of the ensemble risk of an impact of an NEA and permit estimates of the range of reasonable masses for specific object. We have developed a candidate density distribution for near earth asteroids based on measurements of meteorite densities and an assumed range of macroporosities. Bayesian inference and existing near earth asteroid density measurements are used to develop an updated distribution.

  2. Dynamic Density: An Air Traffic Management Metric

    NASA Technical Reports Server (NTRS)

    Laudeman, I. V.; Shelden, S. G.; Branstrom, R.; Brasil, C. L.

    1998-01-01

    The definition of a metric of air traffic controller workload based on air traffic characteristics is essential to the development of both air traffic management automation and air traffic procedures. Dynamic density is a proposed concept for a metric that includes both traffic density (a count of aircraft in a volume of airspace) and traffic complexity (a measure of the complexity of the air traffic in a volume of airspace). It was hypothesized that a metric that includes terms that capture air traffic complexity will be a better measure of air traffic controller workload than current measures based only on traffic density. A weighted linear dynamic density function was developed and validated operationally. The proposed dynamic density function includes a traffic density term and eight traffic complexity terms. A unit-weighted dynamic density function was able to account for an average of 22% of the variance in observed controller activity not accounted for by traffic density alone. A comparative analysis of unit weights, subjective weights, and regression weights for the terms in the dynamic density equation was conducted. The best predictor of controller activity was the dynamic density equation with regression-weighted complexity terms.

  3. Simulation of nanoscale density fluctuations

    NASA Astrophysics Data System (ADS)

    Reiss, Howard; Bowles, Richard K.

    2000-11-01

    Problems associated with the simulation of density fluctuations of limited breadth in a small cell are exposed and studied. The fluctuations are viewed as "physical clusters" of the type that might appear in nucleation processes and related phenomena. One of the most important features of the study stems from the fact that the simulation of a small heterogeneity in a macroscopic system presents problems that do not occur in the simulation of a bulk homogeneous property of the system. For example, once having simulated the probability of appearance of the fluctuation in a small cell, how is that result to be "mapped" onto the macrosystem in order to specify the equilibrium number of such fluctuations in that system? This problem is closely associated with the proper separation of the translational and internal degrees of freedom of the system, and has arisen in a number of fields, including the theory of nucleation. There are other problems associated with exponential dependence of cluster probability on the work of formation of the cluster, and also with rareness of some important clusters. In the latter case, simulative "umbrella sampling" does not always solve the entire problem. The present study is confined to clusters that appear in rarefied gases. Such systems are important in a number of scenarios, including nucleation processes. Several cluster models are considered including those consisting of molecules confined to a "container" of fixed volume and those constructed on the center of mass of the cluster. Connections between them are derived and rigorous solutions to the mapping problem are derived. Quantitative measures for the accuracy of approximate solutions, applied to cases in which the cluster is compact, are provided and exact solutions are provided even for the noncompact case. Some surprising results emerge from the study, among which is the fact that a cluster whose location is determined by one of its molecules, does not always have a

  4. Intra- versus Inter-dimer Charge Inhomogeneity in the Triangular Lattice Compounds of β'-Cs[Pd(dmit)2]2: A Degree of Freedom Characteristic of an Interchange of Energy Levels in the Molecular Orbitals

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takashi; Tamura, Masafumi; Yakushi, Kyuya; Kato, Reizo

    2016-10-01

    We have carried out the complete analyses of the C=C stretching modes in the vibrational spectra in the triangular lattice of β'-Cs[Pd(dmit)2]2 in order to solve the puzzling phenomenon that the ground state is neither spin frustration nor anti-ferromagnetic state but octamerization. We found that both charge-rich and charge-poor dimers are non-centrosymmetric dimers with the inhomogeneous charges. Because the energy levels of HOMO and LUMO are interchanged due to the tight dimerization, the cooperative interaction between the inter-site Coulomb repulsions and the valence-bond formation operates within and between dimers, those which contribute to the inter-dimer and intra-dimer charge separations, respectively. Octamer is the minimal unit under both cooperative interactions. In the high-temperature phase of β'-Cs[Pd(dmit)2]2, the competition between octamerization and tetramerization is observed because of the suppression of the intra-dimer cooperative interaction. The competition between two different states indicates the degree of freedom characteristic of the molecular orbital due to the tight dimerization. The cooperative interactions of the various X[Pd(dmit)2]2 salts are quantitatively evaluated from the C=C stretching modes.

  5. Organic sensitizers from D-π-A to D-A-π-A: effect of the internal electron-withdrawing units on molecular absorption, energy levels and photovoltaic performances.

    PubMed

    Wu, Yongzhen; Zhu, Weihong

    2013-03-01

    The high performance and low cost of dye-sensitized solar cells (DSSCs) have drawn great interest from both academic and industrial circles. The research on exploring novel efficient sensitizers, especially on inexpensive metal-free pure organic dyes, has never been suspended. The donor-π bridge-acceptor (D-π-A) configuration is mainstream in the design of organic sensitizers due to its convenient modulation of the intramolecular charge-transfer nature. Recently, it has been found that incorporation of additional electron-withdrawing units (such as benzothiadiazole, benzotriazole, quinoxaline, phthalimide, diketopyrrolopyrrole, thienopyrazine, thiazole, triazine, cyanovinyl, cyano- and fluoro-substituted phenyl) into the π bridge as internal acceptors, termed the D-A-π-A configuration, displays several advantages such as tuning of the molecular energy levels, red-shift of the charge-transfer absorption band, and distinct improvement of photovoltaic performance and stability. We apply the D-A-π-A concept broadly to the organic sensitizers containing additional electron-withdrawing units between electron donors and acceptors. This review is projected to summarize the category of pure organic sensitizers on the basis of the D-A-π-A feature. By comparing the structure-property relationship of typical photovoltaic D-A-π-A dyes, the important guidelines in the design of such materials are highlighted.

  6. An AB Initio Study of SbH_2 and BiH_2: the Renner Effect, Spin-Orbit Coupling, Local Mode Vibrations and Rovibronic Energy Level Clustering in SbH_2

    NASA Astrophysics Data System (ADS)

    Ostojic, Bojana; Schwerdtfeger, Peter; Bunker, Phil; Jensen, Per

    2016-06-01

    We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH_2 and BiH_2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH_2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH_2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption [1,2]. For the heavier dihydride BiH_2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH_2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states. [1] X. Wang, P. F. Souter and L. Andrews, J. Phys. Chem. A 107, 4244-4249 (2003) [2] N. Basco and K. K. Lee, Spectroscopy Letters 1, 13-15 (1968)

  7. Normal and abnormal evolution of argon metastable density in high-density plasmas

    SciTech Connect

    Seo, B. H.; Kim, J. H.; You, S. J.

    2015-05-15

    A controversial problem on the evolution of Ar metastable density as a function of electron density (increasing trend versus decreasing trend) was resolved by discovering the anomalous evolution of the argon metastable density with increasing electron density (discharge power), including both trends of the metastable density [Daltrini et al., Appl. Phys. Lett. 92, 061504 (2008)]. Later, by virtue of an adequate physical explanation based on a simple global model, both evolutions of the metastable density were comprehensively understood as part of the abnormal evolution occurring at low- and high-density regimes, respectively, and thus the physics behind the metastable evolution has seemed to be clearly disclosed. In this study, however, a remarkable result for the metastable density behavior with increasing electron density was observed: even in the same electron density regime, there are both normal and abnormal evolutions of metastable-state density with electron density depending on the measurement position: The metastable density increases with increasing electron density at a position far from the inductively coupled plasma antenna but decreases at a position close to the antenna. The effect of electron temperature, which is spatially nonuniform in the plasma, on the electron population and depopulation processes of Argon metastable atoms with increasing electron density is a clue to understanding the results. The calculated results of the global model, including multistep ionization for the argon metastable state and measured electron temperature, are in a good agreement with the experimental results.

  8. Density-functional theory of thermoelectric phenomena.

    PubMed

    Eich, F G; Di Ventra, M; Vignale, G

    2014-05-16

    We introduce a nonequilibrium density-functional theory of local temperature and associated local energy density that is suited for the study of thermoelectric phenomena. The theory rests on a local temperature field coupled to the energy-density operator. We identify the excess-energy density, in addition to the particle density, as the basic variable, which is reproduced by an effective noninteracting Kohn-Sham system. A novel Kohn-Sham equation emerges featuring a time-dependent and spatially varying mass which represents local temperature variations. The adiabatic contribution to the Kohn-Sham potentials is related to the entropy viewed as a functional of the particle and energy density. Dissipation can be taken into account by employing linear response theory and the thermoelectric transport coefficients of the electron gas.

  9. ITER Experts' meeting on density limits

    SciTech Connect

    Borrass, K.; Igitkhanov, Y.L.; Uckan, N.A.

    1989-12-01

    The necessity of achieving a prescribed wall load or fusion power essentially determines the plasma pressure in a device like ITER. The range of operation densities and temperatures compatible with this condition is constrained by the problems of power exhaust and the disruptive density limit. The maximum allowable heat loads on the divertor plates and the maximum allowable sheath edge temperature practically impose a lower limit on the operating densities, whereas the disruptive density limit imposes an upper limit. For most of the density limit scalings proposed in the past an overlap of the two constraints or at best a very narrow accessible density range is predicted for ITER. Improved understanding of the underlying mechanisms is therefore a crucial issue in order to provide a more reliable basis for extrapolation to ITER and to identify possible ways of alleviating the problem.

  10. High Density Fuel Development for Research Reactors

    SciTech Connect

    Daniel Wachs; Dennis Keiser; Mitchell Meyer; Douglas Burkes; Curtis Clark; Glenn Moore; Jan-Fong Jue; Totju Totev; Gerard Hofman; Tom Wiencek; Yeon So Kim; Jim Snelgrove

    2007-09-01

    An international effort to develop, qualify, and license high and very high density fuels has been underway for several years within the framework of multi-national RERTR programs. The current development status is the result of significant contributions from many laboratories, specifically CNEA in Argentina, AECL in Canada, CEA in France, TUM in Germany, KAERI in Korea, VNIIM, RDIPE, IPPE, NCCP and RIARR in Russia, INL, ANL and Y-12 in USA. These programs are mainly engaged with UMo dispersion fuels with densities from 6 to 8 gU/cm3 (high density fuel) and UMo monolithic fuel with density as high as 16 gU/cm3 (very high density fuel). This paper, mainly focused on the French & US programs, gives the status of high density UMo fuel development and perspectives on their qualification.

  11. Quartz resonator fluid density and viscosity monitor

    DOEpatents

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

    1998-01-01

    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  12. Method of synthesizing a low density material

    DOEpatents

    Lorensen, L.E.; Monaco, S.B.

    1987-02-27

    A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.

  13. Adaptive density estimator for galaxy surveys

    NASA Astrophysics Data System (ADS)

    Saar, Enn

    2016-10-01

    Galaxy number or luminosity density serves as a basis for many structure classification algorithms. Several methods are used to estimate this density. Among them kernel methods have probably the best statistical properties and allow also to estimate the local sample errors of the estimate. We introduce a kernel density estimator with an adaptive data-driven anisotropic kernel, describe its properties and demonstrate the wealth of additional information it gives us about the local properties of the galaxy distribution.

  14. Poisson brackets for densities of functionals

    NASA Astrophysics Data System (ADS)

    Dickey, Leonid A.

    In the theory of integrable systems and in other field theories one usually deals with Poisson brackets between functionals. The latter are integrals of densities. Densities are defined up to divergence (boundary) terms. A question arises, is it possible to define a reasonable Poisson bracket for densities themselves? A general theory was suggested by Barnich, Fulp, Lada, Markl and Stasheff which has led them to the notion of a strong homotopy Lie group, (sh Lie). We are giving a few concrete examples.

  15. Observation of density-induced tunneling.

    PubMed

    Jürgensen, Ole; Meinert, Florian; Mark, Manfred J; Nägerl, Hanns-Christoph; Lühmann, Dirk-Sören

    2014-11-01

    We study the dynamics of bosonic atoms in a tilted one-dimensional optical lattice and report on the first direct observation of density-induced tunneling. We show that the interaction affects the time evolution of the doublon oscillation via density-induced tunneling and pinpoint its density and interaction dependence. The experimental data for different lattice depths are in good agreement with our theoretical model. Furthermore, resonances caused by second-order tunneling processes are studied, where the density-induced tunneling breaks the symmetric behavior for attractive and repulsive interactions predicted by the Hubbard model.

  16. Are there optimal densities for prairie birds?

    USGS Publications Warehouse

    Skagen, S.K.; Adams, A.A.Y.

    2010-01-01

    The major forces of food and predation shape fitness-enhancing decisions of birds at all stages of their life cycles. During the breeding season, birds can minimize nest loss due to predation by selecting sites with a lower probability of predation. To understand the environmental and social aspects and consequences of breedingsite selection in prairie birds, we explored variation in nest-survival patterns of the Lark Bunting (Calamospiza melanocorys) in the shortgrass prairie region of North America. Over four breeding seasons, we documented the survival of 405 nests, conducted 60 surveys to estimate bird densities, and measured several vegetative features to describe habitat structure in 24 randomly selected study plots. Nest survival varied with the buntings' density as described by a quadratic polynomial, increasing with density below 1.5 birds ha-1 and decreasing with density between 1.5 and 3 birds ha-1, suggesting that an optimal range of densities favors reproductive success of the Lark Bunting, which nests semi-colonially. Nest survival also increased with increasing vegetation structure of study plots and varied with age of the nest, increasing during early incubation and late in the nestling stage and declining slightly from mid-incubation to the middle of the nestling period. The existence of an optimal range of densities in this semi-colonial species can be elucidated by the "commodity-selection hypothesis" at low densities and density dependence at high densities. ?? The Cooper Ornithological Society 2010.

  17. Observation of density-induced tunneling.

    PubMed

    Jürgensen, Ole; Meinert, Florian; Mark, Manfred J; Nägerl, Hanns-Christoph; Lühmann, Dirk-Sören

    2014-11-01

    We study the dynamics of bosonic atoms in a tilted one-dimensional optical lattice and report on the first direct observation of density-induced tunneling. We show that the interaction affects the time evolution of the doublon oscillation via density-induced tunneling and pinpoint its density and interaction dependence. The experimental data for different lattice depths are in good agreement with our theoretical model. Furthermore, resonances caused by second-order tunneling processes are studied, where the density-induced tunneling breaks the symmetric behavior for attractive and repulsive interactions predicted by the Hubbard model. PMID:25415904

  18. 3-D capacitance density imaging system

    DOEpatents

    Fasching, G.E.

    1988-03-18

    A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.

  19. Density-dependent adjustment of inducible defenses

    PubMed Central

    Tollrian, Ralph; Duggen, Sonja; Weiss, Linda C.; Laforsch, Christian; Kopp, Michael

    2015-01-01

    Predation is a major factor driving evolution, and organisms have evolved adaptations increasing their survival chances. However, most defenses incur trade-offs between benefits and costs. Many organisms save costs by employing inducible defenses as responses to fluctuating predation risk. The level of defense often increases with predator densities. However, individual predation risk should not only depend on predator density but also on the density of conspecifics. If the predator has a saturating functional response one would predict a negative correlation between prey density and individual predation risk and hence defense expression. Here, we tested this hypothesis using six model systems, covering a taxonomic range from protozoa to rotifers and crustaceans. In all six systems, we found that the level of defense expression increased with predator density but decreased with prey density. In one of our systems, i.e. in Daphnia, we further show that the response to prey density is triggered by a chemical cue released by conspecifics and congeners. Our results indicate that organisms adjust the degree of defense to the acute predation risk, rather than merely to predators’ densities. Our study suggests that density-dependent defense expression reflects accurate predation-risk assessment and is a general principle in many inducible-defense systems. PMID:26235428

  20. Density determination from far-infrared lines

    NASA Technical Reports Server (NTRS)

    Rubin, Robert H.; Simpson, Janet P.; Erickson, Edwin F.; Haas, Michael R.; Lord, Steven D.; Colgan, Sean W. J.

    1995-01-01

    We demonstrate that when there are gas density variations within a nebula, various line ratios used to determine electron density (Ne) can give different results. When there are non-constant density conditions, it is shown that by using one (average) Ne, significant, systematic biases may occur in the derived chemical abundance ratios. The abundance ratio of a heavy element (when a collisionally excited line is used) to ionized hydrogen may be subject to a large underestimate in the presence of density fluctuations. The more Ne-diagnostic observations made, the more reliable will be the deciphering of the actual Ne variation throughout a nebula.

  1. Density limit studies on DIII-D

    SciTech Connect

    Maingi, R.; Mahdavi, M.A.; Petrie, T.W.

    1998-08-01

    The authors have studied the processes limiting plasma density and successfully achieved discharges with density {approximately}50% above the empirical Greenwald density limit with H-mode confinement. This was accomplished by density profile control, enabled through pellet injection and divertor pumping. By examining carefully the criterion for MARFE formation, the authors have derived an edge density limit with scaling very similar to Greenwald scaling. Finally, they have looked in detail at the first and most common density limit process in DIII-D, total divertor detachment, and found that the local upstream separatrix density (n{sub e}{sup sep,det}) at detachment onset (partial detachment) increases with the scrape-off layer heating power, P{sub heat}, i.e., n{sub e}{sup sep,det} {approximately} P{sub heat}{sup 0.76}. This is in marked contrast to the line-average density at detachment which is insensitive to the heating power. The data are in reasonable agreement with the Borass model, which predicted that the upstream density at detachment would increase as P{sub heat}{sup 0.7}.

  2. High density harp for SSCL linac

    SciTech Connect

    Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

    1993-05-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities.

  3. Calculating Atomic Number Densities for Uranium

    1993-01-01

    Provides method to calculate atomic number densities of selected uranium compounds and hydrogenous moderators for use in nuclear criticality safety analyses at gaseous diffusion uranium enrichment facilities.

  4. Bone density in eumenorrheic female college athletes.

    PubMed

    Risser, W L; Lee, E J; LeBlanc, A; Poindexter, H B; Risser, J M; Schneider, V

    1990-10-01

    Information is limited on the effect of exercise on bone density in young eumenorrheic athletes. We studied 12 Caucasian intercollegiate volleyball players (V), nine basketball players (B), ten swimmers (S), and 13 non-athletes (N) with bone density measurements by photon absorptiometry of their calcaneus and lumbar spine (L2-L4). The effect of athletic status on bone density was analyzed by multivariate analysis of covariance, with height and weight as covariates. The bone densities reported below are mean +/- SE, adjusted for the covariates; units = g.cm-2, P less than 0.005. The swimmers had a significantly lower mean density in the lumbar spine than all other groups; the non-athletes' mean density was also lower than that of volleyball players (V = 1.31 +/- 0.03, B = 1.26 +/- 0.04, N = 1.18 +/- 0.03, S = 1.05 +/- 0.03). The volleyball and basketball players' mean calcaneal densities were greater than those of the swimmers and non-athletes (V = 0.530 +/- 0.017, B = 0.564 +/- 0.023, N = 0.438 +/- 0.018, S = 0.375 +/- 0.019). The higher bone densities for athletes in vertical weight-bearing activities are consistent with some but not all published data. The swimmers' low bone density in the lumbar spine, less than published values for amenorrheic runners, was unexpected.

  5. A Universal Density Structure for Circumgalactic Gas

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Hennawi, Joseph F.; Prochaska, J. Xavier; Werk, Jessica K.

    2016-10-01

    We develop a new method to constrain the physical conditions in the cool (∼104 K) circumgalactic medium (CGM) from measurements of ionic column densities by assuming that the cool CGM spans a large range of gas densities and that small high-density clouds are hierarchically embedded in large low-density clouds. The new method combines the information available from different sightlines during the photoionization modeling, thus yielding tighter constraints on CGM properties compared to traditional methods that model each sightline individually. Applying this new technique to the COS Halos survey of low-redshift ∼L* galaxies, we find that we can reproduce all observed ion columns in all 44 galaxies in the sample, from the low ions to {{O}} {{VI}}, with a single universal density structure for the cool CGM. The gas densities span the range 50≲ ρ /{\\bar{ρ }}b≲ 5× {10}5 ({\\bar{ρ }}b is the cosmic mean), while the physical size of individual clouds scales as ∼ρ ‑1, from ≈35 kpc for the low-density {{O}} {{VI}} clouds to ≈6 pc for the highest-density low-ion clouds. The deduced cloud sizes are too small for this density structure to be driven by self-gravity; thus, its physical origin is unclear. The implied cool CGM mass within the virial radius is (1.3 ± 0.4) × 1010 {M}ȯ (∼1% of the halo mass), distributed rather uniformly over the 4 decades in density. The mean cool gas density profile scales as {R}-1.0+/- 0.3, where R is the distance from the galaxy center. We construct a 3D model of the cool CGM based on our results, which we argue provides a benchmark for the CGM structure in hydrodynamic simulations. Our results can be tested by measuring the coherence scales of different ions.

  6. Density-of-states effective mass and scattering parameter measurements by transport phenomena in thin films

    NASA Astrophysics Data System (ADS)

    Young, D. L.; Coutts, T. J.; Kaydanov, V. I.

    2000-02-01

    A novel machine has been developed to measure transport coefficients in the temperature range of 50-350 K of thin films deposited on electrically insulating substrates. The measured coefficients—resistivity, Hall, Seebeck, and Nernst—are applied to solutions of the Boltzmann transport equation to give information about the film's density-of-states effective mass, the Fermi energy level, and an energy-dependent scattering parameter. The machine is designed to eliminate or compensate for simultaneously occurring transport phenomena that would interfere with the desired measured quantity, while allowing for all four coefficients to be measured on the same sample. An average density-of-states effective mass value of 0.29±0.04me was measured on the transparent conductive oxide, cadmium stannate (CTO), over a carrier concentration range of 2-7×1020cm-3. This effective mass value matched previous results obtained by optical and thermoelectric modeling. The measured scattering parameter indicates that neutral impurities or a mixture of scattering mechanisms may inhibit the transport of carriers in CTO.

  7. Reduced vertebral bone density in hypercalciuric nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Pietschmann, F.; Breslau, N. A.; Pak, C. Y.

    1992-01-01

    Dual-energy x-ray absorptiometry and single-photon absorptiometry were used to determine bone density at the lumbar spine and radial shaft in 62 patients with absorptive hypercalciuria, 27 patients with fasting hypercalciuria, and 31 nonhypercalciuric stone formers. Lumbar bone density was significantly lower in patients with absorptive (-10%) as well as in those with fasting hypercalciuria (-12%), with 74 and 92% of patients displaying values below the normal mean, whereas only 48% of the nonhypercalciuric stone formers had bone density values below the normal mean. In contrast, radial bone density was similar in all three groups of renal stone formers investigated. The comparison of urinary chemistry in patients with absorptive hypercalciuria and low normal bone density compared to those with high normal bone density showed a significantly increased 24 h urinary calcium excretion on random diet and a trend toward a higher 24 h urinary uric acid excretion and a higher body mass index in patients with low normal bone density. Moreover, among the patients with absorptive hypercalciuria we found a statistically significant correlation between the spinal bone density and the 24 h sodium and sulfate excretion and the urinary pH. These results gave evidence for an additional role of environmental factors (sodium and animal proteins) in the pathogenesis of bone loss in absorptive hypercalciuria. In conclusion, our data suggest an osteopenia of trabecular-rich bone tissues in patients with fasting and absorptive hypercalciurias.

  8. Density Gradient Columns for Chemical Displays.

    ERIC Educational Resources Information Center

    Guenther, William B.

    1986-01-01

    Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

  9. The density and thickness of quiescent prominences

    NASA Technical Reports Server (NTRS)

    Hirayama, Tadashi

    1986-01-01

    The electron density was determined for a number of quiescent prominences at various positions from the Stark effect. It was found that the intensity ratio of Mg I emission lines to SrII lines is independent of the observed electron density in the range of ten to the 10.2 power to 10 to the 11.4 power cm-3. This contrasts with Landman's (1984) theoretical expectation that the ratio is proportional to the electron density. From the intensity of Balmer lines and the electron density, it is inferred that the true diameter of a thread in prominence of high electron density may be smaller than 0.2". The averaged total number density of hydrogen N sub H sub of was found to be 3-6 times 10 to the 11th power cm-3, leading to a total gas pressure P =0.6 dyn cm-2 and a total density of approx. 10 to the minus twelth power g cm-3. Landman's large value of N sub H approx. 6 times 10 to the 12th power and P sub g approx. 6 may have resulted either from the fact that he has treated very bright prominences and/or from the derivation of the high electron density for all prominences he studied.

  10. Consequences of Residential Density for Urban Life.

    ERIC Educational Resources Information Center

    Marans, Robert W.; Zehner, Robert B.

    Typical objectives of urban planners are reviewed and 3 are selected as relevant to this study which focuses on density as a measure of the number of dwellings per given land area, as distinguished from number of persons per room. Those selected: (1) consider the juxtaposition of housing and other land uses; (2) relate density to desired patterns…

  11. Locality of correlation in density functional theory.

    PubMed

    Burke, Kieron; Cancio, Antonio; Gould, Tim; Pittalis, Stefano

    2016-08-01

    The Hohenberg-Kohn density functional was long ago shown to reduce to the Thomas-Fermi (TF) approximation in the non-relativistic semiclassical (or large-Z) limit for all matter, i.e., the kinetic energy becomes local. Exchange also becomes local in this limit. Numerical data on the correlation energy of atoms support the conjecture that this is also true for correlation, but much less relevant to atoms. We illustrate how expansions around a large particle number are equivalent to local density approximations and their strong relevance to density functional approximations. Analyzing highly accurate atomic correlation energies, we show that EC → -AC ZlnZ + BCZ as Z → ∞, where Z is the atomic number, AC is known, and we estimate BC to be about 37 mhartree. The local density approximation yields AC exactly, but a very incorrect value for BC, showing that the local approximation is less relevant for the correlation alone. This limit is a benchmark for the non-empirical construction of density functional approximations. We conjecture that, beyond atoms, the leading correction to the local density approximation in the large-Z limit generally takes this form, but with BC a functional of the TF density for the system. The implications for the construction of approximate density functionals are discussed. PMID:27497544

  12. Coaxial capacitor used to determine fluid density

    NASA Technical Reports Server (NTRS)

    Atkisson, E. A.

    1965-01-01

    Sensing device measures directly the density of compressible fluid existing simultaneously in both liquid and gaseous phases. The device is comprised of a capacitor connected as one leg of a bridge circuit, a power source, and an indicator calibrated to indicate density as a direct measurement.

  13. Enhancing critical current density of cuprate superconductors

    DOEpatents

    Chaudhari, Praveen

    2015-06-16

    The present invention concerns the enhancement of critical current densities in cuprate superconductors. Such enhancement of critical current densities include using wave function symmetry and restricting movement of Abrikosov (A) vortices, Josephson (J) vortices, or Abrikosov-Josephson (A-J) vortices by using the half integer vortices associated with d-wave symmetry present in the grain boundary.

  14. Molar volumes and densities of minerals

    USGS Publications Warehouse

    Robie, Richard A.; Bethke, Philip M.

    1962-01-01

    These tables present critically chosen "best values" for the density and molar volume of selected mineral compounds. No attempt was made to be all-inclusive; rather we have tried to present data for chemically and physically well-defined phases for which the molar volume and/or density was knovvn to the order of 0. 2 percent.

  15. Electron density studies of methyl cellobioside

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experimental X-ray diffraction crystallography determines the variations in electron density that result from the periodic array of atoms in a crystal. Normally, the positions and type of atom are determined from the electron density based on an approximation that the atoms are spherical. However, t...

  16. High bandwidth vapor density diagnostic system

    DOEpatents

    Globig, Michael A.; Story, Thomas W.

    1992-01-01

    A high bandwidth vapor density diagnostic system for measuring the density of an atomic vapor during one or more photoionization events. The system translates the measurements from a low frequency region to a high frequency, relatively noise-free region in the spectrum to provide improved signal to noise ratio.

  17. Preschoolers' Reasoning about Density: Will It Float?

    ERIC Educational Resources Information Center

    Kohn, Amy S.

    1993-01-01

    A buoyancy prediction test was developed to access preschoolers' early understanding of density. Two- to five-year-olds and college students make predictions about the buoyancy of a set of objects that varied in density, weight, and volume. Found that children aged four and five demonstrated patterns of judgment similar to those of the college…

  18. Locality of correlation in density functional theory

    NASA Astrophysics Data System (ADS)

    Burke, Kieron; Cancio, Antonio; Gould, Tim; Pittalis, Stefano

    2016-08-01

    The Hohenberg-Kohn density functional was long ago shown to reduce to the Thomas-Fermi (TF) approximation in the non-relativistic semiclassical (or large-Z) limit for all matter, i.e., the kinetic energy becomes local. Exchange also becomes local in this limit. Numerical data on the correlation energy of atoms support the conjecture that this is also true for correlation, but much less relevant to atoms. We illustrate how expansions around a large particle number are equivalent to local density approximations and their strong relevance to density functional approximations. Analyzing highly accurate atomic correlation energies, we show that EC → -AC ZlnZ + BCZ as Z → ∞, where Z is the atomic number, AC is known, and we estimate BC to be about 37 mhartree. The local density approximation yields AC exactly, but a very incorrect value for BC, showing that the local approximation is less relevant for the correlation alone. This limit is a benchmark for the non-empirical construction of density functional approximations. We conjecture that, beyond atoms, the leading correction to the local density approximation in the large-Z limit generally takes this form, but with BC a functional of the TF density for the system. The implications for the construction of approximate density functionals are discussed.

  19. Microinstabilities in weak density gradient tokamak systems

    SciTech Connect

    Tang, W.M.; Rewoldt, G.; Chen, L.

    1986-04-01

    A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

  20. Electron (charge) density studies of cellulose models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introductory material first describes electron density approaches and demonstrates visualization of electron lone pairs and bonding as concentrations of electron density. Then it focuses on the application of Bader’s Quantum Theory of Atoms-in-Molecules (AIM) to cellulose models. The purpose of the ...