Interactive Molecular Orbital Diagrams
NSDL National Science Digital Library
Here is an application for constructing the molecular orbital electron configurations of heteronuclear diatomic molecules. Energy level diagrams are given for the two different cases encountered in heteronuclear diatomics of the first short period (Li2 - Ne2). This is a useful tool for having students explore questions of bond order, magnetic properties and numbers of unpaired electrons.
J. I Pascual; J Gómez-Herrero; C Rogero; A. M Baró; D Sánchez-Portal; E Artacho; P Ordejón; J. M Soler
2000-01-01
We present results on a well known system, C60 on Si(111)(7×7), which show that the scanning tunneling microscope (STM) is probing a single molecular orbital (MO). This MO, after comparison of experimental intramolecular structure with ab initio calculations, arises from the highest occupied MO (HOMO). The adsorbed molecules keep their relevant electronic identity but suffer a decrease in their icosahedral
ISS EPS Orbital Replacement Unit Block Diagrams
NASA Technical Reports Server (NTRS)
Schmitz, Gregory V.
2001-01-01
The attached documents are being provided to Switching Power Magazine for information purposes. This magazine is writing a feature article on the International Space Station Electrical Power System, focusing on the switching power processors. These units include the DC-DC Converter Unit (DDCU), the Bi-directional Charge/Discharge Unit (BCDU), and the Sequential Shunt Unit (SSU). These diagrams are high-level schematics/block diagrams depicting the overall functionality of each unit.
Heteronuclear Diatomic Molecular Orbital Formation
NSDL National Science Digital Library
Here is a set of movies that demonstrates heteronuclear diatomic molecular orbital formation. The orbitals start at a distance where there is little or no interatomic interaction and move to the appropriate bond distance. Orbital phase is shown by the different colors.
Simulation of Atomic and Molecular Orbitals
ERIC Educational Resources Information Center
Massey, A. G.; Massey S.
1976-01-01
Describes the use of magnets to simulate s, p, and d atomic orbitals from which a wide variety of molecular orbitals can be derived. The technique gives students an idea of molecular orbitals' shapes and stresses the importance of symmetry labels. (MLH)
Some Observations on Molecular Orbital Theory
ERIC Educational Resources Information Center
Journal of Chemical Education, 2005
2005-01-01
A few flawed predictions in the context of homonuclear diatomic molecules are presented in order to introduce students to molecular orbital (MO) theory. A common misrepresentation of the relationship between the energy of an atomic orbital and the energy of the MO associated with the atomic orbital is illustrated.
A Simple Huckel Molecular Orbital Plotter
ERIC Educational Resources Information Center
Ramakrishnan, Raghunathan
2013-01-01
A program is described and presented to readily plot the molecular orbitals from a Huckel calculation. The main features of the program and the scope of its applicability are discussed through some example organic molecules. (Contains 2 figures.)
Simple orbital theory for the molecular electrician
Matthias Ernzerhof
2011-01-01
Theories of molecular electronic devices (MEDs) are quite involved in general. However, various prominent features of MEDs can be understood drawing only on elementary quantum theory. To support this point of view, we provide a two component orbital theory that enables one to reproduce various important features of MEDs. In this theory, the device orbitals are divided into two components,
How Different Variants of Orbit Diagrams Influence Student Explanations of the Seasons
ERIC Educational Resources Information Center
Lee, Victor R.
2010-01-01
The cause of the seasons is often associated with a very particular alternative conception: That the earth's orbit around the sun is highly elongated, and the differences in distance result in variations in temperature. It has been suggested that the standard diagrams used to depict the earth's orbit may be in some way responsible for the initial…
Molecular Electronic Terms and Molecular Orbital Configurations.
ERIC Educational Resources Information Center
Mazo, R. M.
1990-01-01
Discussed are the molecular electronic terms which can arise from a given electronic configuration. Considered are simple cases, molecular states, direct products, closed shells, and open shells. Two examples are provided. (CW)
Molecular Complexation and Phase Diagrams of Urea/PEG Mixtures
NASA Astrophysics Data System (ADS)
Fu, Guoepeng; Kyu, Thein
2014-03-01
Polyethylene glycol (PEG) and urea complexation has been known to form a stable crystal due to molecular complexation. The effect of molecular weight of PEG on the phase diagrams of its blends with urea has been explored. In the case of high molecular weight PEG8k/urea, the observed phase diagram is azeotrope, accompanied by eutectoid reactions in the submerged phases such as induced stable ``alpha'' phase crystals and metastable ``beta'' phase crystals. The metastable crystal can transform to stable crystal under a certain thermal annealing condition. However, the phase diagram of PEG1k/urea is of coexistence loop, whereas PEG400/urea exhibits eutectic character. Subsequently, the change of azeotrope to eutectic behavior with PEG molecular weight is analyzed in the context of the combined Flory-Huggins theory of liquid-liquid demixing and phase field theory of crystal solidification. Of particular interest is that only a very small urea amount (2 wt%) is needed to form a stable inclusion crystal via complexation with PEG. Potential application in lithium battery is discussed based on AC impedance spectroscopy and cyclic voltammetry. Supported by NSF-DMR 1161070.
ERIC Educational Resources Information Center
Orenha, Renato P.; Galembeck, Sérgio E.
2014-01-01
This computational experiment presents qualitative molecular orbital (QMO) and computational quantum chemistry exercises of NO, NO[superscript+], and NO[superscript-]. Initially students explore several properties of the target molecules by Lewis diagrams and the QMO theory. Then, they compare qualitative conclusions with EHT and DFT calculations…
Clore, G. Marius
MOLECULAR PHARMACOLOGY, 24:443-448 443 Ab Initio Molecular Orbital Calculations of Electron molecular orbital calculations of electron distribution in tetramethylammoniurn ion and its uncharged Divisions of Computing and Molecular Pharmacology, National Institute for Medical Research, Mill Hill
Phase diagram of interacting Fermi gas in spin–orbit coupled square lattices
NASA Astrophysics Data System (ADS)
Zhang, Xin; Wu, Wei; Li, Gang; Wen, Lin; Sun, Qing; Ji, An-Chun
2015-07-01
The spin–orbit (SO) coupled optical lattices have attracted considerable interest. In this paper, we investigate the phase diagram of the interacting Fermi gas with Rashba-type spin–orbit coupling (SOC) on a square optical lattice. The phase diagram is investigated in a wide range of atomic interactions and SOC strength within the framework of the cluster dynamical mean-field theory (CDMFT). We show that the interplay between the atomic interactions and SOC results in a rich phase diagram. In the deep Mott insulator regime, the SOC can induce diverse spin ordered phases. Whereas near the metal–insulator transition (MIT), the SOC tends to destroy the conventional antiferromagnetic fluctuations, giving rise to distinctive features of the MIT. Furthermore, the strong fluctuations arising from SOC may destroy the magnetic orders and trigger an order to disorder transition in close proximity of the MIT.
Simple orbital theory for the molecular electrician.
Ernzerhof, Matthias
2011-07-01
Theories of molecular electronic devices (MEDs) are quite involved in general. However, various prominent features of MEDs can be understood drawing only on elementary quantum theory. To support this point of view, we provide a two component orbital theory that enables one to reproduce various important features of MEDs. In this theory, the device orbitals are divided into two components, each of which is obtained from simple rules. To illustrate our two-component model, we apply it to explain, among other things, the conductance suppression in cross-conjugated systems and the dependence of the conductance on the contact position in aromatic systems. PMID:21744885
Spin–orbit interaction mediated molecular dissociation
Kokkonen, E. Jänkälä, K.; Kettunen, J. A.; Heinäsmäki, S.; Karpenko, A.; Huttula, M.; Löytynoja, T.; Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm
2014-05-14
The effect of the spin–orbit interaction to photofragmentation is investigated in the mercury(II) bromide (HgBr{sub 2}) molecule. Changes in the fragmentation between the two spin–orbit components of Hg 5d photoionization, as well as within the molecular-field-splitted levels of these components are observed. Dissociation subsequent to photoionization is studied with synchrotron radiation and photoelectron-photoion coincidence spectroscopy. The experimental results are accompanied by relativistic ab initio analysis of the photoelectron spectrum.
MOPAC: A semiempirical molecular orbital program
James J. P. Stewart
1990-01-01
Before we start, we need a working definition for MOPAC. The following description has been used many times to describe MOPAC: MOPAC is a general-purpose, semiempirical molecular orbital program for the study of chemical reactions involving molecules, ions, and linear polymers. It implements the semiempirical Hamiltonians MNDO, AM 1, MINDO\\/3, and MNDOPM3, and combir_es the calculations of vibrational spectra, thermodynamic
Molecular diagnosis of orbital inflammatory disease.
Rosenbaum, James T; Choi, Dongseok; Wilson, David J; Grossniklaus, Hans E; Sibley, Cailin H; Harrington, Christina A; Planck, Stephen R
2015-04-01
Orbital inflammatory diseases include thyroid eye disease (TED), granulomatosis with polyangiitis (GPA), sarcoidosis, and nonspecific orbital inflammation (NSOI). Histopathological diagnosis usually relies on the clinical context and is not always definitive. Gene expression profiling provides diagnostic and therapeutic information in several malignancies, but its role in evaluating nonmalignant disease is relatively untested. We hypothesized that gene expression profiling could provide diagnostic information for NSOI. We collected formalin-fixed, paraffin-embedded orbital biopsies from 10 institutions and 83 subjects including 25 with thyroid eye disease, 25 nonspecific orbital inflammation, 20 healthy controls, 6 with granulomatosis with polyangiitis, and 7 with sarcoidosis. Tissues were divided into discovery and validation sets. Gene expression was quantified using Affymetrix U133 Plus 2.0 microarrays. A random forest statistical algorithm based on data from 39 probe sets identified controls, GPA, or TED with an average accuracy of 76% (p=0.02). Random forest analysis indicated that 52% of tissues from patients with nonspecific inflammation were consistent with a diagnosis of GPA. Molecular diagnosis by gene expression profiling will augment clinical data and histopathology in differentiating forms of orbital inflammatory disease. PMID:25595914
Simons, Jack
. Unlike most texts on molecular orbital theory and quantum mechanics, this text treats polyatomicSection 2 Simple Molecular Orbital Theory In this section, the conceptual framework of molecular orbital theory is developed. Applications are presented and problems are given and solved within
Effect of spin-orbit coupling on the topological phase diagram of a Shiba chain
NASA Astrophysics Data System (ADS)
Zhang, Junhua; Kim, Younghyun; Lutchyn, Roman; Rossi, E.
2015-03-01
Recently chains of magnetic adatoms placed on the surface of a superconductor with strong spin-orbit coupling have emerged as very promising systems for the realization of Majorana modes. In a recent work we have found that the presence of spin-orbit coupling can qualitatively modify the spectrum of the impurity-bound states, Yu-Shiba-Rusinov states, induced by a single magnetic impurity placed on a superconductor, when higher angular momentum components of the impurity potential are taken into account. Motivated by these results, we study in detail the effect of spin-orbit coupling on the electronic spectrum of a chain of Yu-Shiba-Rusinov states created by magnetic adatoms placed on the surface of a superconductor. In particular, we study the effect of the spin orbit coupling on the topological phase diagram of a chain of Yu-Shiba-Rusinov states. We acknowledge support from ONR-N00014-13-1-0321.
Phase Diagram of a Three-Orbital Model for High-Tc Cuprate Superconductors
NASA Astrophysics Data System (ADS)
Weber, Cédric; Giamarchi, T.; Varma, C. M.
2014-03-01
We study the phase diagram of an effective three-orbital model of the cuprates using variational Monte Carlo calculations on asymptotically large lattices and exact diagonalization on a 24-site cluster. States with ordered orbital current loops (LC), itinerant antiferromagnetism, d-wave superconductivity, and the Fermi liquid are investigated using appropriate Slater determinants refined by Jastrow functions for on-site and intersite correlations. We find an LC state stable in the thermodynamic limit for a range of parameters compatible with the Fermi surface of a typical hole doped superconductor provided the transfer integrals between the oxygen atoms have signs determined by the effects of indirect transfer through the Cu-4s orbitals as suggested by Andersen. The results of the calculations are that the LC phase gives way at lower dopings to an antiferromagnetism phase, and at larger dopings to superconductivity and Fermi liquid phases.
Laser induced electron diffraction: a tool for molecular orbital imaging
Paris-Sud XI, Université de
Laser induced electron diffraction: a tool for molecular orbital imaging M. Peters,1, 2 T. T of the initial molecular orbital from which the ionized electron is produced. We show that it is possible-field atomic or molecular ion- ization by an optical field, a free electronic wave packet is formed each time
Phase diagram of strongly attractive p-orbital fermions on optical lattices
NASA Astrophysics Data System (ADS)
De Silva, Theja N.
2015-10-01
We examine a system of doubly degenerate p-orbital polarized fermions on a two-dimensional square lattice with a strong on-site interaction. We consider the system density at the half filling limit and tackle the strong attractive interaction using a perturbation theory. We treat the four-site square plaquette interaction term generated from the directional tunneling dependence of p-orbitals using the fourth order in perturbation theory. We map the strong coupling particle Hamiltonian into an effective spin-Hamiltonian and then use a variational mean field approach and a linear spin-wave theory to study the phase diagram. Further, we discuss the experimental signatures of these phases within the context of current cold-atom experimental techniques.
NASA Astrophysics Data System (ADS)
Huang, Li; Du, Liang; Dai, Xi
2012-07-01
Motivated by the unexplored complexity of the phase diagrams for multiorbital Hubbard models, a three-band Hubbard model at integer fillings (N=4) with orbital degeneracy lifted partially by crystal field splitting is analyzed systematically in this work. By using the single-site dynamical mean-field theory and rotationally invariant Gutzwiller approximation, we have computed the full phase diagram with Coulomb interaction strength U and crystal field splitting ?. We find a large region in the phase diagram where an orbital-selective Mott phase will be stabilized by the positive crystal field lifting the orbital degeneracy. Further analysis indicates that Hund's rule coupling is essential for the orbital-selective Mott phase, and the transition toward this phase is accompanied by a high-spin to low-spin transition. Such a model may be relevant for the recently discovered Ru-based materials.
ERIC Educational Resources Information Center
Tsaparlis, Georgios
1997-01-01
Investigates the impact an undergraduate quantum chemistry course has on students' knowledge and understanding of atomic orbitals, molecular orbitals, and related concepts. Analysis reveals that students do not have a clear understanding of these concepts and confuse the various atomic orbital representations. Includes some suggestions and…
Tomographic Imaging of Molecular Orbitals in Length and Velocity Form
Lein, Manfred
in a single-active electron approximation [11]. Both observations support the idea of extending the techniqueTomographic Imaging of Molecular Orbitals in Length and Velocity Form Elmar V. van der ZwanGermany Abstract. Recently Itatani et al. [Nature 432, 876 (2004)] introduced the new concept of molecular orbital
Molecular-orbital model for metal-sapphire interfacial strength
NASA Technical Reports Server (NTRS)
Johnson, K. H.; Pepper, S. V.
1982-01-01
Self-consistent-field X-Alpha scattered-wave cluster molecular-orbital models have been constructed for transition and noble metals (Fe, Ni, Cu, and Ag) in contact with a sapphire (Al2O3) surface. It is found that a chemical bond is established between the metal d-orbital electrons and the nonbonding 2p-orbital electrons of the oxygen anions on the Al2O3 surface. An increasing number of occupied metal-sapphire antibonding molecular orbitals explains qualitatively the observed decrease of contact shear strength through the series Fe, Ni, Cu, and Ag.
Orbital Energy Levels in Molecular Hydrogen. A Simple Approach.
ERIC Educational Resources Information Center
Willis, Christopher J.
1988-01-01
Described are the energetics involved in the formation of molecular hydrogen using concepts that should be familiar to students beginning the study of molecular orbital theory. Emphasized are experimental data on ionization energies. Included are two-electron atomic and molecular systems. (CW)
Scanning Reactive Pathways with Orbital Biased Molecular Dynamics
Guidoni, Leonardo
Scanning Reactive Pathways with Orbital Biased Molecular Dynamics Leonardo Guidoni and Ursula system. This electronic reaction coordinate, which is expressed in terms of a penalty function of the one-electron orbital energies, has been applied to study different reaction pathways of s-cis-butadiene. Three
Strong-Field Molecular Ionization from Multiple Orbitals
Kotur, Marija; Weinacht, Thomas C.; Zhou, Congyi; Matsika, Spiridoula
2011-11-28
We demonstrate strong-field ionization from multiple orbitals of excited-state uracil molecules. The molecules are excited to the first bright state by an ultrafast laser pulse in the deep ultraviolet and then ionized with a strong-field laser pulse in the near infrared during ultrafast relaxation back down to the ground state. We measure time- and angle-dependent ion yields for multiple fragments created by strongfield ionization, and interpret the temporally and angularly resolved yields via ab initio electronic structure calculations. We find that the angular distribution for the electron removed from the lowest unoccupied molecular orbital follows the symmetry of the molecular orbital, whereas ionization of the molecule by removing electrons from deeper bound orbitals is more complicated.
NASA Astrophysics Data System (ADS)
Aftalion, Amandine; Mason, Peter
2013-08-01
We provide complete phase diagrams describing the ground state of a trapped spinor Bose-Einstein condensate under the combined effects of rotation and a Rashba spin-orbit coupling. The interplay between the different parameters (magnitude of rotation, strength of the spin-orbit coupling, and interaction) leads to a rich ground-state physics that we classify. We explain some features analytically in the Thomas-Fermi approximation, writing the problem in terms of the total density, total phase, and spin. In particular, we analyze the giant skyrmion and find that it is of degree 1 in the strong-segregation case. In some regions of the phase diagrams, we relate the patterns to a ferromagnetic energy.
Nonorthogonal molecular orbital method: Single-determinant theory
NASA Astrophysics Data System (ADS)
Watanabe, Yoshihiro; Matsuoka, Osamu
2014-05-01
Using the variational principle, we have derived a variant of the Adams-Gilbert equation for nonorthogonal orbitals of a single-determinant wave function, which we name the modified Adams-Gilbert equation. If we divide the molecular system into several subsystems, such as bonds, lone pairs, and residues, we can solve the equations for the subsystems one by one. Thus, this procedure has linear scaling. We have presented a practical procedure for solving the equations that is also applicable to macromolecular calculations. The numerical examples show that the procedure yields, with reasonable effort, results comparable with those of the Hartree-Fock-Roothaan method for orthogonal orbitals. To resolve the convergence difficulty in the self-consistent-field iterations, we have found that virtual molecular-orbital shifts are very effective.
SEMIEMPIRICAL MOLECULAR ORBITAL CALCULATIONS OF BAND GAPS OF CONJUGATED POLYMERS
Goddard III, William A.
SEMIEMPIRICAL MOLECULAR ORBITAL CALCULATIONS OF BAND GAPS OF CONJUGATED POLYMERS Tahir Cagin Research and Development Center, Materials Labarotory, Polymer Branch, Wright Patterson AFB, Ohio 45433 geometries and energy band gaps of conjugated polymers. In this study, we used a modified version of semi
Super Atomic Molecular Orbitals of Variably Protonated Symmetric Molecules
NASA Astrophysics Data System (ADS)
Latta, Tanner; Drake, Kyle; Zhang, G. P.
2015-03-01
The molecular structure of symmetric molecules creates conducive conditions for delocalized orbitals. The ? bonding delocalizes the valence electrons away from the individual molecules. These delocalized valence electrons allow the symmetric molecules to adapt the characteristics analogous to that of an individual atom, creating Super Atomic Molecular Orbitals, SAMOs. The symmetric molecule is then comparable to that of an individual atom with its regular atomic orbitals. When these symmetric molecules are protonated in any form, there are notable changes in the shapes of the Super Atomic Molecular Orbitals. We use the Density Functional Theory with a grid mesh method to compute the wavefunctions of those SAMOs. Then we examine the Rydberg States of these symmetric molecules through the calculated Eigenstates, and find an important trend in the filling of the SAMOs as well as relationships between variably protonated symmetric molecules. This is potentially very useful to understanding the photovoltaic effect in the fullerene- based solar cells. Support by U.S. Department of Energy No DE-FG02-06ER46304.
A Simple Demonstration of Atomic and Molecular Orbitals Using Circular Magnets
ERIC Educational Resources Information Center
Chakraborty, Maharudra; Mukhopadhyay, Subrata; Das, Ranendu Sekhar
2014-01-01
A quite simple and inexpensive technique is described here to represent the approximate shapes of atomic orbitals and the molecular orbitals formed by them following the principles of the linear combination of atomic orbitals (LCAO) method. Molecular orbitals of a few simple molecules can also be pictorially represented. Instructors can employ the…
BetaVoid: molecular voids via beta-complexes and Voronoi diagrams.
Kim, Jae-Kwan; Cho, Youngsong; Laskowski, Roman A; Ryu, Seong Eon; Sugihara, Kokichi; Kim, Deok-Soo
2014-09-01
Molecular external structure is important for molecular function, with voids on the surface and interior being one of the most important features. Hence, recognition of molecular voids and accurate computation of their geometrical properties, such as volume, area and topology, are crucial, yet most popular algorithms are based on the crude use of sampling points and thus are approximations even with a significant amount of computation. In this article, we propose an analytic approach to the problem using the Voronoi diagram of atoms and the beta-complex. The correctness and efficiency of the proposed algorithm is mathematically proved and experimentally verified. The benchmark test clearly shows the superiority of BetaVoid to two popular programs: VOIDOO and CASTp. The proposed algorithm is implemented in the BetaVoid program which is freely available at the Voronoi Diagram Research Center (http://voronoi.hanyang.ac.kr). PMID:24677176
Baldea, Ioan
2015-01-01
Estimating the relative alignment between the frontier molecular orbitals that dominates the charge transport through single-molecule junctions represents a challenge for theory. This requires approaches beyond the widely employed framework provided by the density functional theory, wherein the Kohn-Sham "orbitals" are treated as if they were real molecular orbitals, which is not the case. In this paper, we report results obtained by means of quantum chemical calculations, including the EOM-CCSD (equation-of-motion coupled-cluster singles and doubles), which is the state-of-the-art of quantum chemistry for medium-size molecules like those considered here. These theoretical results are validated against data on the molecular orbital energy offset relative to the electrodes' Fermi energy extracted from experiments for junctions based on 4,4'-bipyridine and 1,4-dicyanobenzene.
Imaging the symmetry breaking of molecular orbitals in carbon nanotubes H. Lin,1, 2
Paris-Sud XI, Université de
electronics applications. The molecular orbitals of nanotubes are of particular importance as they govern experimental investigation of molecular orbitals of single wall carbon nanotubes using atomically resolvedImaging the symmetry breaking of molecular orbitals in carbon nanotubes H. Lin,1, 2 J. Lagoute,1 V
Intracellular molecular distributions in spacecraft experiments in orbit around Earth
NASA Astrophysics Data System (ADS)
Haranas, Ioannis; Gkigkitzis, Ioannis; Zouganelis, George D.
2012-04-01
It is possible that the nucleolous inside the cell plays the role of a "gravity receptor". Furthermore, cells up to 10 ?m in diameter can demonstrate some effect due to the redistribution of mitochondria or nucleolous. Effects of gravity should be present in various cell systems where larger objects such as the ribosomes move from cell to cell. In this paper we study the effects of gravity on cells. In particular, we examine the resulting intracellular molecular distribution due to Brownian motion and the ordered distribution of molecules under the action of gravity, where n0 is the number per unit volume at certain level, and n is the number per unit volume above that level. This is an experiment that takes place at a certain orbital altitude in a spacecraft in orbit around Earth, where the acceleration due to the central field is corrected for the oblateness and also the rotation of the Earth. We found that equatorial circular and elliptical orbits have the highest n/n0 ratios. This experiment takes place in circular and elliptical orbits, with eccentricities e = 0, 0.1 and involves a bacterial cell at an orbital altitude of 300 km. We found that n/n0 = 1.00299 and 1.0037 respectively, which is still a 0.6-0.7 % higher than n/n0 = 0.0996685 calculated on the surface of the Earth. Examining mitochondria in similar orbital experiments we found that equatorial orbits result to higher n/n0 ratios. In particular, we found that n/n0 = 8.38119, where an elliptical orbit of eccentricity e = 0.1 results to n/n0 = 13.8525. Both are high above 100%, signifying the importance of Brownian motion over gravity. Our results are of interest to biomedical applications. Molecular concentrations are important for various processes such as the embryogenesis, positional homeostasis and its relation to cell energy expenditure, cell torque, cell deformation, and more. These results indicate that statistical molecular distributions play an important role for the recognition of a particular environment by the cell, in biological space experiment to come.
Laser induced electron diffraction: a tool for molecular orbital imaging
Michel Peters; Tung Nguyen-Dang; Eric Charron; Arne Keller; Osman Atabek
2012-03-18
We explore the laser-induced ionization dynamics of N2 and CO2 molecules subjected to a few-cycle, linearly polarized, 800\\,nm laser pulse using effective two-dimensional single active electron time-dependent quantum simulations. We show that the electron recollision process taking place after an initial tunnel ionization stage results in quantum interference patterns in the energy resolved photo-electron signals. If the molecule is initially aligned perpendicular to the field polarization, the position and relative heights of the associated fringes can be related to the molecular geometrical and orbital structure, using a simple inversion algorithm which takes into account the symmetry of the initial molecular orbital from which the ionized electron is produced. We show that it is possible to extract inter-atomic distances in the molecule from an averaged photon-electron signal with an accuracy of a few percents.
Characterization of molecular orbitals by counting nodal regions.
Hatano, Yasuyo; Yamamoto, Shigeyoshi; Tatewaki, Hiroshi
2005-03-01
The number of nodal regions can be used as an index for characterizing molecular orbitals. A computer program has been developed to count the number of nodal regions, based on the labeling and contraction algorithms. This program is applied to the water molecule, the hydrogen sulfide molecule, the hydrogen atomic orbitals, the Rydberg excited states of ethylene, dissociation of carbon monoxide, and CASSCF calculations of formaldehyde. Because the number of nodal regions is independent of the coordinate system, the method is applicable even when the molecular structure changes drastically as in bond rotation or bond elongation. Changes of nodal regions with bond elongation are investigated for carbon monoxide. A prescription for problems arising with basis set expansion techniques is also given. PMID:15641122
Emulating Molecular Orbitals and Electronic Dynamics with Ultracold Atoms
NASA Astrophysics Data System (ADS)
Lühmann, Dirk-Sören; Weitenberg, Christof; Sengstock, Klaus
2015-07-01
In recent years, ultracold atoms in optical lattices have proven their great value as quantum simulators for studying strongly correlated phases and complex phenomena in solid-state systems. Here, we reveal their potential as quantum simulators for molecular physics and propose a technique to image the three-dimensional molecular orbitals with high resolution. The outstanding tunability of ultracold atoms in terms of potential and interaction offer fully adjustable model systems for gaining deep insight into the electronic structure of molecules. We study the orbitals of an artificial benzene molecule and discuss the effect of tunable interactions in its conjugated ? electron system with special regard to localization and spin order. The dynamical time scales of ultracold atom simulators are on the order of milliseconds, which allows for the time-resolved monitoring of a broad range of dynamical processes. As an example, we compute the hole dynamics in the conjugated ? system of the artificial benzene molecule.
Low earth orbit molecular beam space simulation facility
Cross, J.B.
1984-01-01
A brief synopsis of the low earth orbit (LEO) satellite environment is presented including neutral and ionic species. Two ground based atomic and molecular beam instruments are described which are capable of simulating the interaction of space craft surfaces with the LEO environment and detecting the results of these interactions. The first detects mass spectrometrically low level fluxes of reactively and nonreactively surface scattered species as a function of scattering angle and velocity while the second UHV molecular beam, laser induced fluorescence apparatus is capable of measuring chemiluminescence produced by either gas phase or gas-surface interactions. A number of proposed experiments will be described.
Hydrogen outgassing considerations for an orbiting aluminum molecular shield
NASA Technical Reports Server (NTRS)
Outlaw, R. A.
1982-01-01
A molecular shield and associated hardware made of pure aluminum is shown to have an outgassing rate sufficiently low so that operations in orbit would undergo less density contributions than that present from the upper atmospheric atomic hydrogen contribution. Measurements of the atomic hydrogen outgassing from baked-out 6061 aluminum cylindrical samples 3 mm thick are demonstrated to be less than 1/100 trillion l/sec per sq cm, comparable to that of austenitic stainless steels. Calculations of the density distribution with a hemispherical molecular shield are presented, and the elimination of porosity in the aluminum shells is recommended by means of vacuum melting.
Molecular orbital engineering of single-molecular light emission
Daijiro Nozaki; Kazunari Yoshizawa
2004-01-01
A concept of single-molecular light emission is theoretically proposed by using a ?-conjugated molecule linked by meta-phenylene couplers, gold as the anode, and calcium as the cathode. The molecule, which comprises perylene at the center as the light-emitting moiety and two phenylacetylenes as the hole- and electron-transporting moieties, is designed to have localized ?-MOs with an appropriate energy gradient to
alpha-clustering and molecular-orbital states in sd-shell nuclei
Kimura, M. [Creative Research Institution Sousei Research Department, Hokkaido University, Sapporo 011-0021 (Japan); Furutachi, N. [Meme Media Laboratory, Hokkaido University, Sapporo 060-8628 (Japan)
2010-05-12
The alpha-clustering and molecular-orbitals of {sup 22}Ne and F isotopes are investigated based on antisymmetrized molecular dynamics (AMD). The observed candidates for the alpha cluster state of {sup 22}Ne are understood as the molecular-orbital states and alpha+{sup 18}O di-nuclei states. The presence of the molecular-orbital states in the O and F isotopes and the drastic reduction of their excitation energy near the neutron-drip line are predicted.
Simons, Jack
Chapter 7 The Most Elementary Molecular Orbital Models Contain Symmetry, Nodal Pattern, and Approximate Energy Information I. The LCAO-MO Expansion and the Orbital-Level Schrödinger Equation In the simplest picture of chemical bonding, the valence molecular orbitals i are constructed as linear
Sulfur at nickel-alumina interfaces - Molecular orbital theory
NASA Technical Reports Server (NTRS)
Hong, S. Y.; Anderson, Alfred B.; Smialek, James L.
1990-01-01
Previous studies on Al-Ni alloys containing sulfur as an impurity suggest that, when S is in the interface between a metal and an oxide scale, it weakens the chemical bonding between them. This paper investigates factors responsible for this effect, using a molecular orbital theory to predict sulfur structures and electronic properties on the Ni-Al2O3 interface. It is shown that, in absence of S, the basal plane of Al2O3 will bind strongly through the Al(3+) cation surface to Ni (111). When segregated S impurity is present on the Ni surface, there are too few interfacial AlS bonds to effect good adhesion, leading to an inhibition of the oxide scale adhesion in NiCrAl alloys.
Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors
Z. C. Tu
2013-02-08
The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency ($>1/2$) for a small load distribution factor ($<0.1$).
Ab initio molecular simulations with numeric atom-centered orbitals
NASA Astrophysics Data System (ADS)
Blum, Volker; Gehrke, Ralf; Hanke, Felix; Havu, Paula; Havu, Ville; Ren, Xinguo; Reuter, Karsten; Scheffler, Matthias
2009-11-01
We describe a complete set of algorithms for ab initio molecular simulations based on numerically tabulated atom-centered orbitals (NAOs) to capture a wide range of molecular and materials properties from quantum-mechanical first principles. The full algorithmic framework described here is embodied in the Fritz Haber Institute "ab initio molecular simulations" (FHI-aims) computer program package. Its comprehensive description should be relevant to any other first-principles implementation based on NAOs. The focus here is on density-functional theory (DFT) in the local and semilocal (generalized gradient) approximations, but an extension to hybrid functionals, Hartree-Fock theory, and MP2/GW electron self-energies for total energies and excited states is possible within the same underlying algorithms. An all-electron/full-potential treatment that is both computationally efficient and accurate is achieved for periodic and cluster geometries on equal footing, including relaxation and ab initio molecular dynamics. We demonstrate the construction of transferable, hierarchical basis sets, allowing the calculation to range from qualitative tight-binding like accuracy to meV-level total energy convergence with the basis set. Since all basis functions are strictly localized, the otherwise computationally dominant grid-based operations scale as O(N) with system size N. Together with a scalar-relativistic treatment, the basis sets provide access to all elements from light to heavy. Both low-communication parallelization of all real-space grid based algorithms and a ScaLapack-based, customized handling of the linear algebra for all matrix operations are possible, guaranteeing efficient scaling (CPU time and memory) up to massively parallel computer systems with thousands of CPUs.
PUBLISHED ONLINE: 26 JUNE 2011 | DOI: 10.1038/NPHYS2029 Generalized molecular orbital tomography
Loss, Daniel
ARTICLES PUBLISHED ONLINE: 26 JUNE 2011 | DOI: 10.1038/NPHYS2029 Generalized molecular orbital generating medium, which inspired vigorous efforts to tomographically image the valence orbital of atoms and molecules. The orbital retrieval is nevertheless seriously hindered by the complexity of the harmonic
Band Formation in a Molecular Quantum Well via 2D Superatom Orbital Interactions
Dougherty, D. B.; Feng, Min; Petek, Hrvoje; Yates, John T.; Zhao, Jin
2012-12-28
By scanning tunneling microscopy and spectroscopy, we study nearly free electron band formation of the ?*lowest unoccupied molecular orbital of C?F? on a Cu(111) surface. In fractal islands, the lowest unoccupied molecular orbital energy systematically stabilizes with the number of interacting near-neighbor C?F? molecules. Density functional theory calculations reveal the origin of effective intermo- lecular orbital overlap in the previously unrecognized superatom character of the ?*orbital of ?F? molecules. The discovery of superatom orbitals in planar molecules offers a new universal principle for effective band formation, which can be exploited in designing organic semiconductors with nearly free electron properties
Analyzing and Interpreting NMR Spin-Spin Coupling Constants Using Molecular Orbital Calculations
ERIC Educational Resources Information Center
Autschbach, Jochen; Le Guennic, Boris
2007-01-01
Molecular orbital plots are used to analyze and interpret NMR spin-spin coupling constants, also known as J coupling constants. Students have accepted the concept of contributions to molecular properties from individual orbitals without the requirement to provide explicit equations.
An Introduction to Hartree-Fock Molecular Orbital C. David Sherrill
Sherrill, David
to much of electronic structure theory. It is the basis of molecular orbital (MO) theory, which posits that each electron's motion can be described by a single-particle function (orbital) which does not depend is that the electronic wavefunction (r; R) contains lots of useful information about molecular properties such as dipole
NASA Astrophysics Data System (ADS)
Abramo, M. C.; Caccamo, C.; Costa, D.; Munaò, G.
2014-09-01
We report an atomistic molecular dynamics determination of the phase diagram of a rigid-cage model of C36. We first show that free energies obtained via thermodynamic integrations along isotherms displaying "van der Waals loops," are fully reproduced by those obtained via isothermal-isochoric integration encompassing only stable states. We find that a similar result also holds for isochoric paths crossing van der Waals regions of the isotherms, and for integrations extending to rather high densities where liquid-solid coexistence can be expected to occur. On such a basis we are able to map the whole phase diagram of C36, with resulting triple point and critical temperatures about 1770 K and 2370 K, respectively. We thus predict a 600 K window of existence of a stable liquid phase. Also, at the triple point density, we find that the structural functions and the diffusion coefficient maintain a liquid-like character down to 1400-1300 K, this indicating a wide region of possible supercooling. We discuss why all these features might render possible the observation of the melting of C36 fullerite and of its liquid state, at variance with what previously experienced for C60.
Nakata, Hiroya [Tokyo Institute of Technology; Schmidt, Michael W [Ames Laboratory; Fedorov, Dmitri G [National Institute of Advanced Industrial Science and Technology (AIST); Kitaura, Kazuo [Kobe University; Nakamura, Shinichiro [Nakamura Lab; Gordon, Mark S [Ames Laboratory
2014-10-16
The fully analytic energy gradient has been developed and implemented for the restricted open-shell Hartree–Fock (ROHF) method based on the fragment molecular orbital (FMO) theory for systems that have multiple open-shell molecules. The accuracy of the analytic ROHF energy gradient is compared with the corresponding numerical gradient, illustrating the accuracy of the analytic gradient. The ROHF analytic gradient is used to perform molecular dynamics simulations of an unusual open-shell system, liquid oxygen, and mixtures of oxygen and nitrogen. These molecular dynamics simulations provide some insight about how triplet oxygen molecules interact with each other. Timings reveal that the method can calculate the energy gradient for a system containing 4000 atoms in only 6 h. Therefore, it is concluded that the FMO-ROHF method will be useful for investigating systems with multiple open shells.
Goddard III, William A.
Phase diagram of MgO from density-functional theory and molecular-dynamics simulations Alejandro use first-principles methods no empirical parameters to establish the phase diagram for the B1 Na curves of the B1-B2 and B1-liquid phases. This leads to a first-principles phase diagram for Mg
Khaliullin, Rustam Z.; Head-Gordon, Martin [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Bell, Alexis T. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)
2008-05-14
A new method based on absolutely localized molecular orbitals (ALMOs) is proposed to measure the degree of intermolecular electron density delocalization (charge transfer) in molecular complexes. ALMO charge transfer analysis (CTA) enables separation of the forward and backward charge transfer components for each pair of molecules in the system. The key feature of ALMO CTA is that all charge transfer terms have corresponding well defined energetic effects that measure the contribution of the given term to the overall energetic stabilization of the system. To simplify analysis of charge transfer effects, the concept of chemically significant complementary occupied-virtual orbital pairs (COVPs) is introduced. COVPs provide a simple description of intermolecular electron transfer effects in terms of just a few localized orbitals. ALMO CTA is applied to understand fundamental aspects of donor-acceptor interactions in borane adducts, synergic bonding in classical and nonclassical metal carbonyls, and multiple intermolecular hydrogen bonds in a complex of isocyanuric acid and melamine. These examples show that the ALMO CTA results are generally consistent with the existing conceptual description of intermolecular bonding. The results also show that charge transfer and the energy lowering due to charge transfer are not proportional to each other, and some interesting differences emerge which are discussed. Additionally, according to ALMO CTA, the amount of electron density transferred between molecules is significantly smaller than charge transfer estimated from various population analysis methods.
Orbital-Free Molecular Dynamics Simulations at Extreme Conditions
NASA Astrophysics Data System (ADS)
Kress, J. D.; Collins, L. A.; Ticknor, C.
2015-06-01
Large-scale molecular dynamics (MD) simulations in an orbital-free (OF) density-functional theory (DFT) formulation have been performed for pure and mixed species over a broad range of temperatures (T) and densities (?) that includes the warm, dense matter and high-energy density physics regimes. A finite-temperature Thomas-Fermi-Dirac form with a local-density exchange-correlation potential and a regularized electron-ion interaction represents the quantum nature of the electrons. In particular, we examine the efficacy of the OFMD approach as an effective bridge between Kohn-Sham DFT MD at low temperatures and simple, fully-ionized plasma models at high temperatures. Comparisons against intermediate-range constructions such as the Yukawa and one-component plasmas are also made. We examine the mass transport (diffusion, viscosity) properties of various systems, ranging from light to heavy elements, including lithium hydride (LiH), mixtures of LiH with uranium, mixtures of deuterium-tritium (DT) with plutonium and mixtures of DT with plastic (CH). The OFMD mass transport results have been fitted to simple functions of ? and T suitable for use in hydrodynamics simulation codes.
Molecular structures of carotenoids as predicted by MNDO-AM1 molecular orbital calculations
NASA Astrophysics Data System (ADS)
Hashimoto, Hideki; Yoda, Takeshi; Kobayashi, Takayoshi; Young, Andrew J.
2002-02-01
Semi-empirical molecular orbital calculations using AM1 Hamiltonian (MNDO-AM1 method) were performed for a number of biologically important carotenoid molecules, namely all- trans-?-carotene, all- trans-zeaxanthin, and all- trans-violaxanthin (found in higher plants and algae) together with all- trans-canthaxanthin, all- trans-astaxanthin, and all- trans-tunaxanthin in order to predict their stable structures. The molecular structures of all- trans-?-carotene, all- trans-canthaxanthin, and all- trans-astaxanthin predicted based on molecular orbital calculations were compared with those determined by X-ray crystallography. Predicted bond lengths, bond angles, and dihedral angles showed an excellent agreement with those determined experimentally, a fact that validated the present theoretical calculations. Comparison of the bond lengths, bond angles and dihedral angles of the most stable conformer among all the carotenoid molecules showed that the displacements are localized around the substituent groups and hence around the cyclohexene rings. The most stable conformers of all- trans-zeaxanthin and all- trans-violaxanthin gave rise to a torsion angle around the C6-C7 bond to be ±48.7 and -84.8°, respectively. This difference is a key factor in relation to the biological function of these two carotenoids in plants and algae (the xanthophyll cycle). Further analyses by calculating the atomic charges and using enpartment calculations (division of bond energies between component atoms) were performed to ascribe the cause of the different observed torsion angles.
Resolving Multiple Molecular Orbitals Using Two-Dimensional High-Harmonic Spectroscopy
NASA Astrophysics Data System (ADS)
Yun, Hyeok; Lee, Kyung-Min; Sung, Jae Hee; Kim, Kyung Taec; Kim, Hyung Taek; Nam, Chang Hee
2015-04-01
High-harmonic radiation emitted from molecules in a strong laser field contains information on molecular structure and dynamics. When multiple molecular orbitals participate in high-harmonic generation, resolving the contribution of each orbital is crucial for understanding molecular dynamics and for extending high-harmonic spectroscopy to more complicated molecules. We show that two-dimensional high-harmonic spectroscopy can resolve high-harmonic radiation emitted from the two highest-occupied molecular orbitals, HOMO and HOMO-1, of aligned molecules. By the application of an orthogonally polarized two-color laser field that consists of the fundamental and its second-harmonic fields to aligned CO2 molecules, the characteristics attributed to the two orbitals are found to be separately imprinted in odd and even harmonics. Two-dimensional high-harmonic spectroscopy may open a new route to investigate ultrafast molecular dynamics during chemical processes.
Moving Beyond the Single Center--Ways to Reinforce Molecular Orbital Theory in an Inorganic Course
ERIC Educational Resources Information Center
Cass, Marion E.; Hollingsworth, William E.
2004-01-01
It is suggested that molecular theory should be taught earlier in the inorganic chemistry curriculum even in the introductory chemistry course in order to integrate molecular orbital arguments more effectively throughout the curriculum. The method of teaching relies on having access to molecular modeling software as having access to such software…
Molecular integrals over the gauge-including atomic orbitals. II. The Breit-Pauli interaction.
Ishida, Kazuhiro
2003-11-30
Each accompanying coordinate expansion (ACE) formula is derived for each of the orbit-orbit interaction, the spin-orbit coupling, the spin-spin coupling, and the contact interaction integrals over the gauge-including atomic orbitals (GIAOs) by the use of the solid harmonic gradient (SHG) operator. Each ACE formula is the general formula derived at the first time for each of the above molecular integrals over GIAOs. These molecular integrals are arising in the Breit-Pauli two-electron interaction for a relativistic calculation. We may conclude that we can derive a certain ACE formula for any kind of molecular integral over solid harmonic Gaussian-type orbitals by using the SHG operator. The present ACE formulas will be useful, for example, for a calculation of a molecule in a uniform magnetic field, for a relativistic calculation, and so on, with the GIAO as a basis function. PMID:14515370
Morris-Sherwood, Betty Jeanne
1981-01-01
of the Robert A. Welch Foundation is gratefully acknowledged. CHAPTER TABLE OF CONTENTS PAGE I INTRODUCTION. PHOTOELECTRON SPECTRA AND MOLECULAR ORBITAL CALCULATIONS ON (nS-CYCLOPENTADIENYL) DINITROSYL- HALOCHROMIUM AND -TUNGSTEN. 3 Introduction... ORBITAL CALCULATIONS ON BIS(CYCLOPENTADIENYLDICARBONYL- CHROMIUM, MOLYBDENUM AND TUNGSTEN). . . . . . . . . . . . . . . Introduction Experimental and Theoretical Preparation. Spectroscopy. 12 12 16 17 18 18 19 20 27 27 28 28 28 TABLE...
R. F. Nalewajski
2006-01-01
The communication approach of Information Theory (IT) to chemical bonds is extended to cover the excited electron configurations within the standard orbital description of the molecular electronic structure. The non-projected AO-promotion channels for excited electronic states, involving probability scattering via the configuration occupied molecular orbitals, do not reflect the bond-order reduction upon electron excitation from the ground-state. The superposition principle
NASA Astrophysics Data System (ADS)
Balachandran, Janakiraman; Reddy, Pramod; Dunietz, Barry; Gavini, Vikram
2014-03-01
The frontier molecular orbital (FMO) reorganization and in turn on the thermopower of the aromatic molecules trapped between metal electrodes (aka molecular junctions) depends on two effects namely (1) the stabilization effect - due to the physical presence of the metal electrode atoms and (2) change in e-e interactions - due to end-group mediated charge transfer. The stabilization effect always reduces the FMO energies. The charge transfer effect increases the FMO energies in charge-gaining molecules, which in turn opposes the stabilization effect resulting in a small overall shift. However, the charge transfer effect decreases the FMO energies in charge-losing molecules, which in turn complements the stabilization effect resulting in a large overall downward shift. This hypothesis is validated by delineating the shifts due to stabilization and charge-transfer effects independently. Further we also demonstrate the generality of the hypothesis by applying it on a wide range of aromatic molecules with different length and end-groups. Finally, we also present computationally efficient strategies, based on the proposed mechanism, to quantitatively compute the FMO reorganization which in turn has potential for high throughput analysis of molecular junctions.
Tomographic imaging of asymmetric molecular orbitals with a two-color multicycle laser field.
Qin, Meiyan; Zhu, Xiaosong; Zhang, Qingbin; Lu, Peixiang
2012-12-15
We theoretically demonstrate a scheme for tomographic reconstruction of asymmetric molecular orbitals based on high-order harmonic generation with a two-color multicycle laser field. It is shown that by adjusting the relative phase of the two fields, the returning electrons can be forced to recollide from one direction for all the orientations of molecules. Thus, the reconstruction of the asymmetric orbitals can be carried out with multicycle laser field. This releases the stringent requirement of a single-cycle pulse with a stabilized and controllable carrier-envelope phase for the tomographic imaging of asymmetric molecular orbitals. PMID:23258054
Gao, Hongjun
) Communication: Superatom molecular orbitals: New types of long-lived electronic states J. Chem. Phys. 135 the intrinsic electronic structures of molecular adsorbates and their interactions. VC 2011 American InstituteDirect imaging of intrinsic molecular orbitals using two-dimensional, epitaxially
Mechanically controlled molecular orbital alignment in single molecule junctions
Christopher Bruot; Joshua Hihath; Nongjian Tao
2011-01-01
Research in molecular electronics often involves the demonstration of devices that are analogous to conventional semiconductor devices, such as transistors and diodes, but it is also possible to perform experiments that have no parallels in conventional electronics. For example, by applying a mechanical force to a molecule bridged between two electrodes, a device known as a molecular junction, it is
Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures
Drummond, N. D.; Monserrat, Bartomeu; Lloyd-Williams, Jonathan H.; López Ríos, P.; Pickard, Chris J.; Needs, R. J.
2015-01-01
advanced theoretical methods (diffusion quantum Monte Carlo calculations) find the metallic structure to be uncompetitive, and predict a phase diagram in reasonable agreement with experiment. This greatly strengthens the claim that the candidate atomic...
Liu, Xiaojing; Sun, Xin; Xu, Xijin; Sun, Ping
2015-11-01
By using atomic force microscopy, birth and spread has proved to be the primary growth mechanism for l-prolinium phosphate (LPP). The phenomenon of newly formed islands expanding to the edge of the preceding terrace was observed. The optimized molecular structure and the molecular properties were calculated by density functional theory method. Natural bond orbital analysis was carried out to demonstrate the various inter and intramolecular interactions that are responsible for the stabilization of LPP leading to high NLO activity. Molecular electrostatic potential, frontier molecular orbital analysis and thermodynamic properties were investigated to get a better insight of the molecular properties. Global and local reactivity descriptors were computed to predict the reactivity and reactive sites on the molecules. Non-linear optical (NLO) properties such as the total dipole moment (?) and first order hyperopolarizability (?) were also calculated to predict NLO behavior. PMID:26067937
Hilgeroth, Andreas; Molnár, Annamária; Molnár, Josef; Voigt, Burkhardt
2006-04-01
Molecular orbital energies of energetically minimized series of extended aromatic and aminoalkyl side chain substituted phenothiazine compounds have been considered with respect to charge transfer (CT) binding properties to P-glycoprotein (P-gp) amino acids of the first P-gp loop. A dependency of decreasing energies of lowest unoccupied orbitals (E(lumo)) with reduced CT binding properties to an increasing P-gp mediated multidrug resistance (MDR) has been found for the extended aromatic compounds. PMID:16516350
Solution of multi-center molecular integrals of Slater-type orbitals
NASA Technical Reports Server (NTRS)
Tai, H.
1989-01-01
The troublesome multi-center molecular integrals of Slater-type orbitals (STO) in molecular physics calculations can be evaluated by using the Fourier transform and proper coupling of the two center exchange integrals. A numerical integration procedure is then readily rendered to the final expression in which the integrand consists of well known special functions of arguments containing the geometrical arrangement of the nuclear centers and the exponents of the atomic orbitals. A practical procedure was devised for the calculation of a general multi-center molecular integrals coupling arbitrary Slater-type orbitals. Symmetry relations and asymptotic conditions are discussed. Explicit expressions of three-center one-electron nuclear-attraction integrals and four-center two-electron repulsion integrals for STO of principal quantum number n=2 are listed. A few numerical results are given for the purpose of comparison.
M. Cao; A. P. Malanoski; J. W. Schroer; P. A. Monson
2005-01-01
We consider the problem of using molecular modeling and simulation in understanding trends in solid-fluid and solid-solid phase behavior of organic molecules as we change molecular structure. Our focus is on using molecular models that are simple enough to be studied over a wide range of conditions, but realistic enough to reveal important insights into the molecular level behavior. As
Detection of Molecular Hydrogen Orbiting a "Naked" T Tauri Star
Jeffrey S. Bary; David A. Weintraub; Joel H. Kastner
2002-07-29
Astronomers have established that for a few million years newborn stars possess disks of orbiting gas and dust. Such disks, which are likely sites of planet formation, appear to disappear once these stars reach ages of 5-10 times 10^6 yr; yet, >= 10^7 yr is thought necessary for giant planet formation. If disks dissipate in less time than is needed for giant planet formation, such planets may be rare and those known around nearby stars would be anomalies. Herein, we report the discovery of H_2 gas orbiting a weak-lined T Tauri star heretofore presumed nearly devoid of circumstellar material. We estimate that a significant amount of H_2 persists in the gas phase, but only a tiny fraction of this mass emits in the near-infrared. We propose that this star possesses an evolved disk that has escaped detection thus far because much of the dust has coagulated into planetesimals. This discovery suggests that the theory that disks are largely absent around such stars should be reconsidered. The widespread presence of such disks would indicate that planetesimals can form quickly and giant planet formation can proceed to completion before the gas in circumstellar disks disperses.
Molecular orbital ordering in titania and the associated semiconducting behavior
Park, Joseph; Ok, Kyung-Chul; Park, Jin-Seong; Du Ahn, Byung; Hun Lee, Je; Park, Jae-Woo; Chung, Kwun-Bum
2011-10-03
RF-sputtered TiO{sub x} layers were thermally treated and the associated thin-film transistor properties were studied. X-ray diffraction and x-ray absorption spectroscopy analyses indicate that as-grown amorphous TiO{sub x} films crystallize to anatase at temperatures above 450 deg. C in air. Thin-film transistors incorporating anatase active layers exhibit n-type behavior, with field effect mobility values near 0.11 cm{sup 2}/Vs when annealed at 550 deg. C. Such a phenomenon is suggested to originate from the ordering of Ti 3d orbitals upon crystallization, and the mobility enhancement at higher annealing temperatures may be attributed to the reduced grain boundary scattering of carriers by virtue of enlarged average grain size.
A growth diagram for plasma-assisted molecular beam epitaxy of GaN nanocolumns on Si(111)
Fernandez-Garrido, S.; Grandal, J.; Calleja, E.; Sanchez-Garcia, M. A.; Lopez-Romero, D.
2009-12-15
The morphology of GaN samples grown by plasma-assisted molecular beam epitaxy on Si(111) was systematically studied as a function of impinging Ga/N flux ratio and growth temperature (730-850 deg. C). Two different growth regimes were identified: compact and nanocolumnar. A growth diagram was established as a function of growth parameters, exhibiting the transition between growth regimes, and showing under which growth conditions GaN cannot be grown due to thermal decomposition and Ga desorption. Present results indicate that adatoms diffusion length and the actual Ga/N ratio on the growing surface are key factors to achieve nanocolumnar growth.
NASA Astrophysics Data System (ADS)
Cappellari, Michele; Emsellem, Eric; Bacon, R.; Bureau, M.; Davies, Roger L.; de Zeeuw, P. T.; Falcón-Barroso, Jesús; Krajnovi?, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; van den Bosch, Remco C. E.; van de Ven, Glenn
2007-08-01
We analyse the orbital distribution of elliptical (E) and lenticular (S0) galaxies using SAURON integral-field stellar kinematics within about one effective (half-light) radius. We construct the anisotropy diagram, which relates the ratio of the ordered and random motion in a galaxy (V/?) to its observed ellipticity (?), for the 48 E/S0 galaxies from the SAURON survey. For a subsample of 24 galaxies consistent with axisymmetry, we use three-integral axisymmetric Schwarzschild dynamical models to recover the detailed orbital distribution, and we find good agreement with the anisotropy derived from the (V/?, ?) diagram. In a companion paper (Paper IX), we show that the early-type galaxies can be subdivided into two classes of systems with or without a significant amount of specific stellar angular momentum. Here, we show that the two classes have different distributions on the (V/?, ?) diagram. The slow rotators are more common among the most massive systems and are generally classified as E from photometry alone. Those in our sample tend to be fairly round (? <~ 0.3), but can have significant kinematical misalignments, indicating that as a class they are moderately triaxial, and span a range of anisotropies (? <~ 0.3). The fast rotators are generally fainter and are classified as either E or S0. They can appear quite flattened (? <~ 0.7), do not show significant kinematical misalignments (unless barred or interacting), indicating they are nearly axisymmetric and span an even larger range of anisotropies (? <~ 0.5). These results are confirmed when we extend our analysis to 18 additional E/S0 galaxies observed with SAURON. The dynamical models indicate that the anisotropy inferred from the (V/?, ?) diagram is due to a flattening of the velocity ellipsoid in the meridional plane (?R > ?z), which we quantify with the ? anisotropy parameter. We find a trend of increasing ? for intrinsically flatter galaxies. A number of the fast rotators show evidence for containing a flattened, kinematically distinct component, which in some cases counter-rotates relative to the main galaxy body. These components are generally more metal rich than the galaxy body. All these results support the idea that fast rotators are nearly oblate and contain disc-like components. The role of gas must have been important for their formation. The slow rotators are weakly triaxial. Current collisionless merger models seem unable to explain their detailed observed properties.
Schlegel, H. Bernhard
Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Received June 6, 2000 The chemical vapor deposition (CVD) of titanium nitride can be carried out with TiCl4 materials and conductive coatings for microelectronics, and decorative coatings.1-3 Chemical vapor
Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation and
Schlegel, H. Bernhard
Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation- ization of Ti(NR2)2NH in the chemical vapor deposition (CVD) of titanium nitride films. This study uses, solar coatings for glass, and decorative coatings.1-4 For semiconductor applications, chemical vapor
Molecular orbital studies of titanium nitride chemical vapor deposition: gas phase b-elimination
Schlegel, H. Bernhard
Molecular orbital studies of titanium nitride chemical vapor deposition: gas phase b 48202, USA Received 7 November 2000; in ®nal form 27 March 2001 Abstract Chemical vapor deposition (CVD the use of chemical vapor deposition (CVD) to physical deposition when preparing Ti±N thin ®lms be- cause
Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Radical Reactions
Schlegel, H. Bernhard
Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Radical Reactions-phase reactions involved in the radical mechanism for zinc oxide chemical vapor deposition have been examined involve the thermal dissociation of diethyl zinc. The second bond dissociation of diethyl zinc
Schlegel, H. Bernhard
Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Hydrolysis of Diethyl Zinc, Elimination Reactions, and Formation of Dimers and Tetramers Stanley M. Smith and H. Bernhard deposition of zinc oxide thin films can be carried out with diethyl zinc and water vapor. The present study
Enantioselective Organo-Singly Occupied Molecular Orbital Catalysis: The Carbo-oxidation of Styrenes
MacMillan, David W. C.
Enantioselective Organo-Singly Occupied Molecular Orbital Catalysis: The Carbo for Catalysis at Princeton UniVersity, Princeton, New Jersey 08544 Received September 23, 2008; E-mail: dmacmill@princeton.edu A critical objective for the continued advancement of the field of asymmetric catalysis is the design
Lan Chen; Zhenpeng Hu; Aidi Zhao; Bing Wang; Yi Luo; Jinlong Yang; J. G. Hou
2007-01-01
A new mechanism for negative differential resistance (NDR) originating from local orbital symmetry matching between an electrode and a molecule in a single molecular electronic device is proposed and demonstrated by a joint experimental and theoretical scanning tunneling microscope study of a cobalt phthalocyanines (CoPc) molecule on a gold substrate. For two different metal tips used, Ni and W, NDR
Schlegel, H. Bernhard
FULL PAPER Synthesis, Structure, and Molecular Orbital Calculations of (Pyrazolato)vanadium,[a] Mary Jane Heeg,[a] H. Bernhard Schlegel,[a] and Charles H. Winter*[a] Keywords: Vanadium / Pyrazolato ligands / Ab initio calculations / N ligands / Coordination modes Treatment of trichlorotris(tetrahydrofuran)vanadium
MacMillan, David W. C.
) catalysis Anthony Mastracchio, Alexander A. Warkentin, Abbas M. Walji, and David W. C. MacMillan1 Merck Center for Catalysis at Princeton University, Princeton, NJ 08544 Edited by Eric N. Jacobsen, Harvard molecular orbital catalysis. Geometrically constrained radical cations, forged from the one
A semi-empirical molecular orbital study of freestanding and fullerene-encapsulated Mo nanoclusters
Elliott, James
A semi-empirical molecular orbital study of freestanding and fullerene-encapsulated Mo nanoclusters as implemented in the VAMP module of Materials Studiow , of both freestanding and fullerene by opening of hexagonhexagon (66) carbon bonds that lead eventually to a splitting open of the fullerene
Swihart, Mark T.
Thermochemistry of Aluminum Species for Combustion Modeling from Ab Initio Molecular Orbital initio methods for computational thermochemistry have been applied to aluminum compounds expected to be present during combustion of aluminum particles. The computed enthalpies of formation at 298.15 K agree
J. Meyer; W.-D. Sepp; B. Fricke; A. Rosén
1996-01-01
A revised and extended version of the program TSYM is presented. Relativistic symmetry-adapted basis systems for molecular calculations are constructed from atomic orbitals according to the LCAO method. The molecular symmetry group can be one of 45 finite double point groups. The algorithm based on the projection operator formalism automatically ensures the linear independence of the symmetry orbitals. Time reversal
Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures
Drummond, N. D.; Monserrat, Bartomeu; Lloyd-Williams, Jonathan H.; Ríos, P. López; Pickard, Chris J.; Needs, R. J.
2015-01-01
Establishing the phase diagram of hydrogen is a major challenge for experimental and theoretical physics. Experiment alone cannot establish the atomic structure of solid hydrogen at high pressure, because hydrogen scatters X-rays only weakly. Instead, our understanding of the atomic structure is largely based on density functional theory (DFT). By comparing Raman spectra for low-energy structures found in DFT searches with experimental spectra, candidate atomic structures have been identified for each experimentally observed phase. Unfortunately, DFT predicts a metallic structure to be energetically favoured at a broad range of pressures up to 400?GPa, where it is known experimentally that hydrogen is non-metallic. Here we show that more advanced theoretical methods (diffusion quantum Monte Carlo calculations) find the metallic structure to be uncompetitive, and predict a phase diagram in reasonable agreement with experiment. This greatly strengthens the claim that the candidate atomic structures accurately model the experimentally observed phases. PMID:26215251
Martay, Hugo E. L.; England, Duncan G.; McCabe, David J.; Walmsley, Ian A.
2011-04-15
The complexity of ultrafast molecular photoionization presents an obstacle to the modeling of pump-probe experiments. Here, a simple optimized model of atomic rubidium is combined with a molecular dynamics model to predict quantitatively the results of a pump-probe experiment in which long-range rubidium dimers are first excited, then ionized after a variable delay. The method is illustrated by the outline of two proposed feasible experiments and the calculation of their outcomes. Both of these proposals use Feshbach {sup 87}Rb{sub 2} molecules. We show that long-range molecular pump-probe experiments should observe spin-orbit precession given a suitable pump pulse, and that the associated high-frequency beat signal in the ionization probability decays after a few tens of picoseconds. If the molecule was to be excited to only a single fine-structure state, then a low-frequency oscillation in the internuclear separation would be detectable through the time-dependent ionization cross section, giving a mechanism that would enable observation of coherent vibrational motion in this molecule.
Finite-temperature orbital-free DFT molecular dynamics: Coupling PROFESS and QUANTUM ESPRESSO
NASA Astrophysics Data System (ADS)
Karasiev, Valentin V.; Sjostrom, Travis; Trickey, S. B.
2014-12-01
Implementation of orbital-free free-energy functionals in the PROFESS code and the coupling of PROFESS with the QUANTUM ESPRESSO code are described. The combination enables orbital-free DFT to drive ab initio molecular dynamics simulations on the same footing (algorithms, thermostats, convergence parameters, etc.) as for Kohn-Sham (KS) DFT. All the non-interacting free-energy functionals implemented are single-point: the local density approximation (LDA; also known as finite-T Thomas-Fermi, ftTF), the second-order gradient approximation (SGA or finite-T gradient-corrected TF), and our recently introduced finite-T generalized gradient approximations (ftGGA). Elimination of the KS orbital bottleneck via orbital-free methodology enables high-T simulations on ordinary computers, whereas those simulations would be costly or even prohibitively time-consuming for KS molecular dynamics (MD) on very high-performance computer systems. Example MD simulations on H over a temperature range 2000 K?T?4,000,000 K are reported, with timings on small clusters (16-128 cores) and even laptops. With respect to KS-driven calculations, the orbital-free calculations are between a few times through a few hundreds of times faster.
Ab initio molecular orbital study of the substituent effect on phosphine borane complexes
NASA Astrophysics Data System (ADS)
Anane, Hafid; Jarid, Abdellah; Boutalib, Abderrahim; Nebot-Gil, Ignacio; Tomás, Francisco
1998-11-01
Ab initio molecular orbital calculations have been used to study the substituent effect on H 3BPH nMe 3- n and Me 3- nH nBPH 3 ( n=0-3) phosphine-borane complexes. The ab initio results show that successive methyl substitution on the phosphine favours complex formation, contrary to successive methyl substitution on the borane. The natural bond orbitals partitioning scheme suggests that, in general, there is no correlation between the charge transfer and the complexation energies. It also shows the shortening of the P-H and P-C bond lengths, upon complexation, is due to the increasing `s' character of these bonds.
Petersen, Ingo; Henkel, Jost; Lein, Manfred
2015-03-13
Strong-field ionization of aligned diatomic and polyatomic molecules such as O2, N2, C2H4, and others in circularly polarized laser fields is investigated theoretically. By calculating the emission-angle-resolved lateral width of the momentum distribution perpendicular to the polarization plane, we show that nodal planes in molecular orbitals are directly imprinted on the angular dependence of the width. We demonstrate that orbital symmetries can be distinguished with the information obtained by observing the lateral width in addition to the angular distributions. PMID:25815929
Lühmann, Dirk-Sören; Sengstock, Klaus
2015-01-01
In the recent years, ultracold atoms in optical lattices have proven their great value as quantum simulators for studying strongly-correlated phases and complex phenomena in solid-state systems. Here we reveal their potential as quantum simulators for molecular physics and propose a technique to image the three-dimensional molecular orbitals with high resolution. The outstanding tunability of ultracold atoms in terms of potential and interaction offer fully-adjustable model systems for gaining deep insight into the electronic structure of molecules. We study the orbitals of an artificial benzene molecule and discuss the effect of tunable interactions in its conjugated pi electron system with special regard to localization and spin order. The dynamical timescale of ultracold atom simulators are on the order milliseconds which allow for the time-resolved monitoring of a broad range of dynamical processes. As an example, we compute the hole dynamics in the conjugated pi system of the artificial benzene molecule.
Use of an auxiliary basis set to describe the polarization in the fragment molecular orbital method
NASA Astrophysics Data System (ADS)
Fedorov, Dmitri G.; Kitaura, Kazuo
2014-03-01
We developed a dual basis approach within the fragment molecular orbital formalism enabling efficient and accurate use of large basis sets. The method was tested on water clusters and polypeptides and applied to perform geometry optimization of chignolin (PDB: 1UAO) in solution at the level of DFT/6-31++G??, obtaining a structure in agreement with experiment (RMSD of 0.4526 Å). The polarization in polypeptides is discussed with a comparison of the ?-helix and ?-strand.
Sherman, David M.
1986-01-01
A molecular orbital description, based on spin-unrestricted X??-scattered wave calculations, is given for the electronic structures of mixed valence iron oxides and silicates. The cluster calculations show that electron hopping and optical intervalence charge-transger result from weak FeFe bonding across shared edges of FeO6 coordination polyhedra. In agreement with Zener's double exchange model, FeFe bonding is found to stabilize ferromagnetic coupling between Fe2+ and Fe3+ cations. ?? 1986.
A comprehensive diagram to grow InAlN alloys by plasma-assisted molecular beam epitaxy
Fernandez-Garrido, S.; Gacevic, Z.; Calleja, E.
2008-11-10
Indium incorporation and surface morphology of InAlN layers grown on (0001) GaN by plasma-assisted molecular beam epitaxy were investigated as a function of the impinging In flux and the substrate temperature in the 450-610 deg. C range. In incorporation was found to decrease with substrate temperature due to thermal decomposition of the growing layer, while for a given temperature it increased with the impinging In flux until stoichiometry was reached at the growth front. The InN losses during growth followed an Arrhenius behavior characterized by an activation energy of 2.0 eV. A growth diagram highly instrumental to identify optimum growth conditions was established.
MOLE: a Voronoi diagram-based explorer of molecular channels, pores, and tunnels.
Petrek, Martin; Kosinová, Pavlína; Koca, Jaroslav; Otyepka, Michal
2007-11-01
We have developed an algorithm, "MOLE," for the rapid, fully automated location and characterization of molecular channels, tunnels, and pores. This algorithm has been made freely available on the Internet (http://mole.chemi.muni.cz/) and overcomes many of the shortcomings and limitations of the recently developed CAVER software. The core of our MOLE algorithm is a Dijkstra's path search algorithm, which is applied to a Voronoi mesh. Tests on a wide variety of biomolecular systems including gramicidine, acetylcholinesterase, cytochromes P450, potassium channels, DNA quadruplexes, ribozymes, and the large ribosomal subunit have demonstrated that the MOLE algorithm performs well. MOLE is thus a powerful tool for exploring large molecular channels, complex networks of channels, and molecular dynamics trajectories in which analysis of a large number of snapshots is required. PMID:17997961
Eutectics and Phase Diagrams of Molten Salts from Molecular Dynamics simulations
NASA Astrophysics Data System (ADS)
Jayaraman, Saivenkataraman; von Lilienfeld, Anatole; Thompson, Aidan
2011-03-01
The use of alkali nitrate salt mixtures as heat transfer fluids in solar thermal power plants is limited by their relatively high melting point. Certain compositions of quaternary and higher dimensional mixtures of alkali and alkaline earth nitrates and nitrites have low melting points. However, the high dimensionality of the search space makes it difficult to find lowest melting compositions. Molecular simulations offer an efficient way to screen for promising mixtures. A molecular dynamics scheme general enough to identify eutectics of any HTF candidate mixture will be presented. The eutectic mixture and temperature are located as the tangent point between free energies of mixing for the liquid and a linear plane connecting the pure solid-liquid free energy differences. The free energy of mixing of the liquid phase is obtained using thermodynamic integration over ``alchemical'' transmutations sampled with molecular dynamics, in which particle identities are swapped gradually. Numerical results for binary and ternary mixtures of alkali nitrates agree well with experimental measurements.
Schlegel, H. Bernhard
Molecular Orbital Study of the First Excited State of the OLED Material Tris(8-hydroxyquinoline)aluminum, Michigan 48202 Received February 6, 2001. Revised Manuscript Received May 16, 2001 Tris(8-hydroxyquinoline)aluminum
Metallic and molecular orbital concepts in XMg8 clusters, X = Be-F
NASA Astrophysics Data System (ADS)
Medel, Victor M.; Reber, Arthur C.; Ulises Reveles, J.; Khanna, Shiv N.
2012-04-01
The electronic structure and stability of the XMg8 clusters (X = Be, B, C, N, O, and F) are studied using first principles theoretical calculations to understand the variation in bonding in heteroatomic clusters which mix simple divalent metals with main group dopants. We examine these progressions with two competing models, the first is a distorted nearly free electron gas model and the second is a molecular orbital picture examining the orbital overlap between the dopant and the cluster. OMg8 is found to be the most energetically stable cluster due to strong bonding of O with the Mg8 cluster. BeMg8 has the largest HOMO-LUMO gap due to strong hybridization between the Mg8 and the Be dopant states that form a delocalized pool of 18 valence electrons with a closed electronic shell due to crystal field effects. Be, B, and C are best described by the nearly free electron gas model, while N, O, and F are best described through molecular orbital concepts.
Metallic and molecular orbital concepts in XMg8 clusters, X = Be-F.
Medel, Victor M; Reber, Arthur C; Reveles, J Ulises; Khanna, Shiv N
2012-04-01
The electronic structure and stability of the XMg(8) clusters (X = Be, B, C, N, O, and F) are studied using first principles theoretical calculations to understand the variation in bonding in heteroatomic clusters which mix simple divalent metals with main group dopants. We examine these progressions with two competing models, the first is a distorted nearly free electron gas model and the second is a molecular orbital picture examining the orbital overlap between the dopant and the cluster. OMg(8) is found to be the most energetically stable cluster due to strong bonding of O with the Mg(8) cluster. BeMg(8) has the largest HOMO-LUMO gap due to strong hybridization between the Mg(8) and the Be dopant states that form a delocalized pool of 18 valence electrons with a closed electronic shell due to crystal field effects. Be, B, and C are best described by the nearly free electron gas model, while N, O, and F are best described through molecular orbital concepts. PMID:22482556
Transport properties of lithium hydride at extreme conditions from orbital-free molecular dynamics
NASA Astrophysics Data System (ADS)
Burakovsky, L.; Ticknor, C.; Kress, J. D.; Collins, L. A.; Lambert, F.
2013-02-01
We have performed a systematic study of lithium hydride (LiH), using orbital-free molecular dynamics, with a focus on mass transport properties such as diffusion and viscosity by extending our previous studies at the lower end of the warm, dense matter regime to cover a span of densities from ambient to 10-fold compressed and temperatures from 10 eV to 10 keV. We determine analytic formulas for self- and mutual-diffusion coefficients, and viscosity, which are in excellent agreement with our molecular dynamics results, and interpolate smoothly between liquid and dense plasma regimes. In addition, we find the orbital-free calculations begin to agree with the Brinzinskii-Landau formula above about 250 eV at which point the medium becomes fully ionized. A binary-ion model based on a bare Coulomb interaction within a neutralizing background with the effective charges determined from a regularization prescription shows good agreement above about 100 eV with the orbital-free results. Finally, we demonstrate the validity of a pressure-based mixing rule in determining the transport properties from the pure-species quantities.
Orbit crowding of molecular gas at a bar-spiral arm transition zone in M83
NASA Technical Reports Server (NTRS)
Kenney, Jeffrey D. P.; Lord, Steven D.
1991-01-01
The southwestern bar-spiral arm transition zone in M83 is been studied in CO, H-alpha, H I, red light, and the radio continuum. A massive molecular gas complex in the heart of the transition zone is composed or two principal components which have the morphology and kinematics expected from orbit crowding, where gas on highly elliptical orbits form the bar region converges with gas on more circular orbits from the spiral arm region. Three mechanisms for the origin of the orbit crowding are investigated, and it is proposed that the crowding is due primarily to density wave streaming motions caused by the bar and spiral arms. The inner CO component is partially coincident with a region of highly polarized radio continuum emission which precedes the H-alpha spiral arm by 15-25 arcsec, indicating that it lies on or just downstream from a shock front. This suggests that the bar gas approaching the transition zone is shocked and explains the ridge of dense gas seen upstream from the spiral arm.
Barr, Al
: Validation for the phase diagram of Lennard-Jones fluids Shiang-Tai Lin, Mario Blanco, and William A. Goddard the gas, liquid, crystal, metastable, and unstable states in the phase diagram. Our results compare quite well with accurate Monte Carlo calculations of the phase diagram for classical Lennard-Jones particles
Fluorination-dependent molecular orbital occupancy in ring-shaped perfluorocarbons.
Brandenburg, Tim; Petit, Tristan; Neubauer, Antje; Atak, Kaan; Nagasaka, Masanari; Golnak, Ronny; Kosugi, Nobuhiro; Aziz, Emad F
2015-07-28
Perfluorocarbons are a family of molecules consisting mainly of carbon and fluorine atoms. They have interesting chemical properties and have diverse applications in biomedicine, physical chemistry and polymer science. In this work, carbon K-edge absorption and emission spectra of liquid decalin are presented and compared to perfluorodecalin. A comprehensive picture of the electronic structure of decalin is provided based on soft X-ray absorption and emission spectroscopies. Experimental data are compared to theoretical time-dependent density functional theory for the hydrocarbon, the perfluorocarbon and the stepwise fluorinated derivatives. We observed a molecular orbital change from unoccupied to occupied orbitals for perfluorodecalin, which was induced through the fluorination process. PMID:26105104
Study of the high-pressure helium phase diagram using molecular dynamics
NASA Astrophysics Data System (ADS)
Koci, L.; Ahuja, R.; Belonoshko, A. B.; Johansson, B.
2007-01-01
The rich occurrence of helium and hydrogen in space makes their properties highly interesting. By means of molecular dynamics (MD), we have examined two interatomic potentials for 4He. Both potentials are demonstrated to reproduce high-pressure solid and liquid equation of state (EOS) data. The EOS, solid-solid transitions and melting at high pressures (P) were studied using a two-phase method. The Buckingham potential shows a good agreement with theoretical and experimental EOS, but does not reproduce experimental melting data. The Aziz potential shows a perfect match with theoretical melting data. We conclude that there is a stable body-centred-cubic (bcc) phase for 4He at temperatures (T) above 340 K and pressures above 22 GPa for the Buckingham potential, whereas no bcc phase is found for the Aziz potential in the applied PT range.
Ab initio molecular orbital theory: a tool for THz spectroscopic investigation
NASA Astrophysics Data System (ADS)
Jones, Inke; Rainsford, Tamath J.; Mickan, Samuel P.; Abbott, Derek
2006-01-01
Terahertz spectroscopy, which investigates the electromagnetic spectrum of samples between 0.1 and 10 THz, allows not only for exploration of molecular structures but also of molecular dynamics. One difficulty in performing THz spectroscopy is that the data can be noisy and difficult to interpret. Ab initio molecular modelling has recently become more and more useful in the prediction of, for example, molecular structures, dynamic states and isomeric forms. Since the structure of biomolecules is closely related to their functionality there are broad ranging applications in biomedicine, for example in DNA sensing. An a priori knowledge of the expected THz spectra allows for improved experimentation. There is a growing and recognised need for THz spectroscopic databases to be created and made available along with classifiers that are able to effectively detect a specific substance. We show, for a specific example, the 9-cis and all-trans retinal isomers, how ab initio molecular orbital calculations and quantum chemical modelling programs, such as Gamess, can aid in this endeavour.
ERIC Educational Resources Information Center
Ruddick, Kristie R.; Parrill, Abby L.; Petersen, Richard L.
2012-01-01
In this study, a computational molecular orbital theory experiment was implemented in a first-semester honors general chemistry course. Students used the GAMESS (General Atomic and Molecular Electronic Structure System) quantum mechanical software (as implemented in ChemBio3D) to optimize the geometry for various small molecules. Extended Huckel…
Li, Shaowei; Yuan, Dingwang; Yu, Arthur; Czap, Gregory; Wu, Ruqian; Ho, W
2015-05-22
A hydrogen molecule can diffuse freely on the surface and be trapped above an adsorbed molecule within the junction of a scanning tunneling microscope. The trapped dihydrogen exhibits the properties of a free rotor. Here we show that the intermolecular interaction between dihydrogen and Mg-porphyrin (MgP) can be visualized by imaging j=0 to 2 rotational excitation of dihydrogen. The interaction leads to a weakened H-H bond and modest electron donation from the dihydrogen to the lowest unoccupied molecular orbital of MgP, a process similarly observed for the interaction between dihydrogen and an adsorbed Au atom. PMID:26047242
NASA Astrophysics Data System (ADS)
Li, Shaowei; Yuan, Dingwang; Yu, Arthur; Czap, Gregory; Wu, Ruqian; Ho, W.
2015-05-01
A hydrogen molecule can diffuse freely on the surface and be trapped above an adsorbed molecule within the junction of a scanning tunneling microscope. The trapped dihydrogen exhibits the properties of a free rotor. Here we show that the intermolecular interaction between dihydrogen and Mg-porphyrin (MgP) can be visualized by imaging j =0 to 2 rotational excitation of dihydrogen. The interaction leads to a weakened H-H bond and modest electron donation from the dihydrogen to the lowest unoccupied molecular orbital of MgP, a process similarly observed for the interaction between dihydrogen and an adsorbed Au atom.
Development of minimized mixing molecular orbital method for designing organic ferromagnets.
Zhu, Xun; Aoki, Yuriko
2015-06-15
Predicting the high spin stability of organic radicals correctly for designing organic ferromagnets remains a significant challenge. We have developed a method with an index (L(min)) for predicting the high spin stability of conjugated organic radicals at the restricted open-shell Hartree-Fock level. Unitary transformations were performed for localizing the coefficients of nonbonding molecular orbitals, and subsequently the localized coefficients were used to calculate L(min) that indicates the high spin stability of conjugated organic radicals. This method can be combined with the elongation method to treat huge high spin open-shell systems. Thus, this method is useful for designing organic ferromagnets. PMID:25903426
Imaging molecular orbitals by scanning tunneling microscopy on a passivated semiconductor.
Bellec, Amandine; Ample, Francisco; Riedel, Damien; Dujardin, Gérald; Joachim, Christian
2009-01-01
Decoupling the electronic properties of a molecule from a substrate is of crucial importance for the development of single-molecule electronics. This is achieved here by adsorbing pentacene molecules at low temperature on a hydrogenated Si(100) surface (12 K). The low temperature (5 K) scanning tunneling microscope (STM) topography of the single pentacene molecule at the energy of the highest occupied molecular orbital (HOMO) tunnel resonance clearly resembles the native HOMO of the free molecule. The negligible electronic coupling between the molecule and the substrate is confirmed by theoretical STM topography and diffusion barrier energy calculations. PMID:19090685
NASA Astrophysics Data System (ADS)
Watanabe, Hirofumi; Okiyama, Yoshio; Nakano, Tatsuya; Tanaka, Shigenori
2010-11-01
We developed FMO-PB method, which incorporates solvation effects into the Fragment Molecular Orbital calculation with the Poisson-Boltzmann equation. This method retains good accuracy in energy calculations with reduced computational time. We calculated the solvation free energies for polyalanines, Alpha-1 peptide, tryptophan cage, and complex of estrogen receptor and 17 ?-estradiol to show the applicability of this method for practical systems. From the calculated results, it has been confirmed that the FMO-PB method is useful for large biomolecules in solution. We also discussed the electric charges which are used in solving the Poisson-Boltzmann equation.
Counterpoise-corrected interaction energy analysis based on the fragment molecular orbital scheme
NASA Astrophysics Data System (ADS)
Okiyama, Yoshio; Fukuzawa, Kaori; Yamada, Haruka; Mochizuki, Yuji; Nakano, Tatsuya; Tanaka, Shigenori
2011-06-01
Basis set superposition error (BSSE) correction with counterpoise (CP) procedure under the environmental electrostatic potential is newly introduced to interfragment interaction energy (IFIE), which is important for interaction analysis in the fragment molecular orbital method. The CP correction for IFIE is applied to a stacked dimer of base pair and a protein-ligand complex of estrogen receptor and 17?-estradiol with scaled third-order Møller-Plesset perturbation theory. The BSSEs amount to about quarter of IFIE for hydrogen-bonding and electrostatic interactions and half or even more for dispersion interactions. Estimation of IFIE with the CP correction is therefore preferred for the quantitative discussion.
Improving the local vertex invariants in alkane graphs through a standard molecular orbital approach
NASA Astrophysics Data System (ADS)
Gálvez, J.; García-Domenech, R.
2007-11-01
In this work, novel topological indices are introduced by the application of algorithms based on molecular orbital theory. Actually, the novel indices are obtained by computing new values of the local vertex invariants (LOVIs) in alkane graphs. The most significant result is the dramatic increase in the predictive capability achieved with the topological charge indices weighted according the new LOVIs' values in the prediction of four key properties in the set of octane isomers, namely heat of atomization, molar refraction, heat of vaporization and boiling point.
Covalent features in the hydrogen bond of a water dimer: molecular orbital analysis
Wang, Bo; Dai, Xing; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin
2015-01-01
The covalent-like characteristics of hydrogen bonds offer a new perspective on intermolecular interactions. Here, using density functional theory and post-Hartree-Fock methods, we reveal that there are two bonding molecular orbitals (MOs) crossing the O and H atoms of the hydrogen-bond in water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. These results illustrate the covalent-like character of the hydrogen bond between water molecules, which contributes to the essential understanding of ice, liquid water, related materials, and life sciences.
Norris, Scott A; Samela, Juha; Bukonte, Laura; Backman, Marie; Djurabekova, Flyura; Nordlund, Kai; Madi, Charbel S; Brenner, Michael P; Aziz, Michael J
2011-01-01
Energetic particle irradiation can cause surface ultra-smoothening, self-organized nanoscale pattern formation or degradation of the structural integrity of nuclear reactor components. A fundamental understanding of the mechanisms governing the selection among these outcomes has been elusive. Here we predict the mechanism governing the transition from pattern formation to flatness using only parameter-free molecular dynamics simulations of single-ion impacts as input into a multiscale analysis, obtaining good agreement with experiment. Our results overturn the paradigm attributing these phenomena to the removal of target atoms via sputter erosion: the mechanism dominating both stability and instability is the impact-induced redistribution of target atoms that are not sputtered away, with erosive effects being essentially irrelevant. We discuss the potential implications for the formation of a mysterious nanoscale topography, leading to surface degradation, of tungsten plasma-facing fusion reactor walls. Consideration of impact-induced redistribution processes may lead to a new design criterion for stability under irradiation. PMID:21505432
Spin-orbit force, recoil corrections, and possible BB¯* and DD¯* molecular states
NASA Astrophysics Data System (ADS)
Zhao, Lu; Ma, Li; Zhu, Shi-Lin
2014-05-01
In the framework of the one-boson exchange model, we have calculated the effective potentials between two heavy mesons BB¯* and DD¯* from the t- and u-channel ?-, ?-, ?-, ?-, and ?-meson exchanges with four kinds of quantum number: I=0, JPC=1++; I =0, JPC=1+-; I =1, JPC=1++; I =1, JPC=1+-. We keep the recoil corrections to the BB¯* and DD¯* systems up to O(1/M2). The spin-orbit force appears at O(/1M), which turns out to be important for the very loosely bound molecular states. Our numerical results show that the momentum-related corrections are unfavorable to the formation of the molecular states in the I =0, JPC=1++ and I =1, JPC=1+- channels in the DD¯* system.
Modeling of hydroxyapatite-peptide interaction based on fragment molecular orbital method
NASA Astrophysics Data System (ADS)
Kato, Koichiro; Fukuzawa, Kaori; Mochizuki, Yuji
2015-06-01
We have applied the four-body corrected fragment molecular orbital (FMO4) calculations to analyze the interaction between a designed peptide motif (Glu1-Ser2-Gln3-Glu4-Ser5) and the hydroxyapatite (HA) solid mimicked by a cluster model consisting of 1408 atoms. To incorporate statistical fluctuations, a total of 30 configurations were generated through classical molecular dynamics simulation with water molecules and were subjected to FMO4 calculations at the MP2 level. It was found that Ser5 plays a leading role in interacting with the phosphate moieties of HA via charge transfer and also that negatively charged Glu1 and Glu4 provide electrostatic stabilizations with the calcium ions.
Electron-correlated fragment-molecular-orbital calculations for biomolecular and nano systems.
Tanaka, Shigenori; Mochizuki, Yuji; Komeiji, Yuto; Okiyama, Yoshio; Fukuzawa, Kaori
2014-06-14
Recent developments in the fragment molecular orbital (FMO) method for theoretical formulation, implementation, and application to nano and biomolecular systems are reviewed. The FMO method has enabled ab initio quantum-mechanical calculations for large molecular systems such as protein-ligand complexes at a reasonable computational cost in a parallelized way. There have been a wealth of application outcomes from the FMO method in the fields of biochemistry, medicinal chemistry and nanotechnology, in which the electron correlation effects play vital roles. With the aid of the advances in high-performance computing, the FMO method promises larger, faster, and more accurate simulations of biomolecular and related systems, including the descriptions of dynamical behaviors in solvent environments. The current status and future prospects of the FMO scheme are addressed in these contexts. PMID:24740821
Liquid Be, Ca and Ba. An orbital-free ab-initio molecular dynamics study
NASA Astrophysics Data System (ADS)
del Rio, B. G.; González, L. E.
2015-08-01
Several static and dynamic properties of liquid beryllium (l-Be), liquid calcium (l-Ca) and liquid barium (l-Ba) near their triple point have been evaluated by the orbital-free ab initio molecular dynamics method (OF-AIMD), where the interaction between valence electrons and ions is described by means of local pseudopotentials. These local pseudopotentials used were constructed through a force-matching process with those obtained from a Kohn-Sham ab initio molecular dynamics study (KS-AIMD) of a reduced system with non-local pseudopotentials. The calculated static structures show good agreement with the available experimental data, including an asymmetric second peak in the structure factor which has been linked to the existence of a marked icosahedral short-range order in the liquid. As for the dynamic properties, we obtain collective density excitations whose associated dispersion relations exhibit a positive dispersion.
A regression based model was developed to determine whether highest occupied molecular orbital (HOMO) energies, calculated using Kohn-Sham orbital density functional theory (DFT) could be used to estimate the OH rate constants of hydrofluorocarbons (HFCS) and hydrofluoroethers (H...
Resonating valence bond wave function with molecular orbitals: Application to first-row molecules
NASA Astrophysics Data System (ADS)
Marchi, Mariapia; Azadi, Sam; Casula, Michele; Sorella, Sandro
2009-10-01
We introduce a method for accurate quantum chemical calculations based on a simple variational wave function, defined by a single geminal that couples all the electrons into singlet pairs, combined with a real space correlation factor. The method uses a constrained variational optimization, based on an expansion of the geminal in terms of molecular orbitals. It is shown that the most relevant nondynamical correlations are correctly reproduced once an appropriate number n of molecular orbitals is considered. The value of n is determined by requiring that, in the atomization limit, the atoms are described by Hartree-Fock Slater determinants with Jastrow correlations. The energetics, as well as other physical and chemical properties, are then given by an efficient variational approach based on standard quantum Monte Carlo techniques. We test this method on a set of homonuclear (Be2, B2, C2, N2, O2, and F2) and heteronuclear (LiF and CN) dimers for which strong nondynamical correlations and/or weak van der Waals interactions are present.
Why many semiempirical molecular orbital theories fail for liquid water and how to fix them.
Welborn, Matthew; Chen, Jiahao; Wang, Lee-Ping; Van Voorhis, Troy
2015-05-01
Water is an extremely important liquid for chemistry and the search for more accurate force fields for liquid water continues unabated. Neglect of diatomic differential overlap (NDDO) molecular orbital methods provide and intriguing generalization of classical force fields in this regard because they can account both for bond breaking and electronic polarization of molecules. However, we show that most standard NDDO methods fail for water because they give an incorrect description of hydrogen bonding, water's key structural feature. Using force matching, we design a reparameterized NDDO model and find that it qualitatively reproduces the experimental radial distribution function of water, as well as various monomer, dimer, and bulk properties that PM6 does not. This suggests that the apparent limitations of NDDO models are primarily due to poor parameterization and not to the NDDO approximations themselves. Finally, we identify the physical parameters that most influence the condensed phase properties. These results help to elucidate the chemistry that a semiempirical molecular orbital picture of water must capture. We conclude that properly parameterized NDDO models could be useful for simulations that require electronically detailed explicit solvent, including the calculation of redox potentials and simulation of charge transfer and photochemistry. PMID:25766721
Danel, J.-F.; Kazandjian, L.; Zerah, G. [CEA, DAM, DIF, F-91297 Arpajon (France)
2012-12-15
The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on the Thomas-Fermi semiclassical approximation and possibly on a gradient correction, is the only simulation method currently available at high temperature. We show in the case of a dense boron plasma that the two approaches give pressures differing by a few percent even at temperatures as high as a few tens of electron-volts. We indicate how the pressures obtained by orbital-free molecular dynamics can be corrected in order to appear as a limit of the quantum molecular dynamics results as temperature increases. We thus obtain a method to calculate the equation of state of a dense plasma up to high temperatures where quantum molecular dynamics cannot be directly implemented.
Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M. [CEA, DAM, DIF, 91297 Arpajon (France)
2014-10-15
The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.
Generation of molecular symmetry orbitals for the point and double groups
NASA Astrophysics Data System (ADS)
Rykhlinskaya, K.; Fritzsche, S.
2005-09-01
Symmetry-adapted molecular basis functions are widely applied for the electronic structure computations of molecules and clusters. These functions are obtained by exploiting the symmetry of the system and often help to simplify the computations considerably. In order to facilitate their use in algebraic and numerical computations, here we provide a set of MAPLE procedures which generates these functions by means of projection operators, both within the nonrelativistic and relativistic theory. All commonly applied point and double groups are supported by the program including, in addition, the access to their group-theoretical data such as the symmetry operators, characters, or irreducible representations. Program summaryTitle of program:BETHE Catalogue identifier:ADVU Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVU Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:none Computer for which the program is designed: All computers with a license of the computer algebra package MAPLE (Maple is a registered trademark of Waterloo Maple Inc.) Installations:University of Kassel (Germany) Operating systems or monitors under which the program has been tested:Linux 8.1+ and Windows2000 Programming language used:MAPLE 7 and 8 Memory required to execute with typical data:10-30 MB No. of lines in distributed program, including test data, etc.:14 190 No. of bytes in distributed program, including test data, etc.:370 795 Distribution format:tar.gz Nature of the physical problem:Molecular and solid-state quantum computations can be simplified considerably if the symmetry of the systems with respect to the rotation and inversion of the coordinates is taken into account. To exploit such symmetries, however, symmetry-adapted basis functions need to be constructed instead of using—as usual—the atomic orbitals as the (one-particle) basis. These so-called symmetry orbitals are invariant with respect to the symmetry operations of the group and are different for the point and double groups, i.e. for nonrelativistic and relativistic computations. Method of solution:Projection operator techniques are applied to generate the symmetry-adapted orbital functions as a linear combinations of atomic orbitals. Restrictions onto the complexity of the problem:The generation of the symmetry orbitals is supported for the cyclic and related groups C, C, C, C, C, the dihedral groups D, D, D, the improper cyclic groups S2n(n?10), the cubic groups O, T, O, T, T as well as the icosahedral groups I and I. In all these cases, the symmetry orbitals can be obtained for either the point or double groups by using a nonrelativistic or, respectively, relativistic framework for the computations. Unusual features of the program:All commands of the BETHE program are available for interactive work. Apart from the symmetry orbitals generation, the program also provides a simple access to the group theoretical data for the presently implemented groups from above. The notation of the symmetry operations and the irreducible representations follows the compilation by Altmann and Herzig [Point-Group Theory Tables, Clarendon Press, Oxford, 1994]. For a quick reference to the program, a description of all user-relevant commands is given in the (user) manual Bethe-commands.ps and is distributed together with the code. Typical running time:Although the program replies 'promptly' on most requests, the running time depends strongly on the particular task.
Saju, K K; Jayadas, N H; Vidyanand, S; James, J
2011-03-01
It has been established that the adhesion of cells on to the surfaces of orthopaedic implants depends on the ability of the surfaces to accommodate protein molecules. Hydroxyapatite coating and anodizing are the most common methods to make TiAl6V4 implants (Ti) more biocompatible. In this paper Spartan 02, a molecular dynamics software, is used to analyze and predict the bonding characteristics of Extra cellular matrix protein sequence arginine-glycine-aspartic acid (RGD) on a Hyrdoxyapatite (HA) coated Ti and an anodized Ti surface based on the property of its constituent atoms, their polarity (net electrostatic charge, Qr), the energies of the molecular orbital E_HOMO (energy of the highest occupied molecular orbital), and E_LUMO (energy of the lowest unoccupied molecular orbital). The results show favourable criterion for formation of bonding between the HOMO orbital of the HA coated and anodized surfaces and LUMO orbital of the glycine strand from the RGD unit. The mechanism of bonding of individual atoms to form primary calcium oxide compounds is likely only in the case of HA coated surfaces . The surface texture of the anodized Ti with inherent porosities appear more responsible for the adsorption of proteins on to them by mechanical interlocking than the formation of any intermediate calcium oxide compounds. PMID:21485326
IMAGING THE MOLECULAR DISK ORBITING THE TWIN YOUNG SUNS OF V4046 Sgr
Rodriguez, David R. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Kastner, Joel H. [Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Wilner, David; Qi, Chunhua, E-mail: drodrigu@astro.ucla.ed, E-mail: jhk@cis.rit.ed, E-mail: dwilner@cfa.harvard.ed, E-mail: cqi@cfa.harvard.ed [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Mail Stop 42, Cambridge, MA 02138 (United States)
2010-09-10
We have imaged the disk surrounding the nearby (D {approx} 73 pc), {approx}12 Myr, classical T Tauri binary system V4046 Sgr with the Submillimeter Array (SMA) at an angular resolution of {approx}2''. We detect a rotating disk in {sup 12}CO(2-1) and {sup 13}CO(2-1) emission and resolve the continuum emission at 1.3 mm. We infer disk gas and dust masses of {approx}110 and {approx}40 Earth masses, respectively. Fits to a power-law disk model indicate that the molecular disk extends to {approx}370 AU and is viewed at an inclination of between {approx}33{sup 0} and {approx}39{sup 0} for dynamical stellar masses ranging from 1.8 M {sub sun} down to 1.5 M {sub sun} (the range of the total mass previously determined for the central, 2.4 day spectroscopic binary). This range of disk inclination is consistent with that assumed in deducing the central binary mass (i.e., 35{sup 0}), suggesting that the V4046 Sgr binary system and its circumbinary, molecular disk are coplanar. In light of the system's age and binarity, the presence of an extensive molecular disk orbiting V4046 Sgr provides constraints on the timescales of processes related to Jovian planet formation and demonstrates that circumbinary Jovian planets potentially could form around close binary systems.
Analytic second derivatives of the energy in the fragment molecular orbital method
NASA Astrophysics Data System (ADS)
Nakata, Hiroya; Nagata, Takeshi; Fedorov, Dmitri G.; Yokojima, Satoshi; Kitaura, Kazuo; Nakamura, Shinichiro
2013-04-01
We developed the analytic second derivatives of the energy for the fragment molecular orbital (FMO) method. First we derived the analytic expressions and then introduced some approximations related to the first and second order coupled perturbed Hartree-Fock equations. We developed a parallel program for the FMO Hessian with approximations in GAMESS and used it to calculate infrared (IR) spectra and Gibbs free energies and to locate the transition states in SN2 reactions. The accuracy of the Hessian is demonstrated in comparison to ab initio results for polypeptides and a water cluster. By using the two residues per fragment division, we achieved the accuracy of 3 cm-1 in the reduced mean square deviation of vibrational frequencies from ab initio for all three polyalanine isomers, while the zero point energy had the error not exceeding 0.3 kcal/mol. The role of the secondary structure on IR spectra, zero point energies, and Gibbs free energies is discussed.
Molecular orbital calculation of graphite K- V X-ray emission spectra
NASA Astrophysics Data System (ADS)
Kaneyoshi, Takahiro; Kowada, Yoshiyuki; Tanaka, Takeo; Kawai, Jun; Motoyama, Muneyuki
1999-01-01
The DV-X? molecular orbital (MO) calculation method has been applied to the carbon K- V X-ray emission spectra of graphite. The calculated 2 p density of states (DOS) of a larger model cluster, which avoided the influence of dangling bonds of the cluster edge, was in excellent agreement with the X-ray emission spectra. The calculated ? and ? subbands of 2 p DOS explained the polarized behavior of the spectra. The orientation of graphite was quantitatively discussed by means of polarization of the spectra. These results were applied to the analysis of the structural change of mechanical milled graphite; the structure change of the ball-milled graphite was studied by the X-ray spectroscopy and MO calculation. It was shown that the refinement of graphite powder occurred for up to 1000 h of milling, keeping the graphite structure, and that a further milling changed the C-C bonding within the graphite layer network.
NASA Astrophysics Data System (ADS)
Collado, J. R. Alvarez
A previous self-consistent field molecular orbital method, able to describe systems having a large number of unpaired electrons, n, is reviewed and improved. This method is applied to the study of paramagnetism in large (1,000-16,000 atoms) zigzag carbon nanotubes, represented by their n values. The computational scheme is based on the Hückel neglect differential overlap approach. It is shown that dependence of n on the semiempirical parameters is very small, and so they can be removed from the calculation. Enhancement of the paramagnetism (increase of n), by use of a strong external magnetic field, is also studied. Finally, the dependence of the Fermi one-electron potential energies and the spin atomic densities on both the parameters and the shape of the nanotubes is analyzed.0
Development of the four-body corrected fragment molecular orbital (FMO4) method
NASA Astrophysics Data System (ADS)
Nakano, Tatsuya; Mochizuki, Yuji; Yamashita, Katsumi; Watanabe, Chiduru; Fukuzawa, Kaori; Segawa, Katsunori; Okiyama, Yoshio; Tsukamoto, Takayuki; Tanaka, Shigenori
2012-01-01
The four-body corrected fragment molecular orbital (FMO4) method was implemented at the second-order Møller-Plesset perturbation (MP2) level. A series of accuracy tests relative to the previous two-body and three-body treatments were performed. As expected, FMO4 provided better accuracy in total energies in comparison with the reference values by regular MO calculations. A nonconventional fragmentation by separating main and side chains in amino acid residues was examined for Ala-pentamer and Chignolin, where the four-body corrections were shown to be substantial. A large complex of HIV-1 protease (total 198 residues) with lopinavir was calculated as well. Furthermore, this new FMO scheme was successfully applied to adamantane-shaped clusters with three-dimensional bonding framework.
Terao, Jun; Wadahama, Akihisa; Matono, Akitoshi; Tada, Tomofumi; Watanabe, Satoshi; Seki, Shu; Fujihara, Tetsuaki; Tsuji, Yasushi
2013-01-01
The feasibility of using ?-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of ?-conjugated polymers by covering the ?-conjugated chain with macrocycles and regularly localizing ?-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, insulated wires containing meta-junctioned poly(phenylene–ethynylene) as the backbone units were designed and synthesized. The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires. When the length of the linear region of the zigzag wires was increased to 10 phenylene–ethynylene units, the intramolecular charge mobility increased to 8.5?cm2?V?1?s?1. Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in ?-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes. PMID:23575695
Imaging superatomic molecular orbitals in a ${\\bf C_{60}}$ molecule through four 800-nm photons
Zhang, G P; Bai, Y H; Bonacum, J; Wu, X S; George, Thomas F
2015-01-01
Superatomic molecular orbitals (SAMO) in C60 are ideal building blocks for functional nanostructures. However, imaging them spatially in the gas phase has been unsuccessful. It is found experimentally that if C60 is excited by an 800-nm laser, the photoelectron casts an anisotropic velocity image, but the image becomes isotropic if excited at a 400-nm wavelength. This diffuse image difference has been attributed to electron thermal ionization, but more recent experiments (800 nm) reveal a clear non-diffuse image superimposed on the diffuse image, whose origin remains a mystery. Here we show that the non-diffuse anisotropic image is the precursor of the $f$ SAMO. We predict that four 800-nm photons can directly access the $1f$ SAMO, and with one more photon, can image the orbital, with the photoelectron angular distribution having two maxima at 0$^\\circ$ and 180$^\\circ$ and two humps separated by 56.5$^\\circ$. Since two 400-nm photons only resonantly excite the spherical $1s$ SAMO and four 800-nm photon excite...
Imaging superatomic molecular orbitals in a C60 molecule through four 800-nm photons
NASA Astrophysics Data System (ADS)
Zhang, G. P.; Zhu, H. P.; Bai, Y. H.; Bonacum, J.; Wu, X. S.; George, Thomas F.
2015-05-01
Superatomic molecular orbitals (SAMOs) in C60 are ideal building blocks for functional nanostructures. However, imaging them spatially in the gas phase has been unsuccessful. It is found experimentally that if C60 is excited by an 800-nm laser, the photoelectron casts an anisotropic velocity image, but the image becomes isotropic if excited at a 400-nm wavelength. This diffuse image difference has been attributed to electron thermal ionization, but more recent experiments (800 nm) reveal a clear nondiffuse image superimposed on the diffuse image, whose origin remains a mystery. Here we show that the nondiffuse anisotropic image is the precursor of the f SAMOs. We predict that four 800-nm photons can directly access the 1f SAMO, and with one more photon, can image the orbital, with the photoelectron angular distribution having two maxima at 0° and 180° and two humps separated by 56.5°. Since two 400-nm photons only resonantly excite the spherical 1s SAMO and four 800-nm photons excite the anisotropic 1f SAMO, our finding gives a natural explanation of the nondiffuse image difference, complementing the thermal scenario.
NASA Astrophysics Data System (ADS)
Yang, Weitao; Cohen, Aron J.; Mori-Sánchez, Paula
2012-05-01
The conventional analysis of Perdew and Levy, and Sham and Schlüter shows that the functional derivative discontinuity of the exchange-correlation density functional plays a critical role in the correct prediction of bandgaps, or the chemical hardness. In a recent work by the present authors, explicit expressions for bandgap prediction with all common types of exchange-correlation functionals have been derived without invoking the concept of exchange-correlation energy functional derivative discontinuity at all. We here analyze the two approaches and establish their connection and difference. The present analysis further leads to several important results: (1) The lowest unoccupied molecular orbital (LUMO) in DFT has as much meaning in describing electron addition as the highest occupied molecular orbital (HOMO) in describing electron removal. (2) Every term in the total energy functional contributes to the energy gap because of the discontinuity of the derivative of the density (or density matrix) with respect to the number of electrons, ((partial ? s({r^' }},{r}))/partial N )_{vs}, at integers. (3) Consistent with the Perdew-Levy-Sham-Schlüter conclusion that the exact Kohn-Sham energy gap differs from the fundamental bandgap by a finite correction due to the functional derivative discontinuity of the exchange-correlation energy, we show that the exchange-correlation functional cannot be an explicit and differentiable functional of the electron density, either local or nonlocal. The last result is further strengthened when we consider Mott insulators. There, the exact exchange-correlation functional needs to have an explicitly discontinuous (nondifferentiable) dependence on the density or the density matrix. (4) We obtain exact conditions on the derivatives of total energy with respect to the spin-up and spin-down number of electrons.
Jerry Ray Dias
1996-01-01
The correlations of properties and relationships of McClelland right-hand mirror-plane fragments (subgraphs) are presented. A complementary relationship is defined which has a strong analogy to the pairing relationship. Righthand mirror-plane fragments are molecular orbital functional groups and molecular graphs having the same mirror-plane fragments (functional groups) have a greater degree of similarity. Collections of subspectral structures are tabulated.
NASA Astrophysics Data System (ADS)
Habeeb, Moustafa M.; Al-Attas, Amirah S.; Al-Raimi, Doaa S.
2015-05-01
Charge transfer (CT) interaction between 3,5-dimethylpyrazole (DMP) with the ?-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ) has been investigated spectrophotometrically in acetonitrile (AN). Simultaneous reddish brown color has been observed upon mixing donor with acceptor solutions attributing to CT complex formation. The electronic spectra of the formed complex exhibited multi-charge transfer bands at 429, 447, 506, 542 and 589 nm, respectively. Job's method of continuous variations and spectrophotometric titration methods confirmed the formation of the studied complex in 1:2 ratio between DMP and DDQ. Benesi-Hildebrand equation has been applied to calculate the stability constant of the formed complex where it recorded high value supporting formation of stable complex. Molecular orbital calculations using MM2 method and GAMESS (General Atomic and Molecular Electronic Structure System) interface computations as a package of ChemBio3D Ultra12 software were carried out for more analysis of the formed complex in the gas phase. The computational analysis included energy minimisation, stabilisation energy, molecular geometry, Mullikan charges, molecular electrostatic potential (MEP) surfaces of reactants and complex as well as characterization of the higher occupied molecular orbitals (HOMO) and lower unoccupied molecular orbitals (LUMO) surfaces of the complex. A good consistency between experimental and theoretical results has been recorded.
Li, Xiao-Hong; Mei, Zheng; Zhang, Xian-Zhou
2014-01-24
The vibrational frequencies of acetophenone thiosemicarbazone in the ground state have been calculated using density functional method (B3LYP) with 6-31G(d), 6-31G(d,p) and 6-311++G(d,p) basis sets. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exist N-H…N and N-H…S hydrogen bonds in the title compound, which play a major role in stabilizing the molecule and are confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as second-order NLO material. In addition, the frontier molecular orbitals were analyzed and the crystal structure obtained by molecular mechanics belongs to the Pbca space group, with lattice parameters Z=8, a=16.0735 Å, b=7.1719 Å, c=7.8725 Å, ?=0.808 g/cm(3). PMID:24084483
NASA Astrophysics Data System (ADS)
Li, Xiao-Hong; Mei, Zheng; Zhang, Xian-Zhou
2014-01-01
The vibrational frequencies of acetophenone thiosemicarbazone in the ground state have been calculated using density functional method (B3LYP) with 6-31G(d), 6-31G(d,p) and 6-311++G(d,p) basis sets. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exist Nsbnd H…N and Nsbnd H…S hydrogen bonds in the title compound, which play a major role in stabilizing the molecule and are confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as second-order NLO material. In addition, the frontier molecular orbitals were analyzed and the crystal structure obtained by molecular mechanics belongs to the Pbca space group, with lattice parameters Z = 8, a = 16.0735 Å, b = 7.1719 Å, c = 7.8725 Å, ? = 0.808 g/cm3.
Liu, Shubin; Pedersen, Lee G.
2009-01-01
An effective approach of estimating molecular pKa values from simple density functional calculations is proposed in this work. Both the molecular electrostatic potential (MEP) at the nucleus of the acidic atom and the sum of valence natural atomic orbitals are employed for three categories of compounds, amines and anilines, carbonyl acids and alcohols, and sulfonic acids and thiols. A strong correlation between experimental pKa values and each of these two quantities for each of the three categories has been discovered. Moreover, if the MEP is subtracted by the isolated atomic MEP for each category of compounds, we observe a single unique linear relationship between the resultant MEP difference and experimental pKa data of amines, anilines, carbonyl acids, alcohols, sulfonic acids, thiols, and their substituents. These results can generally be utilized to simultaneously estimate pKa values at multiple sites with a single calculation for either relatively small molecules in drug design or amino acids in proteins and macromolecules. PMID:19317439
Kitoh-Nishioka, Hirotaka; Ando, Koji
2012-11-01
The tunneling mechanisms of electron transfers (ETs) in photosynthetic reaction center of Blastochloris viridis are studied by the ab initio fragment molecular orbital (FMO) method combined with the generalized Mulliken-Hush (GMH) and the bridge Green function (GF) calculations of the electronic coupling T(DA) and the tunneling current method for the ET pathway analysis at the fragment-based resolution. For the ET from batctriopheophytin (H(L)) to menaquinone (MQ), a major tunneling current through Trp M250 and a minor back flow via Ala M215, Ala M216, and His M217 are quantified. For the ET from MQ to ubiquinone, the major tunneling pathway via the nonheme Fe(2+) and His L190 is identified as well as minor pathway via His M217 and small back flows involving His L230, Glu M232, and His M264. At the given molecular structure from X-ray experiment, the spin state of the Fe(2+) ion, its replacement by Zn(2+), or its removal are found to affect the T(DA) value by factors within 2.2. The calculated T(DA) values, together with experimentally estimated values of the driving force and the reorganization energy, give the ET rates in reasonable agreement with experiments. PMID:23039745
NASA Technical Reports Server (NTRS)
Almloef, Jan; Taylor, Peter R.
1989-01-01
A recently proposed scheme for using natural orbitals from atomic configuration interaction (CI) wave functions as a basis set for linear combination of atomic orbitals (LCAO) calculations is extended for the calculation of molecular properties. For one-electron properties like multipole moments, which are determined largely by the outermost regions of the molecular wave function, it is necessary to increase the flexibility of the basis in these regions. This is most easily done by uncontracting the outmost Gaussian primitives, and/or by adding diffuse primitives. A similar approach can be employed for the calculation of polarizabilities. Properties which are not dominated by the long-range part of the wave function, such as spectroscopic constants or electric field gradients at the nucleus, can generally be treated satisfactorily with the original atomic natural orbital (ANO) sets.
Nguyen, Minh Tho
Mechanism of [2 + 1] Cycloadditions of Hydrogen Isocyanide to Alkynes: Molecular Orbital on the unsubstituted alkyne carbon is preferred. The hardness and polarizability profiles along the IRC reaction paths, there is a minimum in the hardness profile and a maximum in the polarizability profile, but these extrema do
Ewen, Pascal R; Sanning, Jan; Koch, Tobias; Doltsinis, Nikos L
2014-01-01
Summary The improvement of molecular electronic devices such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS) are powerful tools to correlate the electronic properties of phosphorescent complexes (i.e., triplet emitters) with their molecular structure as well as the local environment around a single molecule. We used spectroscopic mapping to visualize several occupied and unoccupied molecular frontier orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well-defined positions can alter specific molecular orbitals without influencing the others. The results open a path toward the tailored design of electronic and optical properties of triplet emitters by smart ligand substitution, which may improve the performance of future OLED devices. PMID:25551053
Ewen, Pascal R; Sanning, Jan; Koch, Tobias; Doltsinis, Nikos L; Strassert, Cristian A; Wegner, Daniel
2014-01-01
The improvement of molecular electronic devices such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS) are powerful tools to correlate the electronic properties of phosphorescent complexes (i.e., triplet emitters) with their molecular structure as well as the local environment around a single molecule. We used spectroscopic mapping to visualize several occupied and unoccupied molecular frontier orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well-defined positions can alter specific molecular orbitals without influencing the others. The results open a path toward the tailored design of electronic and optical properties of triplet emitters by smart ligand substitution, which may improve the performance of future OLED devices. PMID:25551053
Schlegel, H. Bernhard
Synthesis, Structure, Bridge-Terminal Exchange Kinetics, and Molecular Orbital Calculations of Pyrazolate-Bridged Digallium Complexes Containing Bridging Phenyl Groups Chatu T. Sirimanne, John E. KnoxVersity, Detroit, Michigan 48202 Received May 21, 2003; E-mail: chw@chem.wayne.edu Bridging of monoanionic
ERIC Educational Resources Information Center
Litofsky, Joshua; Viswanathan, Rama
2015-01-01
Matrix diagonalization, the key technique at the heart of modern computational chemistry for the numerical solution of the Schrödinger equation, can be easily introduced in the physical chemistry curriculum in a pedagogical context using simple Hückel molecular orbital theory for p bonding in molecules. We present details and results of…
George W. Luther III
2004-01-01
The kinetics of the reactions of water, hydroxide ion and sulfide species with CO2, OCS and CS2 are investigated using the molecular orbital approach and available kinetic data. Although these reactions are symmetry allowed, the lowest unoccupied molecular orbital (LUMO) for CO2 is a poor electron accepting orbital as it has a positive potential energy. At low pH, hydration of
NASA Astrophysics Data System (ADS)
Okamoto, Akisumi; Yano, Atsushi; Nomura, Kazuya; Higai, Shin'ichi; Kurita, Noriyuki
2013-07-01
Aggregation of amyloid ?-proteins (A?) plays a key role in the mechanism of molecular pathogenesis of Alzheimer’s disease (AD). It is known that full-length A?(1-42) is more prone to aggregation than A?(1-40). We here search stable conformations of solvated A?(1-42) monomer by replica exchange molecular dynamics simulations based on classical force fields, and the most stable conformation is determined from the total energies evaluated by the ab initio fragment molecular orbital (FMO) calculations. In addition, based on the FMO results, the amino acid residues of A?(1-42) contributing to the stabilization of the monomer are highlighted.
Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene
NASA Astrophysics Data System (ADS)
Serrano-Andrés, Luis; Merchán, Manuela; Nebot-Gil, Ignacio; Lindh, Roland; Roos, Björn O.
1993-02-01
A newly proposed quantum chemical approach for ab initio calculations of electronic spectra of molecular systems is applied to the molecules ethene, trans-1,3-butadiene, and trans-trans-1,3,5-hexatriene. The method has the aim of being accurate to better than 0.5 eV for excitation energies and is expected to provide structural and physical data for the excited states with good reliability. The approach is based on the complete active space (CAS) SCF method, which gives a proper description of the major features in the electronic structure of the excited state, independent of its complexity, accounts for all near degeneracy effects, and includes full orbital relaxation. Remaining dynamic electron correlation effects are in a subsequent step added using second order perturbation theory with the CASSCF wave function as the reference state. The approach is here tested in a calculation of the valence and Rydberg excited singlet and triplet states of the title molecules, using extended atomic natural orbital (ANO) basis sets. The ethene calculations comprised the two valence states plus all singlet and triplet Rydberg states of 3s, 3p, and 3d character, with errors in computed excitation energies smaller than 0.13 eV in all cases except the V state, for which the vertical excitation energy was about 0.4 eV too large. The two lowest triplet states and nine singlet states were studied in butadiene. The largest error (0.37 eV) was found for the 2 1Bu state. The two lowest triplet and seven lowest singlet states in hexatriene had excitation energies in error with less than 0.17 eV.
Thomas, T D; Kukk, E; Ouchi, T; Yamada, A; Fukuzawa, H; Ueda, K; Püttner, R; Higuchi, I; Tamenori, Y; Asahina, T; Kuze, N; Kato, H; Hoshino, M; Tanaka, H; Lindblad, A; Sæthre, L J
2010-11-01
Recoil-induced rotational excitation accompanying photoionization has been measured for the X, A, and B states of N(2)(+) and CO(+) over a range of photon energies from 60 to 900 eV. The mean recoil excitation increases linearly with the kinetic energy of the photoelectron, with slopes ranging from 0.73×10(-5) to 1.40×10(-5). These slopes are generally (but not completely) in accord with a simple model that treats the electrons as if they were emitted from isolated atoms. This treatment takes into account the atom from which the electron is emitted, the molecular-frame angular distribution of the electron, and the dependence of the photoelectron cross section on photon energy, on atomic identity, and on the type of atomic orbital from which the electron is ejected. These measurements thus provide a tool for investigating the atomic orbital composition of the molecular orbitals. Additional insight into this composition is obtained from the relative intensities of the various photolines in the spectrum and their variation with photon energy. Although there are some discrepancies between the predictions of the model and the observations, many of these can be understood qualitatively from a comparison of atomic and molecular wavefunctions. A quantum-mechanical treatment of recoil-induced excitation predicts an oscillatory variation with photon energy of the excitation. However, the predicted oscillations are small compared with the uncertainties in the data, and, as a result, the currently available results cannot provide confirmation of the quantum-mechanical theory. PMID:21054037
Lombardi, James C
2015-01-01
The present investigation relates the orbital radii of regular satellites of Uranus, Jupiter, Neptune, and Saturn to photon energies in the spectra of atomic and molecular hydrogen. To explain these observations a model is developed involving stimulated radiative molecular association (SRMA) reactions among the photons and atoms in the protosatellite disks of the planets. In this model thermal energy is extracted from each disk due to a resonance at radii where there is a match between the temperature in the disk and a photon energy. Matter accumulates at these radii, and satellites and rings are ultimately formed. Orbital radii of satellites of Uranus, Jupiter, and Neptune are related to photon energies ($E_{PM}$ values) in the spectrum of molecular hydrogen. Orbital radii of satellites of Saturn are related to photon energies ($E_{PA}$ values) in the spectrum of atomic hydrogen. The first hint that such relationships exist is found in the linearity of the graphs of orbital radii of uranian satellites vs. or...
Resonating Valence Bond wave function with molecular orbitals: first application to dimers
NASA Astrophysics Data System (ADS)
Sorella, Sandro; Azadi, Sam; Marchi, Mariapia; Casula, Michele
2009-03-01
We introduce a method for accurate quantum chemical calculations based on a single determinant wave function, the Antisymmetrized Geminal Power (AGP), and a real space correlation factor (the so called Jastrow factor), that can be efficiently sampled by means of standard quantum Monte Carlo techniques. This allows to obtain a very accurate description of the chemical bond even in extremely difficult cases (such as Be2, N2 and C2) where strong dynamical correlations and/or weak vdW interactions are present. The method is based on a constrained variational optimization, obtained with an appropriate number n of molecular orbitals in the AGP wavefunction. It is shown that the most relevant dynamical correlations are correctly reproduced, once n is univocally determined by the requirement to have size consistent results upon atomization to correlated Hartree-Fock Slater determinants in presence of the Jastrow factor. We apply this method to the Iron dimer molecule and obtain an accurate description of the ground state energy and excitations of this molecule, which is compatible with the experimental findings.
Structure of alkali tellurite glasses from neutron diffraction and molecular orbital calculations
NASA Astrophysics Data System (ADS)
Niida, Haruki; Uchino, Takashi; Jin, Jisun; Kim, Sae-Hoon; Fukunaga, Toshiharu; Yoko, Toshinobu
2001-01-01
The structure of pure TeO2 and alkali tellurite glasses has been examined by neutron diffraction and ab initio molecular orbital methods. The experimental radial distribution functions along with the calculated results have demonstrated that the basic structural units in tellurite glasses change from highly strained TeO4 trigonal bipyramids to more regular TeO3 trigonal pyramids with increasing alkali content. It has also been shown that the TeO3 trigonal pyramids do not exist in the form of isolated units in the glass network but interact with each other to form intertrigonal Te⋯O linkages. The present results suggest that nonbridging oxygen (NBO) atoms in tellurite glasses do not exist in their "pure" form; that is, all the NBO atoms in TeO3 trigonal bipyramids will interact with the first- and/or second-neighbor Te atoms, resulting in the three-dimensional continuous random network even in tellurite glasses with over 30 mol % of alkali oxides.
Rioux, Frank
Semi-emprical Molecular Orbital Calculation on XeF2 The bonding in XeF2 can be interpreted in terms the three-center four-electron bond. In linear XeF2 the molecular orbital can be considered to be a linear combination of the flourine 2p orbitals and the central xenon 5p. CF1 F1 CXe Xe+ CF2 F2+= Minimization
Luo, Qinlong; Dagotto, Elbio R
2014-01-01
Usingthereal-spaceHartree-Fockapproximation,themagneticphasediagramofa ve-orbitalHubbardmodelfortheiron-basedsuperconductorsisstudiedvaryingtheelectronicdensitynintherangefrom vetosevenelectronspertransitionmetalatom.TheHubbardinteractionUisalsovaried,ata xedHundcouplingJ/U=0.25.Severalqualitativetrendsandavarietyofcompetingmagneticstatesareobserved.Atn=5,arobustG-typeantiferromagneticinsulatorisfound,inagreementwithexperimentalresultsforBaMn2As2.Asnincreasesawayfrom5,magneticstateswithanincreasingnumberofnearest-neighborsferromagneticlinksbecomeenergeticallystable.Thisincludesthewell-knownC-typeantiferromagneticstateatn=6,theE-phaseknowntoexistinFeTe,andalsoavarietyofnovelstatesnotfoundyetexperimentally,someoftheminvolvingblocksofferromagneticallyorientedspins.Regionsofphaseseparation,asinMnoxides,havealsobeendetected.Comparisontoprevioustheoreticalinvestigationsindicatethatthesequalitativetrendsmaybegenericcharacteristicsofphasediagramsofmulti-orbitalHubbardmodels.
Chen, Ji; Ren, Xinguo; Li, Xin-Zheng; Alfè, Dario; Wang, Enge
2014-07-14
The finite-temperature phase diagram of hydrogen in the region of phase IV and its neighborhood was studied using the ab initio molecular dynamics (MD) and the ab initio path-integral molecular dynamics (PIMD). The electronic structures were analyzed using the density-functional theory (DFT), the random-phase approximation, and the diffusion Monte Carlo (DMC) methods. Taking the state-of-the-art DMC results as benchmark, comparisons of the energy differences between structures generated from the MD and PIMD simulations, with molecular and dissociated hydrogens, respectively, in the weak molecular layers of phase IV, indicate that standard functionals in DFT tend to underestimate the dissociation barrier of the weak molecular layers in this mixed phase. Because of this underestimation, inclusion of the quantum nuclear effects (QNEs) in PIMD using electronic structures generated with these functionals leads to artificially dissociated hydrogen layers in phase IV and an error compensation between the neglect of QNEs and the deficiencies of these functionals in standard ab initio MD simulations exists. This analysis partly rationalizes why earlier ab initio MD simulations complement so well the experimental observations. The temperature and pressure dependencies for the stability of phase IV were also studied in the end and compared with earlier results.
NSDL National Science Digital Library
This problem set challenges students to interpret a simplified temperature-composition phase diagram for the system enstatite (Mg2Si2O6) - diopside (CaMgSi2O6), which are common constituents of peridotites, gabbros, and basalts. Students are provided with the phase diagram and asked to answer 13 questions about it.
NSDL National Science Digital Library
This interactive problem provides an opportunity for children to become familiar with Venn diagrams, while reinforcing knowledge of number properties. Students must place the numbers from 1 to 40 into a Venn diagram of two sets with an intersection. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support.
Findlater, Alexander D; Zahariev, Federico; Gordon, Mark S
2015-04-16
The local correlation "cluster-in-molecule" (CIM) method is combined with the fragment molecular orbital (FMO) method, providing a flexible, massively parallel, and near-linear scaling approach to the calculation of electron correlation energies for large molecular systems. Although the computational scaling of the CIM algorithm is already formally linear, previous knowledge of the Hartree-Fock (HF) reference wave function and subsequent localized orbitals is required; therefore, extending the CIM method to arbitrarily large systems requires the aid of low-scaling/linear-scaling approaches to HF and orbital localization. Through fragmentation, the combined FMO-CIM method linearizes the scaling, with respect to system size, of the HF reference and orbital localization calculations, achieving near-linear scaling at both the reference and electron correlation levels. For the 20-residue alanine ? helix, the preliminary implementation of the FMO-CIM method captures 99.6% of the MP2 correlation energy, requiring 21% of the MP2 wall time. The new method is also applied to solvated adamantine to illustrate the multilevel capability of the FMO-CIM method. PMID:25794346
John B. Nicholas; A. J. Hopfinger; Robert J. Harrison; Lennox E. Iton; Larry A. Curtiss; R. E. Winans
1992-01-01
The structures, force constants, and relative acidities of a series of molecules that mimic the geometries of terminal and bridging hydroxyl groups in various substituted zeolites and clays are calculated by ab initio molecular orbital methods. The molecules are structural analogs of disiloxane H[sub 3]T-O-TH[sub 3], and the protonated form H[sub 3]T, Si, Al, B, and P. Also included are
M. E. Zandler; E. C. Behrman; M. B. Arrasmith; J. R. Myers; T. V. Smith
1996-01-01
We have performed semiempirical molecular orbital calculations, using the Austin Model 1# (AM1) and Parametric Method 3# (PM3) Hamiltonians of the program mopac for the geometric, electronic, and vibrational structure of (ZnO)n (where n = 1–16), spheroids, and (MX)12 analogs, where M = Be, Mg, Zn, Cd, Hg, Pb, Sn, Ge, Si, C when X = O, S and where
NASA Astrophysics Data System (ADS)
Roemelt, Michael
2015-07-01
Spin Orbit Coupling (SOC) is introduced to molecular ab initio density matrix renormalization group (DMRG) calculations. In the presented scheme, one first approximates the electronic ground state and a number of excited states of the Born-Oppenheimer (BO) Hamiltonian with the aid of the DMRG algorithm. Owing to the spin-adaptation of the algorithm, the total spin S is a good quantum number for these states. After the non-relativistic DMRG calculation is finished, all magnetic sublevels of the calculated states are constructed explicitly, and the SOC operator is expanded in the resulting basis. To this end, spin orbit coupled energies and wavefunctions are obtained as eigenvalues and eigenfunctions of the full Hamiltonian matrix which is composed of the SOC operator matrix and the BO Hamiltonian matrix. This treatment corresponds to a quasi-degenerate perturbation theory approach and can be regarded as the molecular equivalent to atomic Russell-Saunders coupling. For the evaluation of SOC matrix elements, the full Breit-Pauli SOC Hamiltonian is approximated by the widely used spin-orbit mean field operator. This operator allows for an efficient use of the second quantized triplet replacement operators that are readily generated during the non-relativistic DMRG algorithm, together with the Wigner-Eckart theorem. With a set of spin-orbit coupled wavefunctions at hand, the molecular g-tensors are calculated following the scheme proposed by Gerloch and McMeeking. It interprets the effective molecular g-values as the slope of the energy difference between the lowest Kramers pair with respect to the strength of the applied magnetic field. Test calculations on a chemically relevant Mo complex demonstrate the capabilities of the presented method.
Roemelt, Michael
2015-07-28
Spin Orbit Coupling (SOC) is introduced to molecular ab initio density matrix renormalization group (DMRG) calculations. In the presented scheme, one first approximates the electronic ground state and a number of excited states of the Born-Oppenheimer (BO) Hamiltonian with the aid of the DMRG algorithm. Owing to the spin-adaptation of the algorithm, the total spin S is a good quantum number for these states. After the non-relativistic DMRG calculation is finished, all magnetic sublevels of the calculated states are constructed explicitly, and the SOC operator is expanded in the resulting basis. To this end, spin orbit coupled energies and wavefunctions are obtained as eigenvalues and eigenfunctions of the full Hamiltonian matrix which is composed of the SOC operator matrix and the BO Hamiltonian matrix. This treatment corresponds to a quasi-degenerate perturbation theory approach and can be regarded as the molecular equivalent to atomic Russell-Saunders coupling. For the evaluation of SOC matrix elements, the full Breit-Pauli SOC Hamiltonian is approximated by the widely used spin-orbit mean field operator. This operator allows for an efficient use of the second quantized triplet replacement operators that are readily generated during the non-relativistic DMRG algorithm, together with the Wigner-Eckart theorem. With a set of spin-orbit coupled wavefunctions at hand, the molecular g-tensors are calculated following the scheme proposed by Gerloch and McMeeking. It interprets the effective molecular g-values as the slope of the energy difference between the lowest Kramers pair with respect to the strength of the applied magnetic field. Test calculations on a chemically relevant Mo complex demonstrate the capabilities of the presented method. PMID:26233112
NASA Astrophysics Data System (ADS)
Ariga, D.; Tanaka, M.; Kashiwabara, T.; Takahashi, Y.
2012-12-01
Chromium(Cr), molybdenum(Mo), and tungsten(W) are congeners which have some stable isotopes. Isotope ratios of Cr and Mo are used as tools to estimate redox state in paleocean. In addition, adsorption on Fe (hydr) oxide surfaces sometimes causes isotope fractionation for the oxyanions in the ocean. For example, the adsorption mechanisms of molybdate and tungstate on ferrihydrite are different although these elements are congeners: molybdate forms outer—sphere complex, but tungstate forms inner—sphere complex. This difference of adsorption mechanisms is related to isotope fractionation. However, adsorption mechanism of chromate on ferrihydrite has been unknown. Then, we performed EXAFS analysis to reveal adsorption mechanisms of chromate on Fe (hydr) oxides and molecular orbital (MO) calculation to consider the reactivity of oxyanions (chromate, molybdate, tungstate) on ferrihydrite. From the EXAFS analysis, it is suggested that chromate mainly forms outer—sphere complex on ferrihydrite. In addition, adsorption amount of chromate decreased as the ionic strength increased, which can be regarded as another evidence of the formation of outer—sphere complex. The results of MO calculations show that chromate and tungstate also showed that outer—sphere and inner—sphere complexes are stable on Fe (hydr) oxide, respectively. This result supports our experimental results using EXAFS. Moreover, the stabilities of hydration complex in water decreased in the order of chromate > molybdate > tungstate. Based on these results, it is suggested that formation of outer—sphere complex is less stable for tungstate, which allows us to conclude that chromate and molybdate prefer to form outer—sphere complexes, whereas tungstate to inner—sphere complex.
Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet
2015-02-01
In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n=1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts ((1)H and (13)C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results. PMID:25448933
NASA Astrophysics Data System (ADS)
Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet
2015-02-01
In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.
Pinjari, Rahul V.; Delcey, Mickaël G.; Guo, Meiyuan; Lundberg, Marcus, E-mail: marcus.lundberg@kemi.uu.se [Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20 Uppsala (Sweden); Odelius, Michael [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden)
2014-09-28
The metal L-edge (2p ? 3d) X-ray absorption spectra are affected by a number of different interactions: electron-electron repulsion, spin-orbit coupling, and charge transfer between metal and ligands, which makes the simulation of spectra challenging. The core restricted active space (RAS) method is an accurate and flexible approach that can be used to calculate X-ray spectra of a wide range of medium-sized systems without any symmetry constraints. Here, the applicability of the method is tested in detail by simulating three ferric (3d{sup 5}) model systems with well-known electronic structure, viz., atomic Fe{sup 3+}, high-spin [FeCl{sub 6}]{sup 3?} with ligand donor bonding, and low-spin [Fe(CN){sub 6}]{sup 3?} that also has metal backbonding. For these systems, the performance of the core RAS method, which does not require any system-dependent parameters, is comparable to that of the commonly used semi-empirical charge-transfer multiplet model. It handles orbitally degenerate ground states, accurately describes metal-ligand interactions, and includes both single and multiple excitations. The results are sensitive to the choice of orbitals in the active space and this sensitivity can be used to assign spectral features. A method has also been developed to analyze the calculated X-ray spectra using a chemically intuitive molecular orbital picture.
Hay, P.J.; Wadt, W.R.
1985-01-01
Ab initio effective core potentials (ECP's) have been generated to replace the innermost core electron for third-row (K--Au), fourth-row (Rb--Ag), and fifth-row (Cs--Au) atoms. The outermost core orbitals: corresponding to the ns/sup 2/np/sup 6/ configuration for the three rows here: are not replaced by the ECP but are treated on an equal footing with the nd, (n+1)s and (n+1)p valence orbitals. These ECP's have been derived for use in molecular calculations where these outer core orbitals need to be treated explicitly rather than to be replaced by an ECP. The ECP's for the forth and fifth rows also incorporate the mass--velocity and Darwin relativistic effects into the potentials. Analytic fits to the potentials are presented for use in multicenter integral evaluation. Gaussian orbital valence basis sets are developed for the (3s, 3p, 3d, 4s, 4p), (4s, 4p, 4d, 5s, 5p), and (5s, 5p, 5d, 6s, 6p) ortibals of the three respective rows.
Exact formulas for multipole moments using Slater-type molecular orbitals
NASA Technical Reports Server (NTRS)
Jones, H. W.
1986-01-01
A triple infinite sum of formulas expressed as an expansion in Legendre polynomials is generated by use of computer algebra to represent the potential from the midpoint of two Slater-type orbitals; the charge density that determines the potential is given as the product of the two orbitals. An example using 1s orbitals shows that only a few terms are needed to obtain four-figure accuracy. Exact formulas are obtained for multipole moments by means of a careful study of expanded formulas, allowing an 'extrapolation to infinity'. This Loewdin alpha-function approach augmented by using a C matrix to characterize Slater-type orbitals can be readily generalized to all cases.
NASA Astrophysics Data System (ADS)
Horn, Paul R.; Sundstrom, Eric Jon; Baker, Thomas A.; Head-Gordon, Martin
2013-04-01
Radical-closed shell and radical-radical intermolecular interactions are less well-understood than those between closed shell species. With the objective of gaining additional insight, this work reports a generalization of the absolutely localized molecular orbital (ALMO) energy decomposition analysis (EDA) to open shell fragments, described by self-consistent field methods, such as standard density functional theory. The ALMO-EDA variationally partitions an intermolecular interaction energy into three separate contributions; frozen orbital interactions, polarization, and charge transfer. The first examples involve comparison of the interactions of alkanes and alkyl radicals (methyl radical, methane, tertiary butyl radical, and isobutane) with sodium, potassium, hydronium, and ammonium cations. A second series of examples involve benzene cation interacting with a series of nucleophiles in both on-top and side-on geometries. The ALMO-EDA yields a variety of interesting insights into the relative roles of its component contributions as the interacting partners and their geometries are changed.
NASA Technical Reports Server (NTRS)
Roberts, W. W., Jr.; Stewart, G. R.
1987-01-01
The different roles played by orbital dynamics and dissipative cloud-cloud collisions in the formation of giant molecular clouds (GMCs) in a global spiral structure are investigated. The interstellar medium (ISM) is simulated by a system of particles, representing clouds, which orbit in a spiral-perturbed, galactic gravitational field. The overall magnitude and width of the global cloud density distribution in spiral arms is very similar in the collisional and collisionless simulations. The results suggest that the assumed number density and size distribution of clouds and the details of individual cloud-cloud collisions have relatively little effect on these features. Dissipative cloud-cloud collisions play an important steadying role for the cloud system's global spiral structure. Dissipative cloud-cloud collisions also damp the relative velocity dispersion of clouds in massive associations and thereby aid in the effective assembling of GMC-like complexes.
Horn, Paul R; Sundstrom, Eric Jon; Baker, Thomas A; Head-Gordon, Martin
2013-04-01
Radical-closed shell and radical-radical intermolecular interactions are less well-understood than those between closed shell species. With the objective of gaining additional insight, this work reports a generalization of the absolutely localized molecular orbital (ALMO) energy decomposition analysis (EDA) to open shell fragments, described by self-consistent field methods, such as standard density functional theory. The ALMO-EDA variationally partitions an intermolecular interaction energy into three separate contributions; frozen orbital interactions, polarization, and charge transfer. The first examples involve comparison of the interactions of alkanes and alkyl radicals (methyl radical, methane, tertiary butyl radical, and isobutane) with sodium, potassium, hydronium, and ammonium cations. A second series of examples involve benzene cation interacting with a series of nucleophiles in both on-top and side-on geometries. The ALMO-EDA yields a variety of interesting insights into the relative roles of its component contributions as the interacting partners and their geometries are changed. PMID:23574220
NASA Astrophysics Data System (ADS)
Chen, Mohan; Xia, Junchao; Huang, Chen; Dieterich, Johannes M.; Hung, Linda; Shin, Ilgyou; Carter, Emily A.
2015-05-01
Orbital-free density functional theory (OFDFT) is a linear-scaling first-principles quantum mechanics method used to calculate the ground-state energy of a given system. Here we present a new version of PRinceton Orbital-Free Electronic Structure Software (PROFESS) with new features. First, PROFESS 3.0 provides a set of new kinetic energy density functionals (KEDFs) which are designed to model semiconductors or transition metals. Specifically, PROFESS 3.0 includes the Huang-Carter (HC) KEDF [1], a density decomposition method with fixed localized electronic density [2], the Wang-Govind-Carter (WGC) decomposition KEDF [3], and the Enhanced von Weizsäcker (EvW)-WGC KEDF [4]. Other major new functions are included, such as molecular dynamics with different statistical mechanical ensembles and spin-polarized density optimizers.
Yoshida, Tatsusada; Lepp, Zsolt; Kadota, Yoshito; Satoh, Yurie; Itoh, Kohji; Chuman, Hiroshi
2006-01-01
Cathepsin A is a mammalian lysosomal enzyme that catalyzes the hydrolysis of the carboxy-terminal amino acids of polypeptides and also regulates beta-galactosidase and neuraminidase-1 activities through the formation of a multienzymic complex in lysosomes. Human cathepsin A (hCathA), yeast carboxypeptidase (CPY), and wheat carboxypeptidase II (CPW) belong to the alpha/beta-hydrolase fold family. They have structurally similar active-site clefts, but there are small differences in the amino acid residues comprising their active sites that might determine the substrate specificity and sensitivity to microbial inhibitors including chymostatin. To examine the selectivity and binding mechanism of chymostatin as to hCathA, CPY, and CPW at the atomic level, we analyzed the interaction energy between chymostatin and each protein quantitatively by semiempirical molecular orbital calculation AM1 with the continuum solvent model. We predicted the electrostatic repulsion between the P3 cyclic arginine residue of the inhibitor and the Arg344 in the S3 active subsite of hCathA. Genetic conversion of Arg344 of the wild-type hCathA to Ile also caused an increase in its sensitivity to chymostatin, which was correlated with the decrease in the interaction energy calculated with the molecular orbital method. The present results suggest that such molecular calculation should be useful for evaluating the interactions between ligands, including inhibitors and homologous enzymes, in their docking models. PMID:16995740
Mehta, Somil C; Somasundaran, P; Kulkarni, Ravi
2009-05-15
Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not received much attention. Ionic silicones have significantly different properties than the non-ionic counterpart. Thus considerable potential exists to formulate emulsions of silicones with different water/silicone oil ratios for novel applications. In order to understand the mechanisms underlying the effects of hydrophilic modifications on the ability of hybrid silicone polymers to stabilize various emulsions, this article focuses on the phase diagram studies for silicone emulsions. The emulsifying ability of functional silicones was seen to depend on a number of factors including hydrophilicity of the polymer, nature of the functional groups, the extent of modification, and the method of emulsification. It was observed that the region of stable emulsion in a phase diagram expanded with increase in shear rate. At a given shear rate, the region of stable emulsion and the nature of emulsion (water-in-oil or oil-in-water) was observed to depend on hydrophilic-hydrophobic balance of the hybrid silicone emulsifier. At a fixed amount of modification, the non-ionically modified silicone stabilized an oil-in-water emulsion, whereas the ionic silicones stabilized inverse water-in-oil emulsions. This was attributed to the greater hydrophilicity of the polyoxyethylene modified silicones than the ionic counterparts. In general, it is postulated that with progressive increase in hydrophilicity of hybrid silicone emulsifiers, their tendency to stabilize water-in-oil emulsion decreases with corresponding increase in oil-in-water emulsion. Further, this behavior is hypothesized to depend on the nature of modifying functional groups. Thus a hybrid silicone polymer can be tailored by selecting the nature and degree of hydrophilicity to obtain a desired silicone emulsion. PMID:19200558
Bhuiyan, G M; González, D J; 10.5488/CMP.15.33604
2012-01-01
Several static and dynamic properties of liquid Cu, Ag and Au at thermodynamic states near their respective melting points, have been evaluated by means of the orbital free ab-initio molecular dynamics simulation method. The calculated static structure shows good agreement with the available X-ray and neutron diffraction data. As for the dynamic properties, the calculated dynamic structure factors point to the existence of collective density excitations along with a positive dispersion for l-Cu and l-Ag. Several transport coefficients have been obtained which show a reasonable agreement with the available experimental data.
G. M. Bhuiyan; L. E. González; D. J. González
2012-10-08
Several static and dynamic properties of liquid Cu, Ag and Au at thermodynamic states near their respective melting points, have been evaluated by means of the orbital free ab-initio molecular dynamics simulation method. The calculated static structure shows good agreement with the available X-ray and neutron diffraction data. As for the dynamic properties, the calculated dynamic structure factors point to the existence of collective density excitations along with a positive dispersion for l-Cu and l-Ag. Several transport coefficients have been obtained which show a reasonable agreement with the available experimental data.
NSDL National Science Digital Library
National Science Digital Library (NSDL) Middle School Portal Staff
2008-03-10
These online resources offer varied opportunities to work with Venn diagrams, one of many tools used in logic and reasoning. Their use is especially helpful in learning foundational notions of definition and set theory. One of the five Process Standards promoted by NCTM, Reasoning and Proof requires middle school students to sharpen such skills as they learn to develop mathematical argument.
Hirano, Toshiyuki; Sato, Fumitoshi
2014-07-28
We used grid-free modified Cholesky decomposition (CD) to develop a density-functional-theory (DFT)-based method for calculating the canonical molecular orbitals (CMOs) of large molecules. Our method can be used to calculate standard CMOs, analytically compute exchange-correlation terms, and maximise the capacity of next-generation supercomputers. Cholesky vectors were first analytically downscaled using low-rank pivoted CD and CD with adaptive metric (CDAM). The obtained Cholesky vectors were distributed and stored on each computer node in a parallel computer, and the Coulomb, Fock exchange, and pure exchange-correlation terms were calculated by multiplying the Cholesky vectors without evaluating molecular integrals in self-consistent field iterations. Our method enables DFT and massively distributed memory parallel computers to be used in order to very efficiently calculate the CMOs of large molecules. PMID:24622472
Hohenstein, Edward G; Bouduban, Marine E F; Song, Chenchen; Luehr, Nathan; Ufimtsev, Ivan S; Martínez, Todd J
2015-07-01
The floating occupation molecular orbital-complete active space configuration interaction (FOMO-CASCI) method is a promising alternative to the state-averaged complete active space self-consistent field (SA-CASSCF) method. We have formulated the analytic first derivative of FOMO-CASCI in a manner that is well-suited for a highly efficient implementation using graphical processing units (GPUs). Using this implementation, we demonstrate that FOMO-CASCI gradients are of similar computational expense to configuration interaction singles (CIS) or time-dependent density functional theory (TDDFT). In contrast to CIS and TDDFT, FOMO-CASCI can describe multireference character of the electronic wavefunction. We show that FOMO-CASCI compares very favorably to SA-CASSCF in its ability to describe molecular geometries and potential energy surfaces around minimum energy conical intersections. Finally, we apply FOMO-CASCI to the excited state hydrogen transfer reaction in methyl salicylate. PMID:26156469
NASA Astrophysics Data System (ADS)
Mok, Michelle; Burghardt, Wesley; Ellison, Christopher; Torkelson, John
2009-03-01
Traditionally, phase transitions of block copolymers could only be tuned through molecular weight and relative block length. Here, we introduce comonomer sequence design through gradient compositions as a means of further manipulating phase diagram boundaries. In such gradient copolymers, the reduced repulsion between chain segments allows access to phase transitions even at high molecular weights (MW). Rheological and x-ray scattering studies were performed to study the impact of comonomer sequence on phase behavior in styrene/n-butyl acrylate (S/nBA) systems. In S/nBA block copolymers, only upper critical ordering behavior was observed. In contrast, by using a gradient architecture of higher MW we observed both upper and lower ordering transitions similar to those seen in very weakly segregating S/n-butyl methacrylate block copolymers, where such dual ordering transitions were first detected by Russell et al. This is the first study to access a miscibility gap in gradient copolymers. Access to such behavior is very rare in blends and block copolymers, limited to low MW and/or very weakly segregating systems.
NASA Astrophysics Data System (ADS)
Balachandran, V.; Karunakaran, V.
2014-06-01
The FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-100 cm-1) of 2,3,4,5,6-pentafluorophenylacetic acid (PAA) have been recorded. Density functional theory calculation with LSDA/6-31+G(d,p) and B3LYP/6-31+G(d,p) basis sets have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman intensities and bonding features of the title compound. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of PAA are calculated using B3LYP/6-31+G(d,p) method on the finite-field approach. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The stability of molecule has been analyzed by using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within this molecule. Mulliken population analysis on atomic charges is also calculated. Thermodynamic properties (heat capacity, enthalpy, Gibb's free energy and entropy) of the title compound at different temperatures were calculated.
Molecular orbital (SCF-X?-SW) theory of metal-metal charge transfer processes in minerals
Sherman, David M.
1987-01-01
Electronic transitions between the Fe-Fe bonding and Fe-Fe antibonding orbitals results in the optically-induced intervalence charge transfer bands observed in the electronic spectra of mixed valence minerals. Such transitions are predicted to be polarized along the metal-metal bond direction, in agreement with experimental observations.
ERIC Educational Resources Information Center
Gillespie, Ronald J.; And Others
1996-01-01
Presents an alternative approach to bonding and geometry--the electron domain model--which avoids some of the problems with the conventional approach. Discusses difficulties with the orbital model at the introductory level, electron spin and the Pauli exclusion principle, electron pair domains, nonequivalent domains, multiple bonds, and origins…
Ito, Tomoyasu; Tashiro, Toshihiko; Kawasaki, Mineko; Watanabe, Tomoko; Toi, Keio (Tokyo Metropolitan Univ. (Japan)); Kobayashi, Hisayoshi (Kyoto Prefectural Univ. (Japan))
1991-05-30
Chemisorptions of CH{sub 4} on well-degassed MgO were examined by means of the temperature-programmed desorption and ab initio molecular orbital methods. Three types of chemisorptions (M{sub 1}, M{sub 2}, and IM) were found experimentally, all of which are very similar in nature and give heterolytically dissociated species, CH{sub 3}{sup {minus}} and H{sup +}. The active site M{sub 1} consists of the nearest pair of low-coordinated ions, Mg{sub LC}{sup 2+} and O{sub LC}{sup 2{minus}}, while the M{sub 2} and the IM sites consist of an isolated pair of them. Therefore, M{sub 1} adsorption could proceed even below room temperature but M{sub 2} IM adsorptions were observable only under severe adsorption conditions. The molecular orbital calculations strongly supported the above experimental results, especially the presence of the M{sub 1} adsorption. Among four models examined, only heterolytic adsorption which led to Mg-CH{sub 3} and O-H bond formations gave a stable product with an activation energy of 10.7 kcal mol{sup {minus}1} at the MP2 level (or 7.2 kcal mol{sup {minus}1} at the HF level).
NASA Astrophysics Data System (ADS)
Biswas, P. K.; Gogonea, Valentin
2008-10-01
We present an ab initio polarizable representation of classical molecular mechanics (MM) atoms by employing an angular momentum-based expansion scheme of the point charges into partial wave orbitals. The charge density represented by these orbitals can be fully polarized, and for hybrid quantum-mechanical-molecular-mechanical (QM/MM) calculations, mutual polarization within the QM/MM Hamiltonian can be obtained. We present the mathematical formulation and the analytical expressions for the energy and forces pertaining to the method. We further develop a variational scheme to appropriately determine the expansion coefficients and then validate the method by considering polarizations of ions by the QM system employing the hybrid GROMACS-CPMD QM/MM program. Finally, we present a simpler prescription for adding isotropic polarizability to MM atoms in a QM/MM simulation. Employing this simpler scheme, we present QM/MM energy minimization results for the classic case of a water dimer and a hydrogen sulfide dimer. Also, we present single-point QM/MM results with and without the polarization to study the change in the ionization potential of tetrahydrobiopterin (BH4) in water and the change in the interaction energy of solvated BH4 (described by MM) with the P450 heme described by QM. The model can be employed for the development of an extensive classical polarizable force-field.
Localized and Spectroscopic Orbitals: Squirrel Ears on Water.
ERIC Educational Resources Information Center
Martin, R. Bruce
1988-01-01
Reexamines the electronic structure of water considering divergent views. Discusses several aspects of molecular orbital theory using spectroscopic molecular orbitals and localized molecular orbitals. Gives examples for determining lowest energy spectroscopic orbitals. (ML)
Palii, Andrei; Tsukerblat, Boris; Klokishner, Sophia; Dunbar, Kim R; Clemente-Juan, Juan M; Coronado, Eugenio
2011-06-01
In this critical review we review the problem of exchange interactions in polynuclear metal complexes involving orbitally degenerate metal ions. The key feature of these systems is that, in general, they carry an unquenched orbital angular momentum that manifests itself in all their magnetic properties. Thus, interest in degenerate systems involves fundamental problems related to basic models in magnetism. In particular, the conventional Heisenberg-Dirac-Van Vleck model becomes inapplicable even as an approximation. In the first part we attempt to answer two key questions, namely which theoretical tools are to be used in the case of degeneracy, and how these tools can be employed. We demonstrate that the exchange interaction between orbitally degenerate metal ions can be described by the so-called orbitally-dependent exchange Hamiltonian. This approach has shown to reveal an anomalously strong magnetic anisotropy that can be considered as the main physical manifestation of the unquenched orbital angular momentum in magnetic systems. Along with the exchange coupling, a set of other interactions (such as crystal field effects, spin-orbit and Zeeman coupling), which are specific for the degenerate systems, need to be considered. All these features will be discussed in detail using a pseudo-spin-1/2 Hamiltonian approach. In the second part, the described theoretical background will be used to account for the magnetic properties of several magnetic metal clusters and low-dimensional systems: (i) the dinuclear face-sharing unit [Ti(2)Cl(9)](3-), which exhibits a large magnetic anisotropy; (ii) the rare-earth compounds Cs(3)Yb(2)Cl(9) and Cs(3)Yb(2)Br(9), which, surprisingly, exhibit a full magnetic isotropy; (iii) a zig-zag Co(II) chain exhibiting unusual combination of single-chain magnet behavior and antiferromagnetic exchange coupling; (iv) a trigonal bipyramidal Ni(3)Os(2) complex; (v) various Co(II) clusters encapsulated by polyoxometalate ligands. In the two last examples a pseudospin-1/2 Hamiltonian approach is applied to account for the presence of exchange anisotropy (150 references). PMID:21431145
Kortright, Jeffrey B; Kortright, Jeffrey B; Lincoln, Derek M; Edelstein, Ruth Shima; Epstein, Arthur J
2008-05-20
X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (MCD) at the V L2,3 and C and N K edges reveal bonding/backbonding interactions in films of the 400 K magnetic semiconductor V[TCNE]x~;;2. In V spectra, dxy-like orbitals are modeled assuming V2+ in an octahedral ligand field, while dz2 and dx2-y2 orbitals involved in strong covalent bonding cannot be modeled by atomic calculations. C and N MCD, and differences in XAS from neutral TCNE molecules, reveal spin-polarized molecular orbitals in V[TCNE]x~;;2 associated with backbonding interactions that yield its novel properties.
Neese, Frank
2005-01-15
Approximations to the Breit-Pauli form of the spin-orbit coupling (SOC) operator are examined. The focus is on approximations that lead to an effective quasi-one-electron operator which leads to efficient property evaluations. In particular, the accurate spin-orbit mean-field (SOMF) method developed by Hess, Marian, Wahlgren, and Gropen is examined in detail. It is compared in detail with the "effective potential" spin-orbit operator commonly used in density functional theory (DFT) and which has been criticized for not including the spin-other orbit (SOO) contribution. Both operators contain identical one-electron and Coulomb terms since the SOO contribution to the Coulomb term vanishes exactly in the SOMF treatment. Since the DFT correlation functional only contributes negligibly to the SOC the only difference between the two operators is in the exchange part. In the SOMF approximation, the SOO part is equal to two times the spin-same orbit contribution. The DFT exchange contribution is of the wrong sign and numerically shown to be in error by a factor of 2-2.5 in magnitude. The simplest possible improvement in the DFT-SOC treatment [Veff(-2X)-SOC] is to multiply the exchange contribution to the Veff operator by -2. This is verified numerically in calculations of molecular g-tensors and one-electron SOC constants of atoms and ions. Four different ways of handling the computationally critical Coulomb part of the SOMF and Veff operators are discussed and implemented. The resolution of the identity approximation is virtually exact for the SOC with standard auxiliary basis sets which need to be slightly augmented by steep s functions for heavier elements. An almost as efficient seminumerical approximation is equally accurate. The effective nuclear charge model gives results within approximately 10% (on average) of the SOMF treatment. The one-center approximation to the Coulomb and one-electron SOC terms leads to errors on the order of approximately 5%. Small absolute errors are obtained for the one-center approximation to the exchange term which is consequently the method of choice [SOMF(1X)] for large molecules. PMID:15740192
Okumura, Hironori, E-mail: okumura@engineering.ucsb.edu; McSkimming, Brian M.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States); Huault, Thomas; Chaix, Catherine [RIBER S.A., 3a Rue Casimir Perier, BP 70083, 95873 Bezons Cedex (France)] [RIBER S.A., 3a Rue Casimir Perier, BP 70083, 95873 Bezons Cedex (France)
2014-01-06
N-face GaN was grown on free-standing GaN (0001{sup ¯}) substrates at a growth rate of 1.5??m/h using plasma-assisted molecular beam epitaxy. Difference in growth rate between (0001{sup ¯}) and (0001) oriented GaN depends on nitrogen plasma power, and the (0001{sup ¯}) oriented GaN had only 70% of the growth rate of the (0001) oriented GaN at 300?W. Unintentional impurity concentrations of silicon, carbon, and oxygen were 2?×?10{sup 15}, 2?×?10{sup 16}, and 7?×?10{sup 16}?cm{sup ?3}, respectively. A growth diagram was constructed that shows the dependence of the growth modes on the difference in the Ga and active nitrogen flux, ?{sub Ga}????{sub N*}, and the growth temperature. At high ?{sub Ga}????{sub N*} (?{sub Ga}????{sub N*}), two-dimensional (step-flow and layer-by-layer) growth modes were realized. High growth temperature (780?°C) expanded the growth window of the two-dimensional growth modes, achieving a surface with rms roughness of 0.48?nm without Ga droplets.
Rodrigues, Alessandro; Olivato, Paulo R; Zukerman-Schpector, Julio; Maganhi, Stella H; Reis, Adriana K C A; Tiekink, Edward R T
2015-08-13
The X-ray single crystal analysis of isomeric ortho, meta, and para bromo-substituted ?-methylsulfonyl-?-diethoxyphosphoryl acetophenones showed that this class of compound adopts synclinal (gauche) conformations for both [-P(O)(OEt)2] and [-S(O)2Me] groups, with respect to the carbonyl functional group. The phosphonate, sulfonyl, and carbonyl functional groups are joined through an intramolecular network of attractive interactions, as detected by molecular orbital calculations at the M06-2X/6-31G(d,p) level. These interactions are responsible for the more stable conformations in the gas phase, which also persist in the solid-state structures. The main structural distinction in the title compounds relates to the torsion angle of the aryl group (with respect to the carbonyl group), which gives rise to different interactions in the crystal packing, due to the different positions of the Br atom. PMID:26213179
NASA Astrophysics Data System (ADS)
Ozaki, Hiroyuki; Harada, Yoshiya
1990-03-01
Penning ionization electron spectra (PIES) and ultraviolet photoelectron spectra (UPS) were measured for two kinds of ultrathin films of iron phthalocyanine with different orientation of surface molecules. The local electron distribution of molecular orbitals (MO) at the different parts of the molecule was reflected in the PIES. From this the character of MOs responsible for each band in the PIES and UPS was revealed. The so-called iron 3d bands were assigned to 3d? (dxz, dyz, dz2)-like MOs. The IP values for ? MOs were found to be less than ˜12 eV in the solid phase. It was concluded that the type of MOs probed by PIES can be selected if the orientation of molecules is controlled appropriately, which will be of great help to elucidate the electronic structure of complex molecules.
NASA Astrophysics Data System (ADS)
Korek, M.; Hammoud, S.; Allouche, A. R.; Harb, T.
2008-11-01
The potential energy has been calculated for the 42 lowest electronic states of symmetries ? =1/2,3/2,5/2, for the molecular ion RbH+. Using an ab initio method, the calculation is based on nonempirical pseudopotentials and parametrized ?-dependent polarization potentials. Gaussian basis sets have been used for both atoms, and spin-orbit effects have been taken into account. The spectroscopic constants for 19 electronic states have been calculated by fitting the calculated energy values to a polynomial in terms of the internuclear distance r. The permanent dipole moment and the transition dipole moments have been calculated for the considered ? states. Through the canonical functions approach the eigenvalue Ev, the abscissas of the corresponding turning points (rmin and rmax) and the rotational constants Bv have been calculated. The comparison of the present results with those available in literature shows a very good agreement.
Nano Res. 2011, 4(6): 523530 523 Direct Imaging of Molecular Orbitals of Metal Phthalocyanines
Gao, Hongjun
-molecular or even atomic scale. This could be accomplished by decoupling molecules from the substrate, for example phthalocyanine and zinc phthalocyanine molecules on Au(111) have been obtained using a functionalized tip tip with O2. The detailed structures are differentiated only when interacting with the highly
Thirman, Jonathan; Head-Gordon, Martin
2015-08-28
An energy decomposition analysis (EDA) of intermolecular interactions is proposed for second-order Møller-Plesset perturbation theory (MP2) based on absolutely localized molecular orbitals (ALMOs), as an extension to a previous ALMO-based EDA for self-consistent field methods. It decomposes the canonical MP2 binding energy by dividing the double excitations that contribute to the MP2 wave function into classes based on how the excitations involve different molecules. The MP2 contribution to the binding energy is decomposed into four components: frozen interaction, polarization, charge transfer, and dispersion. Charge transfer is defined by excitations that change the number of electrons on a molecule, dispersion by intermolecular excitations that do not transfer charge, and polarization and frozen interactions by intra-molecular excitations. The final two are separated by evaluations of the frozen, isolated wave functions in the presence of the other molecules, with adjustments for orbital response. Unlike previous EDAs for electron correlation methods, this one includes components for the electrostatics, which is vital as adjustment to the electrostatic behavior of the system is in some cases the dominant effect of the treatment of electron correlation. The proposed EDA is then applied to a variety of different systems to demonstrate that all proposed components behave correctly. This includes systems with one molecule and an external electric perturbation to test the separation between polarization and frozen interactions and various bimolecular systems in the equilibrium range and beyond to test the rest of the EDA. We find that it performs well on these tests. We then apply the EDA to a halogen bonded system to investigate the nature of the halogen bond. PMID:26328835
Yoshida, Norio
2014-06-07
The three-dimensional reference interaction site model (3D-RISM) method was efficiently implemented in the fragment molecular orbital (FMO) method. The method is referred to as the FMO/3D-RISM method, and allows us to treat electronic structure of the whole of a macromolecule, such as a protein, as well as the solvent distribution around a solute macromolecule. The formalism of the FMO/3D-RISM method, for the computationally available form and variational expressions, are proposed in detail. A major concern leading to the implementation of the method was decreasing the computational costs involved in calculating the electrostatic potential, because the electrostatic potential is calculated on numerous grid points in three-dimensional real space in the 3D-RISM method. In this article, we propose a procedure for decreasing the computational costs involved in calculating the electrostatic potential in the FMO method framework. The strategy involved in this procedure is to evaluate the electrostatic potential and the solvated Fock matrix in different manners, depending on the distance between the solute and the solvent. The electrostatic potential is evaluated directly in the vicinity of the solute molecule by integrating the molecular orbitals of monomer fragments of the solute molecule, whereas the electrostatic potential is described as the sum of multipole interactions when an analog of the fast multipole method is used. The efficiency of our method was demonstrated by applying it to a water trimer system and three biomolecular systems. The FMO/3D-RISM calculation can be performed within a reasonable computational time, retaining the accuracy of some physical properties.
NASA Astrophysics Data System (ADS)
Pati, Ranjit; Karna, Shashi P.
2002-01-01
The dependence of electron transfer (ET) coupling element, VAB, on the length of rigid-rod-like systems consisting of bicyclo[1.1.1]pentane (BCP), cubane (CUB), and bicyclo[2.2.2]octane (BCO) monomers, has been investigated with the use of ab initio Hartree-Fock (HF) method employing Marcus-Hush two-state (TS) model. The value of VAB decreases exponentially with increase in the number of the cage units of the ?-bonded molecules. The calculated decay constant, ?, shows good agreement with previously reported data. For molecular length?15 Å, the value of VAB becomes negligibly small, suggesting complete suppression of the through bond direct tunneling contribution to ET process.
An orbital-free self-consistent field approach for molecular clusters and liquids
Sean W. Derrickson; Eric R. Bittner
2005-10-31
We present an ``orbital'' free density functional theory for computing the quantum ground state of atomic clusters and liquids. Our approach combines the Bohm hydrodynamical description of quantum mechanics with an information theoretical approach to determine an optimal quantum density function in terms of density approximates to a statistical sample. The ideas of Bayesian statistical analysis and an expectation-maximization procedure are combined to develop approximations to the quantum density and thus find the approximate quantum force. The quantum force is then combined with a Lennard-Jones force to simulate clusters of Argon atoms and to obtain the ground state configurations and energies. As demonstration of the utility and flexibility of the approach, we compute the lowest energy structures for small rare-glass clusters. Extensions to many atom systems is straightforward.
Rings of C2H in the Molecular Disks Orbiting TW Hya and V4046 Sgr
Kastner, J H; Gorti, U; Hily-Blant, P; Oberg, K; Forveille, T; Andrews, S; Wilner, D
2015-01-01
We have used the Submillimeter Array to image, at ~1" resolution, C2H(3-2) emission from the molecule-rich circumstellar disks orbiting the nearby, classical T Tauri star systems TW Hya and V4046 Sgr. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology within each disk, the inner hole radius of the C2H ring within the V4046 Sgr disk (~70 AU) is somewhat larger than than of its counterpart within the TW Hya disk (~45 AU). We suggest that, in each case, the C2H emission likely traces irradiation of the tenuous surface layers of the outer disks by high-energy photons from the central stars.
NASA Astrophysics Data System (ADS)
Zarycz, M. Natalia C.; Sauer, Stephan P. A.; Provasi, Patricio F.
2014-10-01
We discuss the effect of electron correlation on the unexpected differential sensitivity (UDS) in the 1J(C-H) coupling constant of CH4 using a decomposition into contributions from localized molecular orbitals and compare with the 1J(N-H) coupling constant in NH3. In particular, we discuss the well known fact that uncorrelated coupled Hartree-Fock (CHF) calculations are not able to reproduce the UDS in methane. For this purpose we have implemented for the first time a localized molecular orbital analysis for the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes—SOPPA(CCSD) in the DALTON program. Comparing the changes in the localized orbital contributions at the correlated SOPPA and SOPPA(CCSD) levels and at the uncorrelated CHF level, we find that the latter overestimates the effect of stretching the bond between the coupled atoms on the contribution to the coupling from the localized bonding orbital between these atoms. This disturbs the subtle balance between the molecular orbital contributions, which lead to the UDS in methane.
Suresh, S; Gunasekaran, S; Srinivasan, S
2014-05-01
The solid phase FT-IR and FT-Raman spectra of 2-[2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetyl] oxyacetic acid (Aceclofenac) have been recorded in the region 4000-400 and 4000-100 cm(-1) respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies were scaled and have been compared with experimental by obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method employed to study its absorption energy and oscillator strength. The linear polarizability (?) and the first order hyper polarizability (?) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) were also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. PMID:24556133
NASA Astrophysics Data System (ADS)
Suresh, S.; Gunasekaran, S.; Srinivasan, S.
The solid phase FT-IR and FT-Raman spectra of 2-[2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetyl] oxyacetic acid (Aceclofenac) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies were scaled and have been compared with experimental by obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method employed to study its absorption energy and oscillator strength. The linear polarizability (?) and the first order hyper polarizability (?) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) were also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.
Chang, Le; Ishikawa, Takeshi; Kuwata, Kazuo; Takada, Shoji
2013-05-30
Accurate computational estimate of the protein-ligand binding affinity is of central importance in rational drug design. To improve accuracy of the molecular mechanics (MM) force field (FF) for protein-ligand simulations, we use a protein-specific FF derived by the fragment molecular orbital (FMO) method and by the restrained electrostatic potential (RESP) method. Applying this FMO-RESP method to two proteins, dodecin, and lysozyme, we found that protein-specific partial charges tend to differ more significantly from the standard AMBER charges for isolated charged atoms. We did not see the dependence of partial charges on the secondary structure. Computing the binding affinities of dodecin with five ligands by MM PBSA protocol with the FMO-RESP charge set as well as with the standard AMBER charges, we found that the former gives better correlation with experimental affinities than the latter. While, for lysozyme with five ligands, both charge sets gave similar and relatively accurate estimates of binding affinities. PMID:23420697
Zhan, Chang-Guo; Nichols, Jeffrey A.; Dixon, David A.
2003-05-22
Representative atomic and molecular systems, including various inorganic and organic molecules with covalent and ionic bonds, have been studied by using density functional theory. The calculations were done with the commonly used exchange-correlation functional B3LYP followed by a comprehensive analysis of the calculated highest-occupied and lowest-unoccupied Kohn-Sham orbital (HOMO and LUMO) energies. The basis set dependence of the DFT results shows that the economical 6-31+G* basis set is generally sufficient for calculating the HOMO and LUMO energies (if the calculated LUMO energies are negative) for use in correlating with molecular properties. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (c), hardness (h), and first electron excitation energy (t) are all in good agreement with the available experimental data. A generally applicable linear correlation relationship exists between the calculated HOMO energies and the experimental/calculated IP's. We have also found satisfactory linear correlation relationships between the calculated LUMO energies and experimental/calculated EA's (for the bound anionic states), between the calculated average HOMO/LUMO energies and c values, between the calculated HOMO-LUMO energy gaps and h values, and between the calculated HOMO-LUMO energy gaps and experimental/calculated first excitation energies. By using these linear correlation relationships, the calculated HOMO and LUMO energies can be employed to semi-quantitatively estimate ionization potential, electron affinity, electronegativity, hardness, and first excitation energy.
Newton, James Edward
1982-01-01
-workers. These authors also descr1bed the paramagnet1c triplet 16 state of the oxyhemoglobin molecule through the sp1n-pa1r1ng model. We report here the results of approximate self-cons1stent field molecular orbital (NO) and ab initio mult1configuration self...
Prabavathi, N; Senthil Nayaki, N; Venkatram Reddy, B
2015-02-01
Vibrational spectral analysis of the molecules 3,6-dichloro-4-methylpyridazine (DMP) and 3,6-dichloropyridazine-4-carboxylic acid (DPC) was carried out using FT-IR and FT-Raman spectroscopic techniques. The molecular structure and vibrational spectra of DMP and DPC were obtained by the density functional theory (DFT) method, using B3LYP functional, with 6-311++G(d,p) basis set. A detailed interpretation of the Infrared and Raman spectra of the two molecules were reported based on potential energy distribution (PED). The theoretically predicted FTIR and FT-Raman spectra of the titled molecules have been simulated and were compared with the experimental spectra. Determination of electric dipole moment (?) and hyperpolarizability ?0 helps to study the non-linear optical (NLO) behavior of DMP and DPC. Stability of the molecules arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. (13)C and (1)H NMR spectra were recorded and (13)C and (1)H NMR chemical shifts of the molecules were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compounds was also recorded in the region 200-1100 nm and electronic properties, HOMO (Highest Occupied Molecular Orbitals) and LUMO (Lowest Unoccupied Molecular Orbitals) energies were measured by time-dependent TD-DFT approach. Charge density distribution and site of chemical reactivity of the molecule have been studied by mapping electron density isosurface with molecular electrostatic potential (MESP). PMID:25459510
A Ring of C2H in the Molecular Disk Orbiting TW Hya
Kastner, Joel H; Gorti, Uma; Hily-Blant, Pierre; Oberg, Karin; Forveille, Thierry; Andrews, Sean; Wilner, David
2015-01-01
We have used the Submillimeter Array to image, at ~1.5" resolution, C2H (3-2) emission from the circumstellar disk orbiting the nearby (D = 54 pc), ~8 Myr-old, ~0.8 Msun classical T Tauri star TW Hya. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology. Based on a model in which the C2H column density follows a truncated radial power-law distribution, we find that the inner edge of the ring lies at ~45 AU, and that the ring extends to at least ~120 AU. Comparison with previous (single-dish) observations of C2H (4-3) emission indicates that the C2H molecules are subthermally excited and, hence, that the emission arises from the relatively warm, tenuous upper atmosphere of the disk. We propose that the C2H emission most likely traces particularly efficient photo-destruction of small grains and/or photodesorption and photodissociation of hydrocarbons derived from grain ice mantles in the surface layers of the outer disk. The presence of a C2H ring in the TW Hya disk hence likely serves ...
A Ring of C2H in the Molecular Disk Orbiting TW Hya
NASA Astrophysics Data System (ADS)
Kastner, Joel H.; Qi, Chunhua; Gorti, Uma; Hily-Blant, Pierre; Oberg, Karin; Forveille, Thierry; Andrews, Sean; Wilner, David
2015-06-01
We have used the Submillimeter Array to image, at ?1.?5 resolution, C2H N=3\\to 2 emission from the circumstellar disk orbiting the nearby (D = 54 pc), ?8 Myr-old, ?0.8 {{M}? } classical T Tauri star TW Hya. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology. Based on a model in which the C2H column density follows a truncated radial power-law distribution, we find that the inner edge of the ring lies at ?45 AU, and that the ring extends to at least ?120 AU. Comparison with previous (single-dish) observations of C2H N=4\\to 3 emission indicates that the C2H molecules are subthermally excited and, hence, that the emission arises from the relatively warm (T? 40 K), tenuous (n\\ll {{10}7} cm?3) upper atmosphere of the disk. Based on these results and comparisons of the SMA C2H map with previous submillimeter and scattered-light imaging, we propose that the C2H emission most likely traces particularly efficient photo-destruction of small grains and/or photodesorption and photodissociation of hydrocarbons derived from grain ice mantles in the surface layers of the outer disk. The presence of a C2H ring in the TW Hya disk hence likely serves as a marker of dust grain processing and radial and vertical grain size segregation within the disk.
Kowalczykowski, Stephen C.
2/27/14 10:11 AMTopology diagram and electronic density maps. : Structural and mechani...MI1 : Nature Structural & Molecular Biology : Nature Publishing Group Page 1 of 2http://www.nature.com/nsmb/journal/vaop/ncurrent/fig_tab/nsmb.2775_SF4.html Supplementary Figure 4: Topology diagram and electronic density maps. From Structural
NASA Astrophysics Data System (ADS)
Saunders, M. W.
1981-06-01
If during a visit to an inhabited but undeveloped planet orbiting a distant star, it were decided to make information available at a later, technically advanced, stage of its civilization, one way of doing this would be to use a radio transmission from earth. The transmission could be made so low in power that it would be likely to be received by the inhabitants only after details of its wavelength and direction had been supplied, for example, by a local transmitter installed on a nearby moon. This paper examines the possibility of making information available in this way and considers how the direction of the radio transmission from earth could be indicated by the use of a star distance diagram.
Lee, Minju; Zimmermann-Steffens, Saskia G; Arey, J Samuel; Fenner, Kathrin; von Gunten, Urs
2015-08-18
Second-order rate constants (kO3) for the reaction of ozone with micropollutants are essential parameters for the assessment of micropollutant elimination efficiency during ozonation in water and wastewater treatment. Prediction models for kO3 were developed for aromatic compounds, olefins, and amines by quantum chemical molecular orbital calculations employing ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods. The kO3 values for aromatic compounds correlated well with the energy of a delocalized molecular orbital first appearing on an aromatic ring (i.e., the highest occupied molecular orbital (HOMO) or HOMO-n (n ? 0) when the HOMO is not located on the aromatic ring); the number of compounds tested (N) was 112, and the correlation coefficient (R(2)) values were 0.82-1.00. The kO3 values for olefins and amines correlated well with the energy of a localized molecular orbital (i.e., the natural bond orbital (NBO)) energy of the carbon-carbon ? bond of olefins (N = 45, R(2) values of 0.82-0.85) and the NBO energy of the nitrogen lone-pair electrons of amines (N = 59, R(2) values of 0.81-0.83), respectively. Considering the performance of the kO3 prediction model and the computational costs, the HF/6-31G method is recommended for all aromatic groups and olefins investigated herein, whereas the HF/MIDI!, HF/6-31G*, or HF/6-311++G** methods are recommended for amines. Based on their mean absolute errors, the above models could predict kO3 within a factor of 4, on average, relative to the experimentally determined values. Overall, good correlations were also observed (R(2) values of 0.77-0.96) between kO3 predictions by quantum molecular orbital descriptors in this study and by the Hammett (?) and Taft (?*) constants from previously developed quantitative structure-activity relationship (QSAR) models. Hence, the quantum molecular orbital descriptors are an alternative to ? and ?*-values in QSAR applications and can also be utilized to estimate unknown ? or ?*-values. ?. PMID:26121114
Spectroscopic studies, potential energy surface and molecular orbital calculations of pramipexole
NASA Astrophysics Data System (ADS)
Muthu, S.; Uma Maheswari, J.; Srinivasan, S.; Isac paulraj, E.
2013-11-01
A systematic vibrational spectroscopic assignment and analysis of pramipexole [(S)-N6-propyl-4,5,6,7-tetrahydro-1,3-benzothiazole-2,6-diamine] has been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G(d, p) and cc-pVTZ basis sets. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption ?max were determined by time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PEDs) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. In addition, the potential energy surface, HOMO and LUMO energies, the molecular electrostatic potential and the first-order hyperpolarizability have been computed. The magnitude of the first-order hyperpolarizability is 5 times larger than that of urea and the title compound may be a potential applicant for the development of NLO materials.
Arcisauskaite, Vaida; Knecht, Stefan; Sauer, Stephan P A; Hemmingsen, Lars
2012-12-14
We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spin-orbit coupling) for predictions of electric field gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by comparing with benchmark DFT and CCSD-T data (Arcisauskaite et al., Phys. Chem. Chem. Phys., 2012, 14, 2651-2657) obtained from 4-component Dirac-Coulomb Hamiltonian calculations. The investigated set of molecules comprises linear HgL(2) (L = Cl, Br, I, CH(3)) and bent HgCl(2) mercury compounds as well as the trigonal planar [HgCl(3)](-) system. In 4-component calculations we used the dyall.cv3z basis set for Hg, Br, I and the cc-pCVTZ basis set for H, C, Cl, whereas in ZORA calculations we used the QZ4P basis set for all the atoms. ZORA-4 reproduces the fully relativistic 4-component DFT reference values within 6% for all studied Hg compounds and employed functionals (BH&H, BP86, PBE0), whereas scalar relativistic (SR)-ZORA-4 results show deviations of up to 15%. Compared to our 4-component CCSD-T benchmark the BH&H functional performs best at both 4-component and ZORA levels. We furthermore observe that changes in the largest component of the diagonalised EFG tensor, V(zz), of linear HgCl(2) show a slightly stronger dependence than the r(-3) scaling upon bond length r(Hg-Cl) alterations. The 4-component/BH&H V(zz) value of -9.26 a.u. for a bent HgCl(2) (?Cl-Hg-Cl = 120°) is close to -9.60 a.u. obtained for the linear HgCl(2) structure. Thus a point charge model for EFG calculations completely fails in this case. By means of a projection analysis of molecular orbital (MO) contributions to V(zz) in terms of the atomic constituents, we conclude that this is due to the increased importance of the Hg 5d orbitals upon bending HgCl(2) compared to the linear HgCl(2) structure. Changing ligand leads to only minor changes in V(zz) (from -9.60 a.u. (HgCl(2)) to -8.85 a.u. (HgI(2)) at the 4-component/BH&H level). This appears to be due to cancellation of contributions with opposite signs to V(zz) arising from: (i) increasing electron donation from occupied ligand orbitals to the formally empty Hg 6p orbitals and (ii) an increasing bond length and a decreasing negative charge on the ligand along the series. PMID:23111689
Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi
2015-07-01
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl(-) + CH3Cl ? ClCH3 + Cl(-)) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF. PMID:26156461
NASA Astrophysics Data System (ADS)
Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi
2015-07-01
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl- + CH3Cl ? ClCH3 + Cl-) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
Tromp, Moniek; van Bokhoven, Jeroen A; van Strijdonck, Gino P F; van Leeuwen, Piet W N M; Koningsberger, Diek C; Ramaker, David E
2005-01-19
Pd K-edge X-ray absorption near-edge spectroscopy (XANES) is used to probe the unoccupied molecular orbitals in bidentate diphosphine Pd complexes. Complexes containing a series of bidentate diphosphine ligands (PP) are examined to study the effect of the ligand bite angle on the charge redistribution in these complexes. Different coordinating moieties (XX) have been used to induce a range of Pd oxidation states. A full interpretation of the Pd K-edge XANES data is presented. The negative second derivative of these XANES data provides direct information on the energy and electronic distribution of the different unoccupied molecular orbitals probed. The charge redistributions within the complexes, as reflected in the effective Pd oxidation state, are indicated by both the intensity of the first edge feature, the "Pd d peak", and the energy of the second edge feature, the "Pd p peak", which can be easily observed in the negative second derivative of the XANES data. Additionally, the changing covalent interaction between the Pd and coordinated moieties via the Pd p orbitals is reflected directly in the energy splitting of the "Pd p" peak. Thus, investigation of these (PP)Pd(XX) complexes, some used as catalysts in organic synthesis, with XANES spectroscopy provides new essential information on their electronic properties. Further, the XANES analysis techniques described in this paper can be applied to investigate the unoccupied molecular orbitals and charge redistributions within a wide range of samples. PMID:15643904
NASA Technical Reports Server (NTRS)
Bagus, P. S.; Bauschlicher, C. W., Jr.; Nelin, C. J.; Laskowski, B. C.; Seel, M.
1984-01-01
The interaction of CO with Cu5, Ni5, and Al4 are treated as model systems for molecular adsorption on metal surfaces. The effect of the use of pseudopotentials for the metal atoms is studied by considering three types of clusters. In the first case, all of the metal electrons are explicitly included in the wave function; an all electron (AE) treatment. In the second case, the metal atom which directly interacts with the CO is described by AE but the remaining metal atoms include a pseudopotential for their core electrons. Finally, in the third case, all of the metal atoms in the cluster have a pseudopotential treatment for the core electrons. The AE cluster results are taken as reference values for the two pseudopotential treatments. The mixed cluster results are in excellent agreement with those of the all AE clusters; however, the results for the all pseudopotential cluster of Ni5CO or of Cu5CO are qualitatively different. The pseudopotential treatment for all of the metal atoms often leads to results that contain serious errors and it is not a reliable approach.
Tawa, G.J.; Pratt, L.R.; Martin, R.L.
1996-12-31
We present a method for computing the electrostatic component of the solvation free energy, {Delta}G{sup el}, of a solute molecule in the presence of solvent modeled as a dielectric continuum. The method is based on an integral form of Poisson`s equation which is solved to obtain a distribution of induced polarization charge at the solute-solvent dielectric interface. The solution of Poisson`s equation is obtained by application of a boundary element procedure. The method is tested by comparing its predictions of {Delta}G{sup el} to exact values for several model problems. The method is then used in a variety of contexts to assess its qualitative prediction ability. It is first combined with a molecular mechanics treatment of the solute to evaluate the effects of aqueous solvent on the conformational equilibria of several small molecules of interest-these are N-methyl acetamide and alanine dipeptide. For both molecules dielectric continuum solvation predicts torsional free energies of solvation that are in accord with other more complete treatments of solvation. The method is then combined with ab initio and semi-empirical molecular orbital theory for the solute. Self consistent reaction field calculations (SCRF) are performed to evaluate the correlation is in general very good. Relative agreement with experiment is best for ions where electrostatics predominate and worst for non-polar neutral molecules were electrostatics are minor. Semi-empirical configuration interaction SCRF calculations are also performed in the presence of solvent in order to determine ground-to-excited state absorption energy shifts for formaldehyde and indole mine ground-to-excited state absorption energy shifts for formaldehyde and indole when placed in water. We find a rough correlation between transition energy shifts and the dipole moments of the initial and final states involved in the transition.
Joseph Ivanic; Gregory J. Atchity; Klaus Ruedenberg
2007-02-12
A coherent, intrinsic, basis-set-independent analysis is developed for the invariants of the first-order density matrix of an accurate molecular electronic wavefunction. From the hierarchical ordering of the natural orbitals, the zeroth-order orbital space is deduced, which generates the zeroth-order wavefunction, typically an MCSCF function in the full valence space. It is shown that intrinsically embedded in such wavefunctions are elements that are local in bond regions and elements that are local in atomic regions. Basis-set-independent methods are given that extract and exhibit the intrinsic bond orbitals and the intrinsic minimal-basis quasi-atomic orbitals in terms of which the wavefunction can be exactly constructed. The quasi-atomic orbitals are furthermore oriented by a basis-set independent method (viz. maximization of the sum of the fourth powers of all off-diagonal density matrix elements) so as to exhibit clearly the chemical interactions. The unbiased nature of the method allows for the adaptation of the localized and directed orbitals to changing geometries.
NASA Astrophysics Data System (ADS)
Ishihara, Mariko; Sakagami, Hiroshi; Kawase, Masami; Motohashi, Noboru
The relationship between the cytotoxicity of N-heterocycles (13 4-trifluoromethylimidazole, 15 phenoxazine and 12 5-trifluoromethyloxazole derivatives), O-heterocycles (11 3-formylchromone and 20 coumarin derivatives) and seven vitamin K2 derivatives against eight tumor cell lines (HSC-2, HSC-3, HSC-4, T98G, HSG, HepG2, HL-60, MT-4) and a maximum of 15 chemical descriptors was investigated using CAChe Worksystem 4.9 project reader. After determination of the conformation of these compounds and approximation to the molecular form present in vivo (biomimetic) by CONFLEX5, the most stable structure was determined by CAChe Worksystem 4.9 MOPAC (PM3). The present study demonstrates the best relationship between the cytotoxic activity and molecular shape or molecular weight of these compounds. Their biological activities can be estimated by hardness and softness, and by using ?-? activity diagrams.
NASA Astrophysics Data System (ADS)
Mahalakshmi, G.; Balachandran, V.
2014-10-01
The FT-IR and FT-Raman spectra of 4-Aminomethylpiperidine have been recorded using Perkin Elmer Spectrophotometer and Nexus 670 spectrophotometer. The equilibrium geometrical parameters, various bonding features, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated using Hartree-Fock and density functional method (B3LYP) with 6-311+G(d,p) basis set. Detailed interpretations of the vibrational spectra have been carried out with the aid of the normal coordinate analysis. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of intra molecular hydrogen bonds, electron delocalization and steric effects. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of 4-Aminomethylpiperidine (4AMP) were calculated. The theoretical UV-Visible spectrum of the compound was computed in the region 200-400 nm by time-dependent TD-DFT approach. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (?) and polarizability (?), anisotropy polarizability (??) and hyperpolarizability (?) of the molecule have been reported.
Nakata, Hiroya; Fedorov, Dmitri G; Zahariev, Federico; Schmidt, Michael W; Kitaura, Kazuo; Gordon, Mark S; Nakamura, Shinichiro
2015-03-28
Analytic second derivatives of the energy with respect to nuclear coordinates have been developed for spin restricted density functional theory (DFT) based on the fragment molecular orbital method (FMO). The derivations were carried out for the three-body expansion (FMO3), and the two-body expressions can be obtained by neglecting the three-body corrections. Also, the restricted Hartree-Fock (RHF) Hessian for FMO3 can be obtained by neglecting the density-functional related terms. In both the FMO-RHF and FMO-DFT Hessians, certain terms with small magnitudes are neglected for computational efficiency. The accuracy of the FMO-DFT Hessian in terms of the Gibbs free energy is evaluated for a set of polypeptides and water clusters and found to be within 1 kcal/mol of the corresponding full (non-fragmented) ab initio calculation. The FMO-DFT method is also applied to transition states in SN2 reactions and for the computation of the IR and Raman spectra of a small Trp-cage protein (PDB: 1L2Y). Some computational timing analysis is also presented. PMID:25833559
NASA Astrophysics Data System (ADS)
Nakata, Hiroya; Fedorov, Dmitri G.; Zahariev, Federico; Schmidt, Michael W.; Kitaura, Kazuo; Gordon, Mark S.; Nakamura, Shinichiro
2015-03-01
Analytic second derivatives of the energy with respect to nuclear coordinates have been developed for spin restricted density functional theory (DFT) based on the fragment molecular orbital method (FMO). The derivations were carried out for the three-body expansion (FMO3), and the two-body expressions can be obtained by neglecting the three-body corrections. Also, the restricted Hartree-Fock (RHF) Hessian for FMO3 can be obtained by neglecting the density-functional related terms. In both the FMO-RHF and FMO-DFT Hessians, certain terms with small magnitudes are neglected for computational efficiency. The accuracy of the FMO-DFT Hessian in terms of the Gibbs free energy is evaluated for a set of polypeptides and water clusters and found to be within 1 kcal/mol of the corresponding full (non-fragmented) ab initio calculation. The FMO-DFT method is also applied to transition states in SN2 reactions and for the computation of the IR and Raman spectra of a small Trp-cage protein (PDB: 1L2Y). Some computational timing analysis is also presented.
Fedorov, Dmitri G; Ishimura, Kazuya; Ishida, Toyokazu; Kitaura, Kazuo; Pulay, Peter; Nagase, Shigeru
2007-07-15
The three-body energy expansion in the fragment molecular orbital method (FMO) was applied to the 2nd order Møller-Plesset theory (MP2). The accuracy of both the two and three-body expansions was determined for water clusters, alanine n-mers (alpha-helices and beta-strands) and one synthetic protein, using the 6-31G* and 6-311G* basis sets. At the best level of theory (three-body, two molecules/residues per fragment), the absolute errors in energy relative to ab initio MP2 were at most 1.2 and 5.0 mhartree, for the 6-31G* and 6-311G* basis sets, respectively. The relative accuracy was at worst 99.996% and 99.96%, for 6-31G* and 6-311G*, respectively. A three-body approximation was introduced and the optimum threshold value was determined. The protein calculation (6-31G*) at the production level (FMO2/2) took 3 h on 36 3.2-GHz Pentium 4 nodes and had the absolute error in the MP2 correlation energy of only 2 kcal/mol. PMID:17330884
Hitaoka, Seiji; Chuman, Hiroshi; Yoshizawa, Kazunari
2015-01-21
A binding mechanism between human matrix metalloproteinase-12 (MMP-12) and eight arylsulfone analogs having two types of carboxylic and hydroxamic acids as the most representative zinc binding group is investigated using a quantitative structure-activity relationship (QSAR) analysis based on a linear expression by representative energy terms (LERE). The LERE-QSAR analysis quantitatively reveals that the variation in the observed (experimental) inhibitory potency among the arylsulfone analogs is decisively governed by those in the intrinsic binding and dispersion interaction energies. The results show that the LERE-QSAR analysis not only can excellently reproduce the observed overall free-energy change but also can determine the contributions of representative free-energy changes. An inter-fragment interaction energy difference (IFIED) analysis based on the fragment molecular orbital (FMO) method (FMO-IFIED) leads to the identification of key residues governing the variation in the inhibitory potency as well as to the understanding of the difference between the interactions of the carboxylic and hydroxamic acid zinc binding groups. The current results that have led to the optimization of the inhibitory potency of arylsulfone analogs toward MMP-12 to be used in the treatment of chronic obstructive pulmonary disease may be useful for the development of a new potent MMP-12 inhibitor. PMID:25406681
Mahalakshmi, G; Balachandran, V
2014-10-15
The FT-IR and FT-Raman spectra of 4-Aminomethylpiperidine have been recorded using Perkin Elmer Spectrophotometer and Nexus 670 spectrophotometer. The equilibrium geometrical parameters, various bonding features, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated using Hartree-Fock and density functional method (B3LYP) with 6-311+G(d,p) basis set. Detailed interpretations of the vibrational spectra have been carried out with the aid of the normal coordinate analysis. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of intra molecular hydrogen bonds, electron delocalization and steric effects. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of 4-Aminomethylpiperidine (4AMP) were calculated. The theoretical UV-Visible spectrum of the compound was computed in the region 200-400nm by time-dependent TD-DFT approach. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (?) and polarizability (?), anisotropy polarizability (??) and hyperpolarizability (?) of the molecule have been reported. PMID:24853994
NASA Astrophysics Data System (ADS)
Yang, Wen-Hui; Schatz, George C.
1992-09-01
Ab initio and semiempirical molecular orbital methods have been used to calculate the bulk and surface Raman and hyperRaman spectra of pyridine. Similar calculations for benzene are also reported. For both molecules, we compare the results with available bulk and surface experiments. In all calculations, the polarizability and hyperpolarizability derivatives are evaluated using normal coordinates that are obtained from Hartree-Fock (HF) calculations. The Raman results are somewhat sensitive to the basis set used in determining the normal coordinates, and the hyper-Raman spectra are strongly sensitive. The Raman and hyper-Raman spectra have been calculated at zero frequency using HF methods (GAUSSIAN 90), and finite frequency using INDO (intermediate neglect of differential overlap) methods (zindo). The frequency dependence of the results is found to be minor. Comparisons with experiment indicate that the inclusion of diffuse basis functions is crucial to the accuracy of the HF calculations. For such basis sets, the benzene Raman and hyper-Raman spectra provided by HF are in excellent agreement with experiment. Raman spectra from HF for pyridine also agree well, but hyper-Raman spectra agree only in part. Changes in Raman and hyper-Raman spectra calculated in going from bulk to surface generally agree with observations. The corresponding bulk and surface spectra from zindo are usually less accurate, especially the hyper-Raman spectra, and especially the out of plane modes. Estimates of the surface hyper-Raman enhancement factor are in the range 1011-1012 for pyridine on silver electrodes.
NASA Astrophysics Data System (ADS)
Bäppler, Stefanie A.; Plasser, Felix; Wormit, Michael; Dreuw, Andreas
2014-11-01
Exciton sizes and electron-hole binding energies, which are central properties of excited states in extended systems and crucial to the design of modern electronic devices, are readily defined within a quasiparticle framework but are quite challenging to understand in the molecular-orbital picture. The intent of this work is to bridge this gap by providing a general way of extracting the exciton wave function out of a many-body wave function obtained by a quantum chemical excited-state computation. This methodology, which is based on the one-particle transition density matrix, is implemented within the ab initio algebraic diagrammatic construction scheme for the polarization propagator and specifically the evaluation of exciton sizes, i.e., dynamic charge separation distances, is considered. A number of examples are presented. For stacked dimers it is shown that the exciton size for charge separated states corresponds to the intermolecular separation, while it only depends on the monomer size for locally excited states or Frenkel excitons. In the case of conjugated organic polymers, the tool is applied to analyze exciton structure and dynamic charge separation. Furthermore, it is discussed how the methodology may be used for the construction of a charge-transfer diagnostic for time-dependent density-functional theory.
Xiao-Hong, Li; Hong-Ling, Cui; Rui-Zhou, Zhang; Xian-Zhou, Zhang
2015-02-25
The vibrational frequencies of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide (HB-CA) in the ground state have been calculated using density functional method (B3LYP) with B3LYP/6-311++G(d,p) basis set. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exists C-H?O hydrogen bond in the title compound, which is confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as nonlinear optical material. The analysis of frontier molecular orbitals shows that HB-CA has high excitation energies, good stability and high chemical hardness. The analysis of MEP map shows the negative and the positive potential sites. PMID:25228040
Lombardi, James C
2015-01-01
In a previous investigation, the orbital radii of regular satellites of Uranus, Jupiter, Neptune, and Saturn are shown to be directly related to photon energies in the spectra of atomic and molecular hydrogen. To explain these observations a model was developed involving stimulated radiative molecular association (SRMA) reactions among photons and atoms in the protosatellite disks of the planets. In the present investigation, the previously developed model is applied to the planets and important satellites of the Sun. A key component of the model involves resonance associated with SRMA. Through this resonance, thermal energy is extracted from the protosun's protoplanetary disk at specific distances from the protosun wherever there is a match between the local thermal energy of the disk and the energy of photons impinging on the disk. Orbital radii of the planets and satellites are related to photon energies ($E_P$ values) in the spectrum of atomic hydrogen. An expression determined previously is used to relat...
Jin, Cheng; Le, Anh-Thu; Lin, C. D.
2011-05-15
We report theoretical calculations of the effect of the multiple-orbital contribution in high-order harmonic generation (HHG) of aligned CO{sub 2} with the inclusion of macroscopic propagation of harmonic fields in the medium. Our results show very good agreement with recent experiments for the dynamics of the minimum in HHG spectra as laser intensity or alignment angle changes. Calculations are carried out to check how the position of the minimum in HHG spectra depends on the degrees of molecular alignment, laser-focusing conditions, and the effects of alignment-dependent ionization rates of the different molecular orbitals. These analyses help to explain why the minima observed in different experiments may vary.
Subramaniam, Anandh
PHASE DIAGRAMS Phase Rule Types of Phase diagrams Lever Rule Alloy Phase Equilibria A. Prince Elsevier Publishing Company, Amsterdam (1966) Advanced Reading EQUILIBRIUM PHASE DIAGRAMS #12; Phase diagrams are an important tool in the armory of an materials scientist In the simplest sense a phase
Rough Diagrams Laurent Vigneron
Vigneron, Laurent
Rough Diagrams Laurent Vigneron LORIA { Universit#19;e Nancy 2, Campus Scienti#12;que, B.P. 239 used for proving important properties of rough Boolean algebras, combining theorem provers with a graphical technique, called Rough Diagrams. Rough Diagrams correspond to a classical notion of Ven Diagrams
NASA Astrophysics Data System (ADS)
Zhou, H. T.; Mao, J. H.; Li, G.; Wang, Y. L.; Feng, X. L.; Du, S. X.; Müllen, K.; Gao, H.-J.
2011-10-01
Using epitaxially grown graphene on Ru(0001) as a buffer layer, the intrinsic molecular orbitals of perylene-3,4,9,10-tetracarboxylic dianhydride, pentacene, and C60 molecules were imaged by means of scanning tunneling microscope (STM). Combined with density functional theory calculations, our high resolution STM images of the molecules reveal that the graphene layer decouples the individual molecules electronically from the metallic substrate. Our results show that graphene-based moiré pattern can be used as a unique way to probe the intrinsic electronic structures of molecular adsorbates and their interactions.
M. A. Warne; D. Osborn; J. C. Lindon; J. K. Nicholson
1999-01-01
Quantitative structure-toxicity relationships (QSTR's) are derived for an extensive series of halogenated benzenes, anilines, phenols, nitrobenzenes, toluenes and other substituted benzenes against Vibrio fischeri using a wide range of whole molecule and atom-based descriptors derived from semi-empirical molecular-orbital calculations. In terms of direct statistical correlation with toxicity it was found that the molar refractivity was the most important parameter, closely
1978-01-01
The use of ab initio molecular orbital calculations to aid in the characterization, i.e., structures and energies, of metal halide complexes present in high temperature salt vapors has been investigated. Standard LCAO-SCF methods were used and calculations were carried out using the minimal STO-3G basis set. The complexes included in this study were AlâFâ, AlâClâ, AlFâ NHâ, AlClâ NHâ, and
Moreira, Rodrigo A.; Melo, Celso P. de, E-mail: celso@df.ufpe.br [Departamento de Física, Universidade Federal de Pernambuco, Recife-PE 50670-901 (Brazil)
2014-09-28
Based on a quantum chemical valence formalism that allows the rigorous construction of best-localized molecular orbitals on specific parts of an extended system, we examined the separability of individual components of model systems relevant to the description of electron transport in molecular devices. We started by examining how to construct the maximally localized electronic density at the tip of a realistic model of a gold electrode. By varying the number of gold atoms included in the local region where to project the total electronic density, we quantitatively assess how many molecular orbitals are entirely localized in that region. We then considered a 1,4-benzene-di-thiol molecule connected to two model gold electrodes and examined how to localize the electronic density of the total system in the extended molecule, a fractional entity comprising the organic molecule plus an increasing number of the closest metal atoms. We were able to identify in a rigorous manner the existence of three physically different electronic populations, each one corresponding to a distinct set of molecular orbitals. First, there are those entirely localized in the extended molecule, then there is a second group of those completely distributed in the gold atoms external to that region, and, finally, there are those delocalized over the entire system. This latter group can be associated to the shared electronic population between the extended molecule and the rest of the system. We suggest that the treatment here presented could be useful in the theoretical analysis of the electronic transport in nanodevices whenever the use of localized molecular states are required by the physics of the specific problem, such as in cases of weak coupling and super-exchange limits.
Hilary R. Martens; D. B. Reisenfeld; J. D. Williams; J. DiLorenzo; M. F. Thomsen; H. T. Smith; A. Eviatar; R. E. Johnson; D. T. Young; E. C. Sittler; R. A. Baragiola
2006-01-01
We present magnetospheric ion composition results from the Cassini Plasma Spectrometer (CAPS) for the first 24 orbits of Cassini about Saturn. Apoapses of these orbits have local times between 3 and 8 MLT. Data from the Ion Mass Spectrometer (IMS) are summed to achieve better statistics and to bring out features that are otherwise difficult to resolve from an individual
NASA Astrophysics Data System (ADS)
Shan, Xu; Xu, Chun-kai; Yin, Xiao-feng; Zhou, Li-xia; Xu, Ke-zun; Chen, Xiang-jun
2009-12-01
Electron momentum distributions for 4a1 orbitals of serial freon molecules CF3Cl, CF2Cl2, and CFCl3 (CFxCl4-x, x = 1-3) have been reanalyzed due to the severe discrepancies between theory and experiment in low momentum region. The tentative calculations using equilibrium geometries of molecular ions have exhibited a great improvement in agreement with the experimental data, which suggests that the molecular geometry distortion may be responsible for the observed high intensities at p < 0.5 a.u. Further analyses show that the severe discrepancies at low momentum region mainly arise from the influence of molecular geometry distortion on C-Cl bonding electron density distributions.
Taha, Ali
2003-04-01
Solvatochromic mixed ligand complexes of copper(II) with malonate and diamine derivatives, Cu(n)(RMal)(diam)(n)X(m) (where n=1 or 2, m=1-4, RMal, malonic acid (H(2)Mal), diethylmalonate (HDEtMal) or diethylethoxyethylenemalonate (DEtEMal), and diam, ethylenediamine (en), 1,3-propylenediamine (1,3-pn), N,N,N'-trimethylethylenediamine (Me(3)en), N,N,N'-triethylethylenediamine (Et(3)en), N,N,N',N'-tetramethylethylenediamine (Me(4)en), N,N,N',N'-tetramethylpropylenediamine (Me(4)pn), or N-methyl-1,4-diazacycloheptane (medach); and X=ClO(4)(-) or Cl(-)), has been synthesized and characterized by spectroscopic, magnetic, molar conductance and electrochemical measurements. The mass spectra along with the analytical data of the complexes show peaks with m/e corresponding to a bridged binuclear structure for the chloride complexes, while perchlorate complexes showed either mononuclear structure for DEtMal and DEtEMal or bridged binuclear structure for Mal complexes. These results correspond to IR spectral data, which indicated that the modes of ester and carboxylato coordination sites are mono- and/or bidentate. The d-d absorption bands in weak donor solvents suggest square-planar and distorted square pyramidal-trigonal bipyramid geometries for the perchlorate and chloride complexes; respectively. On the other hand, an octahedral structure is identified for complexes in strong donor solvents. Perchlorate complexes show a drastic color change from violet to green as the donation ability of solvent increases, whereas chloride complexes are highly affected by the acceptor properties of the solvent. Cyclic voltammetric measurements on the complexes, proposed a quasi-reversible or irreversible and mainly diffusion controlled reduction process. Such behavior has been explained according to the ECE mechanism. A linear correlation has been found between the Cu(II) reduction potential and the spectral data. Molecular orbital calculations were performed for the ligands on the bases of PM3 level and the results corresponded to the experimental data. The data are discussed in terms of chromotropic concept and its applications as a Lewis acid-base color indicator. PMID:12659906
NASA Astrophysics Data System (ADS)
Zhu, X. L.; Zeng, X. C.; Lei, Y. A.; Pan, B.
2004-05-01
Ab initio all-electron molecular-orbital calculations are carried out to study the structures and relative stability of low-energy silicon clusters (Sin,n=12-20). Selected geometric isomers include those predicted by Ho et al. [Nature (London) 392, 582 (1998)] based on an unbiased search with tight-binding/genetic algorithm, as well as those found by Rata et al. [Phys. Rev. Lett. 85, 546 (2000)] based on density-functional tight-binding/single-parent evolution algorithm. These geometric isomers are optimized at the Møller-Plesset (MP2) MP2/6-31G(d) level. The single-point energy at the coupled-cluster single and double substitutions (including triple excitations) [CCSD(T)] CCSD(T)/6-31G(d) level for several low-lying isomers are further computed. Harmonic vibrational frequency analysis at the MP2/6-31G(d) level of theory is also undertaken to assure that the optimized geometries are stable. For Si12-Si17 and Si19 the isomer with the lowest-energy at the CCSD(T)/6-31G(d) level is the same as that predicted by Ho et al., whereas for Si18 and Si20, the same as predicted by Rata et al. However, for Si14 and Si15, the vibrational frequency analysis indicates that the isomer with the lowest CCSD(T)/6-31G(d) single-point energy gives rise to imaginary frequencies. Small structural perturbation onto the Si14 and Si15 isomers can remove the imaginary frequencies and results in new isomers with slightly lower MP2/6-31G(d) energy; however the new isomers have a higher single-point energy at the CCSD(T)/6-31G(d) level. For most Sin (n=12-18,20) the low-lying isomers are prolate in shape, whereas for Si19 a spherical-like isomer is slightly lower in energy at the CCSD(T)/6-31G(d) level than low-lying prolate isomers.
NSDL National Science Digital Library
Dexter Perkins
This exercise should be used after you think students know what AFM diagrams are and how they work. This is sort of a quiz - to see if they can properly interpret the diagrams. There is no point moving on to real projects that involve AFM diagrams if the students don't understand the basics.
ERIC Educational Resources Information Center
Kimmins, Dovie L.; Winters, J. Jeremy
2015-01-01
Two perspectives of the term "Venn diagram" reflect the typical differences in the uses of Venn diagrams in the subject areas of mathematics and language arts. These differences are subtle; nevertheless, they can potentially be confusing. In language arts, the circles in a Venn diagram typically represent things that can be compared and…
NASA Astrophysics Data System (ADS)
Barfield, Michael; Babaqi, Abdulla S.; Doddrell, David M.; Gottlieb, Hans P. W.
The anisotropic hyperfine coupling constants (AHCC) from the electron spin resonance (E.S.R.) spectra of a variety of atoms in organic radicals have been calculated by means of semiempirical molecular orbital wavefunctions in the INDO approximation. Hyperfine tensors involving 1H, 13C and 19F nuclei are obtained for the ?H, ?H3, CH3?H2, (CH3)3? hydrocarbon radicals, malonic acid radical, ?H2F, ?F2H, ?F3 and CF3?H2 radicals. The calculated values are compared with available experimental, non-empirical and semiempirical values for these radicals. All integrals of the operator entering the electronic contributions have been evaluated over Slater type orbitals. The introduction of deorthogonalized wavefunctions gives generally better calculated results. In particular, the tensor components of the 19F AHCC are in good agreement with the experimental results without the necessity of readjusting the effective nuclear charges.
NASA Astrophysics Data System (ADS)
Zahedi, Ehsan
2015-05-01
The conductance and electronic transport properties of a single-molecular diode with one backbone ( 1), and two backbones in parallel ( 2) have been investigated using frontier orbital analysis, and the NEGF formalism combined with DFT. The frontier orbital analysis results demonstrate that the electron transport from one end of the studied molecules to other end is symmetrically allowed and the conductance of the molecule with two parallel backbones is more than the molecule with a single backbone. Transmission spectra study based on the NEGF-DFT of the selected molecules sandwiched between two gold (1 1 1) electrodes showed that, due to a higher coupling between the two electrodes and the molecule 2, the zero-bias conductance is more than twice that of the other molecular junction. Transmission spectra under different biases showed that the maximum constructive interference exists at the bias voltage 0.2, while in some of the biases destructive effects are observed. I- V curves showed that the rectifying directions of molecular junctions 1 and 2 are opposite.
Danel, J-F; Kazandjian, L
2015-01-01
We test two isothermal-isobaric mixing rules, respectively based on excess-pressure and total-pressure equilibration, applied to the equation of state of a dense plasma. While the equation of state is generally known for pure species, that of arbitrary mixtures is not available so that the validation of accurate mixing rules, that implies resorting to first-principles simulations, is very useful. Here we consider the case of a plastic with composition C(2)H(3) and we implement two complementary ab initio approaches adapted to the dense plasma domain: quantum molecular dynamics, limited to low temperature by its computational cost, and orbital-free molecular dynamics, that can be implemented at high temperature. The temperature and density range considered is 1-10 eV and 0.6-10 g/cm(3) for quantum molecular dynamics, and 5-1000 eV and 1-10 g/cm(3) for orbital-free molecular dynamics. Simulations for the full C(2)H(3) mixture are the benchmark against which to assess the mixing rules, and both pressure and internal energy are compared. We find that the mixing rule based on excess-pressure equilibration is overall more accurate than that based on total-pressure equilibration; except for quantum molecular dynamics and a thermodynamic domain characterized by very low or negative excess pressures, it gives pressures which are generally within statistical error or within 1% of the exact ones. Besides, its superiority is amplified in the calculation of a principal Hugoniot. PMID:25679719
NASA Astrophysics Data System (ADS)
Danel, J.-F.; Kazandjian, L.
2015-01-01
We test two isothermal-isobaric mixing rules, respectively based on excess-pressure and total-pressure equilibration, applied to the equation of state of a dense plasma. While the equation of state is generally known for pure species, that of arbitrary mixtures is not available so that the validation of accurate mixing rules, that implies resorting to first-principles simulations, is very useful. Here we consider the case of a plastic with composition C2H3 and we implement two complementary ab initio approaches adapted to the dense plasma domain: quantum molecular dynamics, limited to low temperature by its computational cost, and orbital-free molecular dynamics, that can be implemented at high temperature. The temperature and density range considered is 1-10 eV and 0.6-10 g/cm 3 for quantum molecular dynamics, and 5-1000 eV and 1-10 g/cm 3 for orbital-free molecular dynamics. Simulations for the full C2H3 mixture are the benchmark against which to assess the mixing rules, and both pressure and internal energy are compared. We find that the mixing rule based on excess-pressure equilibration is overall more accurate than that based on total-pressure equilibration; except for quantum molecular dynamics and a thermodynamic domain characterized by very low or negative excess pressures, it gives pressures which are generally within statistical error or within 1% of the exact ones. Besides, its superiority is amplified in the calculation of a principal Hugoniot.
Phase Equilibria Diagrams Database
National Institute of Standards and Technology Data Gateway
SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase) The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.
NASA Astrophysics Data System (ADS)
Kawakami, T.; Takeda, R.; Nishihara, S.; Saito, T.; Shoji, M.; Yamada, S.; Yamanaka, S.; Kitagawa, Y.; Okumura, M.; Yamaguchi, K.
2009-11-01
Symmetry and broken symmetry in the molecular orbital description of spin frustration systems have been investigated in relation to the resonating valence bond (RVB) theory of the spin liquid state and non-BCS superconductivity. Broken symmetry (BS) and resonating BS (RBS) molecular orbital (MO) methods have been employed to obtain resonating valence bond (RVB)-type explanations of spin frustrated systems. RBS MO solutions are expanded using the localized molecular orbitals (LMO) to elucidate a universal MO-VB description. The BS and RBS MO descriptions of triangular spin frustrated systems corresponding to transition structures for exchange-forbidden radical insertions were investigated in comparison with the RVB-type explanations of such systems. The BS and RBS calculations by the use of three different axial (SDW) solutions or three noncollinear GSO (helical SDW) solutions of a triangular hydrogen cluster were performed to obtain potential curves with and without resonance (quantum) effects. The resonating GSO (noncollinear) state responsible for short-range correlation was found to be the most stable for the system. The reliability of the approximate spin projection (AP) procedure to eliminate the high-spin component was also elucidated, comparing with the AP BS and RBS potential curves. The BS GSO (GHF) computations of several triangular systems, N(CH2)3, (CH2)3, and Mn(II)3O4, were performed to obtain total energies and total spin angular momentums and effective exchange integrals (J) between local spins, which are crucial for construction of effective spin Hamiltonian models. The exact diagonalization of the Heisenberg models was also performed to depict the energy levels and magnetic susceptibility curves for triangular and kagome lattices to elucidate spin frustration effects and related quantum spin behaviors. Implications of the computational results have been discussed in relation to magnetic properties of several triangular and kagome systems synthesized recently and the superconductivity of triangular systems discovered recently.
Kawakami, T; Takeda, R; Nishihara, S; Saito, T; Shoji, M; Yamada, S; Yamanaka, S; Kitagawa, Y; Okumura, M; Yamaguchi, K
2009-12-31
Symmetry and broken symmetry in the molecular orbital description of spin frustration systems have been investigated in relation to the resonating valence bond (RVB) theory of the spin liquid state and non-BCS superconductivity. Broken symmetry (BS) and resonating BS (RBS) molecular orbital (MO) methods have been employed to obtain resonating valence bond (RVB)-type explanations of spin frustrated systems. RBS MO solutions are expanded using the localized molecular orbitals (LMO) to elucidate a universal MO-VB description. The BS and RBS MO descriptions of triangular spin frustrated systems corresponding to transition structures for exchange-forbidden radical insertions were investigated in comparison with the RVB-type explanations of such systems. The BS and RBS calculations by the use of three different axial (SDW) solutions or three noncollinear GSO (helical SDW) solutions of a triangular hydrogen cluster were performed to obtain potential curves with and without resonance (quantum) effects. The resonating GSO (noncollinear) state responsible for short-range correlation was found to be the most stable for the system. The reliability of the approximate spin projection (AP) procedure to eliminate the high-spin component was also elucidated, comparing with the AP BS and RBS potential curves. The BS GSO (GHF) computations of several triangular systems, N(CH(2))(3), (CH(2))(3), and Mn(II)(3)O(4), were performed to obtain total energies and total spin angular momentums and effective exchange integrals (J) between local spins, which are crucial for construction of effective spin Hamiltonian models. The exact diagonalization of the Heisenberg models was also performed to depict the energy levels and magnetic susceptibility curves for triangular and kagome lattices to elucidate spin frustration effects and related quantum spin behaviors. Implications of the computational results have been discussed in relation to magnetic properties of several triangular and kagome systems synthesized recently and the superconductivity of triangular systems discovered recently. PMID:19908878
Ferenczy, György G
2013-04-01
The application of the local basis equation (Ferenczy and Adams, J. Chem. Phys. 2009, 130, 134108) in mixed quantum mechanics/molecular mechanics (QM/MM) and quantum mechanics/quantum mechanics (QM/QM) methods is investigated. This equation is suitable to derive local basis nonorthogonal orbitals that minimize the energy of the system and it exhibits good convergence properties in a self-consistent field solution. These features make the equation appropriate to be used in mixed QM/MM and QM/QM methods to optimize orbitals in the field of frozen localized orbitals connecting the subsystems. Calculations performed for several properties in divers systems show that the method is robust with various choices of the frozen orbitals and frontier atom properties. With appropriate basis set assignment, it gives results equivalent with those of a related approach [G. G. Ferenczy previous paper in this issue] using the Huzinaga equation. Thus, the local basis equation can be used in mixed QM/MM methods with small size quantum subsystems to calculate properties in good agreement with reference Hartree-Fock-Roothaan results. It is shown that bond charges are not necessary when the local basis equation is applied, although they are required for the self-consistent field solution of the Huzinaga equation based method. Conversely, the deformation of the wave-function near to the boundary is observed without bond charges and this has a significant effect on deprotonation energies but a less pronounced effect when the total charge of the system is conserved. The local basis equation can also be used to define a two layer quantum system with nonorthogonal localized orbitals surrounding the central delocalized quantum subsystem. PMID:23288700
Ferenczy, György G
2013-04-01
Mixed quantum mechanics/quantum mechanics (QM/QM) and quantum mechanics/molecular mechanics (QM/MM) methods make computations feasible for extended chemical systems by separating them into subsystems that are treated at different level of sophistication. In many applications, the subsystems are covalently bound and the use of frozen localized orbitals at the boundary is a possible way to separate the subsystems and to ensure a sensible description of the electronic structure near to the boundary. A complication in these methods is that orthogonality between optimized and frozen orbitals has to be warranted and this is usually achieved by an explicit orthogonalization of the basis set to the frozen orbitals. An alternative to this approach is proposed by calculating the wave-function from the Huzinaga equation that guaranties orthogonality to the frozen orbitals without basis set orthogonalization. The theoretical background and the practical aspects of the application of the Huzinaga equation in mixed methods are discussed. Forces have been derived to perform geometry optimization with wave-functions from the Huzinaga equation. Various properties have been calculated by applying the Huzinaga equation for the central QM subsystem, representing the environment by point charges and using frozen strictly localized orbitals to connect the subsystems. It is shown that a two to three bond separation of the chemical or physical event from the frozen bonds allows a very good reproduction (typically around 1 kcal/mol) of standard Hartree-Fock-Roothaan results. The proposed scheme provides an appropriate framework for mixed QM/QM and QM/MM methods. PMID:23281055
NASA Astrophysics Data System (ADS)
Nakata, Hiroya; Fedorov, Dmitri G.; Yokojima, Satoshi; Kitaura, Kazuo; Sakurai, Minoru; Nakamura, Shinichiro
2014-04-01
We extended the fragment molecular orbital (FMO) method interfaced with density functional theory (DFT) into spin unrestricted formalism (UDFT) and developed energy gradients for the ground state and single point excited state energies based on time-dependent DFT. The accuracy of FMO is evaluated in comparison to the full calculations without fragmentation. Electronic excitations in solvated organic radicals and in the blue copper protein, plastocyanin (PDB code: 1BXV), are reported. The contributions of solvent molecules to the electronic excitations are analyzed in terms of the fragment polarization and quantum effects such as interfragment charge transfer.
Nakata, Hiroya, E-mail: nakata.h.ab@m.titech.ac.jp [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan) [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Fedorov, Dmitri G. [NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Yokojima, Satoshi [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan) [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tokyo University of Pharmacy and Life Sciences, 1423-1 Horinouchi, Hachioji-shi, Tokyo 192-0392 (Japan); Kitaura, Kazuo [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)] [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Sakurai, Minoru [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan)] [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); Nakamura, Shinichiro [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)] [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2014-04-14
We extended the fragment molecular orbital (FMO) method interfaced with density functional theory (DFT) into spin unrestricted formalism (UDFT) and developed energy gradients for the ground state and single point excited state energies based on time-dependent DFT. The accuracy of FMO is evaluated in comparison to the full calculations without fragmentation. Electronic excitations in solvated organic radicals and in the blue copper protein, plastocyanin (PDB code: 1BXV), are reported. The contributions of solvent molecules to the electronic excitations are analyzed in terms of the fragment polarization and quantum effects such as interfragment charge transfer.
Burakovsky, Leonid; Kress, Joel D.; Collins, Lee A.
2012-05-31
Mass transport properties for LiD-U mixtures were calculated using a pressure matching mixture rule for the mixing of LiD and of U properties simulated with Orbital Free Molecular Dynamics (OFMD). The mixing rule was checked against benchmark OFMD simulations for the fully interacting three-component (Li, D, U) system. To obtain transport coefficients for LiD-U mixtures of different (LiD){sub x}U{sub (1-x)} compositions as functions of temperature and mixture density is a tedious task. Quantum molecular dynamics (MD) simulations can be employed, as in the case LiD or U. However, due to the presence of the heavy constituent U, such simulations proceed so slowly that only a limited number of numerical data points in the (x, {rho}, T) phase space can be obtained. To finesse this difficulty, transport coefficients for a mixture can be obtained using a pressure-matching mixing rule discussed. For both LiD and U, the corresponding transport coefficients were obtained earlier from quantum molecular dynamics simulations. In these simulations, the quantum behavior of the electrons was represented using an orbital free (OF) version of density functional theory, and ions were advanced in time using classical molecular dynamics. The total pressure of the system, P = nk{sub B}T/V + P{sub e}, is the sum of the ideal gas pressure of the ions plus the electron pressure. The mass self-diffusion coefficient for species {alpha}, D{sub {alpha}}, the mutual diffusion coefficient for species {alpha} and {beta}, D{alpha}{beta}, and the shear viscosity, {eta}, are computed from the appropriate autocorrelation function. The details of similar QMD calculations on LiH are described in Ref. [1] for 0.5 eV < T < 3 eV, and in Ref. [2] for 2 eV < T < 6 eV.
Yu, Jenwei; Anderson, A.B. )
1990-09-26
Activation of the CH bond in CH{sub 4} and t-BuO(ads) by H{sup {sm bullet}} transfer to O adsorbed on the Ag(110) surface has been studied by the atom-superposition and electron-delocalization molecular orbital theory. Both abstractions are found to proceed with a low-energy barrier because of the presence of low-lying empty Ag surface orbitals at the Fermi level. Transfer of an electron to the Fermi level alleviates the initial closed-shell repulsion between the CH {sigma}-bond electron pair and the surface O (which is formally O{sup 2{minus}}) lone-pair orbital that ultimately forms the OH {sigma} bond. It is concluded that surface O behaves like a radical anion O{sup {sm bullet}{minus}} or R{sub 3}O{sup {sm bullet}} in its ability to form a single bond. These calculations also suggest the possibility that surface oxygen atoms might insert into CH bonds to form alcohols, which is a result of their ability to exhibit O atom or carbene (R{sub 2}C:) bonding properties.
Trifunovi?, Sre?ko R; Mileti?, Vesna D; Jevti?, Verica V; Meetsma, Auke; Matovi?, Zoran D
2013-10-01
The O-N-N-O-type tetradentate ligands H2S,S-eddp (H2S,S-eddp stands for S,S-ethylenediamine-N,N'-di-2-propionic acid) and H2edap (H2edap stands for ethylenediamine-N-acetic-N'-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. N2O2 ligands coordinate to the nickel(II) ion via four donor atoms (two deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in the case of all investigated Ni(II) complexes. A six coordinate, octahedral geometry has been verified crystallographically for the s-cis-[Ni(S,S-eddp)(H2O)2] complex. Structural data correlating similarly chelated Ni(II) complexes have been used to carry out an extensive configuration analysis. Molecular mechanics and Density Functional Theory (DFT) have been used to model the most stable geometric isomer, yielding, at the same time, significant structural and spectroscopic (TDDFT) data. The results from density functional studies have been compared to X-ray data. Natural Bond Orbital (NBO) and Natural Energetic Decomposition Analysis (NEDA) have been done for the [Ni(edda-type)(H2O)(2-n)] and nH2O fragments. Molecular orbital analysis (MPA) is given as well. The infra-red and electronic absorption spectra of the complexes are discussed in comparison to the related complexes of known geometries. PMID:23884426
NASA Astrophysics Data System (ADS)
Karnan, M.; Balachandran, V.; Murugan, M.
2012-10-01
The optimized molecular structure and corresponding vibrational assignments of 3-hydroxy-6-methyl-2-nitropyridine have been investigated using density functional theory (DFT) B3LYP method with 6-311++G(d,p), 6-311++G(2d,2p) and 6-311++G(3d,3p) basis sets. Investigation of the relative orientation of the hydroxyl group with respect to the nitro group has shown that two conformers (O-cis) and (O-trans) exist. The vibrational analysis of the stable conformer of the title compound is performed by means of infrared absorption and Raman spectroscopy in combination with theoretical simulations. The molecular stability and bond strength were investigated by applying the natural bond orbital (NBO) analysis. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with electrostatic potential (ESP). The isotropic chemical shift computed by 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the HMNP calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations.
Gwaltney, Steven R; Rosokha, Sergiy V; Head-Gordon, Martin; Kochi, Jay K
2003-03-19
The highly disparate rates of aromatic nitrosation and nitration, despite the very similar (electrophilic) properties of the active species: NO(+) and NO(2)(+) in Chart 1, are quantitatively reconciled. First, the thorough mappings of the potential-energy surfaces by high level (ab initio) molecular-orbital methodologies involving extensive coupled-cluster CCSD(T)/6-31G optimizations establish the intervention of two reactive intermediates in nitration (Figure 8) but only one in nitrosation (Figure 7). Second, the same distinctive topologies involving double and single potential-energy minima (Figures 6 and 5) also emerge from the semiquantitative application of the Marcus-Hush theory to the transient spectral data. Such a striking convergence from quite different theoretical approaches indicates that the molecular-orbital and Marcus-Hush (potential-energy) surfaces are conceptually interchangeable. In the resultant charge-transfer mechanism, the bimolecular interactions of arene donors with both NO(+) and NO(2)(+) spontaneously lead (barrierless) to pi-complexes in which electron transfer is concurrent with complexation. Such a pi-complex in nitration is rapidly converted to the sigma-complex, whereas this Wheland adduct in nitrosation merely represents a high energy (transition-state) structure. Marcus-Hush analysis thus demonstrates how the strongly differentiated (arene) reactivities toward NO(+) and NO(2)(+) can actually be exploited in the quantitative development of a single coherent (electron-transfer) mechanism for both aromatic nitrosation and nitration. PMID:12630883
NASA Astrophysics Data System (ADS)
Jung, Jaewoon; Sugita, Yuji; Ten-no, S.
2010-02-01
An analytic gradient expression is formulated and implemented for the second-order Møller-Plesset perturbation theory (MP2) based on the generalized hybrid orbital QM/MM method. The method enables us to obtain an accurate geometry at a reasonable computational cost. The performance of the method is assessed for various isomers of alanine dipepetide. We also compare the optimized structures of fumaramide-derived [2]rotaxane and cAMP-dependent protein kinase with experiment.
NASA Astrophysics Data System (ADS)
Chiosi, C.; Murdin, P.
2000-11-01
The Hertzsprung-Russell diagram (HR-diagram), pioneered independently by EJNAR HERTZSPRUNG and HENRY NORRIS RUSSELL, is a plot of the star luminosity versus the surface temperature. It stems from the basic relation for an object emitting thermal radiation as a black body: ...
Correlation of molecular valence- and K-shell photoionization resonances with bond lengths
NASA Technical Reports Server (NTRS)
Sheehy, J. A.; Gil, T. J.; Winstead, C. L.; Farren, R. E.; Langhoff, P. W.
1989-01-01
The relationship between the interatomic distance and the positions of valence-shell and K-shell sigma(asterisk) photoionization resonances is investigated theoretically for the molecules C2, F2, N2, O2, CO, NO, C2H2, C2H4, C2H6, HCN, H2CO, N20, CO2, and C2N2. The results of molecular-orbital computations are presented in three-dimensional diagrams, which are shown to be similar to the wave functions of a particle in a cylindrical well, confirming the validity of free-electron molecular-orbital (FEMO) approximations for modeling the potential along the symmetry axis. FEMO orbital energies and resonance positions are found to be in good agreement with previous theoretical and experimental results. Also included is a Feshbach-Fano analysis of the relevance of virtual-valence orbitals to the appearance of single-channel resonances in molecular photoionization cross sections.
Failure diagrams for unidirectional
NASA Astrophysics Data System (ADS)
Chan, K. S.
1993-07-01
Pertinent failure processes in unidirectional fiber metal-matrix composites (MMCs) have been identified and analyzed. The critical conditions for interface delamination in several composites are compared with the theoretical delamination diagram proposed by He and Hutchinson, in which interface delamination and fiber fracture are delineated on the basis of their relative tough-ness values. It is shown that the delamination diagram does not provide information about the extent of interface cracking or the onset of fiber bridging. An alternative failure diagram that depicts composite fracture processes, such as matrix yielding followed by fiber fracture, inter-face cracking, and fiber bridging, is proposed. Development of the composite failure diagram via micromechanical modeling of individual mechanisms is presented together with experimental results from the literature. Good correlation between theory and experiment suggests that the composite failure diagram might be used for tailoring composite properties through control of the dominant fracture mechanism.
Azar, R. Julian; Head-Gordon, Martin
2012-01-14
We propose a wave function-based method for the decomposition of intermolecular interaction energies into chemically-intuitive components, isolating both mean-field- and explicit correlation-level contributions. We begin by solving the locally-projected self-consistent field for molecular interactions equations for a molecular complex, obtaining an intramolecularly polarized reference of self-consistently optimized, absolutely-localized molecular orbitals (ALMOs), determined with the constraint that each fragment MO be composed only of atomic basis functions belonging to its own fragment. As explicit inter-electronic correlation is integral to an accurate description of weak forces underlying intermolecular interaction potentials, namely, coordinated fluctuations in weakly interacting electronic densities, we add dynamical correlation to the ALMO polarized reference at the coupled-cluster singles and doubles level, accounting for explicit dispersion and charge-transfer effects, which map naturally onto the cluster operator. We demonstrate the stability of energy components with basis set extension, follow the hydrogen bond-breaking coordinate in the C{sub s}-symmetry water dimer, decompose the interaction energies of dispersion-bound rare gas dimers and other van der Waals complexes, and examine charge transfer-dominated donor-acceptor interactions in borane adducts. We compare our results with high-level calculations and experiment when possible.
Suresh, S; Gunasekaran, S; Srinivasan, S
2015-03-01
The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100cm(-1) respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (?) and the first order hyper polarizability (?) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. PMID:25523048
Sherman, David M.
1990-01-01
Metal-metal charge-transfer and magnetic exchange interactions have important effects on the optical spectra, crystal chemistry, and physics of minerals. Previous molecular orbital calculations have provided insight on the nature of Fe2+-Fe3+ and Fe2+-Ti4+ charge-transfer transitions in oxides and silicates. In this work, spin-unrestricted molecular orbital calculations on (FeMnO10) clusters are used to study the nature of magnetic exchange and electron delocalization (charge transfer) associated with Fe3+-Mn2+, Fe3+-Mn3+, and Fe2+-Mn3+ interactions in oxides and silicates.
Molecular-orbital study of late-fission times in deep-inelastic 238U+238U collisions
NASA Astrophysics Data System (ADS)
Molitoris, J. D.; Meyerhof, W. E.; Stoller, Ch.; Anholt, R.; Spooner, D. W.; Moretto, L. G.; Sobotka, L. G.; McDonald, R. J.; Wozniak, G. J.; McMahan, M. A.; Blumenfeld, L.; Colonna, N.; Nessi, M.; Morenzoni, E.
1993-02-01
The U-like K-vacancy production probability in 7.5-MeV/nucleon deep-inelastic 238U+238U collisions has been measured for no-fission, single-fission, and double-fission exit channels. The results are interpreted using quasimolecular orbital correlations for diatomic and triatomic configurations. This leads to the determination of lower limits for the time scale for late fission of U-like products (>=8 and >=4 as) and their probability (>=77% and >=52%), at mean initial-excitation energies of ~40 and ~105 MeV, respectively.
NASA Astrophysics Data System (ADS)
Hofto, Laura; Hofto, Meghan; Cross, Jessica; Cafiero, Mauricio
2007-09-01
Many diseases can be traced to point mutations in the DNA coding for specific enzymes. These point mutations result in the change of one amino acid residue in the enzyme. We have developed a model using simple molecular orbital calculations which can be used to quantitatively determine the change in interaction between the enzyme's active site and necessary ligands upon mutation. We have applied this model to three hydroxylase proteins: phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase, and we have obtained excellent correlation between our results and observed disease symptoms. Furthermore, we are able to use this agreement as a baseline to screen other mutations which may also cause onset of disease symptoms. Our focus is on systems where the binding is due largely to dispersion, which is much more difficult to model inexpensively than pure electrostatic interactions. Our calculations are run in parallel on a sixteen processor cluster of 64-bit Athlon processors.
NASA Astrophysics Data System (ADS)
Abe, Jiro; Miyazaki, Tomo-o.; Takahashi, Hiroaki
1989-02-01
Ab initio STO-3G and semiempirical modified neglect of diatomic overlap (MNDO) calculations have been performed for the ground state, the radical cation, and the lowest triplet state of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD). The geometry of each state optimized by the ab initio calculation is not much different from that optimized by the MNDO calculation. The optimized structures of the ground state and the radical cation are both in good agreement with the structures determined by x-ray diffraction. It is concluded based on the molecular-orbital calculations as well as on our previously reported time-resolved resonance Raman spectra that the lowest triplet state of TMPD takes a ``softened'' 1,4-quinoid-like structure in the planar configuration with the C=C bonds of the phenyl ring being lengthened while the N-Ph bonds shortened.
NASA Astrophysics Data System (ADS)
Trout, Chad C.; Tambach, T. J.; Kubicki, James D.
2005-09-01
The aromatic carboxylic acids benzoic, salicylic and phthalic acid were used to study the interaction of soluble organics compounds with metal cations. To accomplish this, we have developed methods for studying the carboxylic acids using UV resonance Raman (UVRR) combined with molecular orbital density functional theory calculations. The pH values of the acid solutions were based on the p Ka's for the different acids to examine the neutral and charged species. Deprotonation of the organic acids was detectable down to 10 -4 M using UVRR (two orders of magnitude lower than previous vibrational spectroscopy studies). Limitations to decreasing the concentration lower using the current UVRR facilities are discussed. Two methods were used to calculate the optimized geometry and frequencies of the acids: explicit and continuum solvation. The frequencies from the experimental spectra were then compared to the theoretical results obtained from the two methods.
Trout, Chad C; Tambach, T J; Kubicki, James D
2005-09-01
The aromatic carboxylic acids benzoic, salicylic and phthalic acid were used to study the interaction of soluble organics compounds with metal cations. To accomplish this, we have developed methods for studying the carboxylic acids using UV resonance Raman (UVRR) combined with molecular orbital density functional theory calculations. The pH values of the acid solutions were based on the pK(a)'s for the different acids to examine the neutral and charged species. Deprotonation of the organic acids was detectable down to 10(-4)M using UVRR (two orders of magnitude lower than previous vibrational spectroscopy studies). Limitations to decreasing the concentration lower using the current UVRR facilities are discussed. Two methods were used to calculate the optimized geometry and frequencies of the acids: explicit and continuum solvation. The frequencies from the experimental spectra were then compared to the theoretical results obtained from the two methods. PMID:16043056
Jaume, J.C.; Portolano, S.; Prummel, M.F.; McLachlan, S.M.; Rapoport, B. [Univ. of California, San Francisco, CA (United States)] [Univ. of California, San Francisco, CA (United States)
1994-02-01
Graves` ophthalmopathy is a distressing autoimmune disease of unknown etiology. Analysis of the genes for antibodies secreted by orbital tissue-infiltrating plasma cells might provide insight into the pathogenesis of this disease. The authors, therefore, constructed an immunoglobulin heavy (H) chain and an immunoglobulin k light (L) chain cDNA library from the orbital tissue of a patient with active Graves` ophthalmopathy. Analysis of 15 H (IgG1) and 15 L (k) chains revealed a restricted spectrum of variable region genes. Fourteen of 15 variable k genes were about 94% homologous to the closest known germline gene, KL012. Thirteen of 15 H chain genes were 91% and 90% homologous to the closest germline genes, DP10 and hv1263, respectively. Remarkably, these germline genes also code for other autoantibodies to striated muscle (KL012) and thyroid peridase (KL012 and hv1263). These studies raise the possibility that particular germline genes may be associated with autoimmunity in humans. Further, the present study opens the way to identifying ocular autoantigens that may be the target of an humoral immune response. 29 refs., 4 figs., 1 tab.
NASA Astrophysics Data System (ADS)
Porchelvi, E. Elamurugu; Muthu, S.
2015-01-01
The thiosemicarbazone compound, Salicylaldehyde p-methylphenylthiosemicarbazone (abbreviated as SMPTSC) was synthesized and characterized by FTIR, FT-Raman and UV. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31++G(d,p) basis set. The molecular geometry and vibrational frequencies were calculated and compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The electronic dipole moment (?D) and the first hyperpolarizability (?tot) values of the investigated molecule were computed using density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set. The stability and charge delocalization of the molecule was studied by natural bond orbital (NBO) analysis. Thearomaticities of the phenyl rings were studied using the standard harmonic oscillator model of aromaticity (HOMA) index. Mulliken population analysis on atomic charges is also calculated. The molecule orbital contributions are studied by density of energy states (DOSs).
Sebastian, S; Sylvestre, S; Jayarajan, D; Amalanathan, M; Oudayakumar, K; Gnanapoongothai, T; Jayavarthanan, T
2013-01-15
In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the ?* and ?* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis. PMID:23123244
Papadopoulos, Anastasios G; Charistos, Nickolas D; Kyriakidou, Katerina; Sigalas, Michael P
2015-10-01
The electron delocalization in 1,2-azaborine, 1,3-azaborine, and 1,4-azaborine is studied using canonical molecular orbital contributions to the induced magnetic field (CMO-IMF) method and polyelectron population analysis (PEPA). Contour maps of the out-of-plane component of the induced magnetic field (Bz(ind)) of the ? system show that the three azaborines, in contrast with borazine, sustain much of benzene's ?-aromatic character. Among them, 1,3-azaborine exhibits the strongest ? delocalization, while 1,4-azaborine is the weakest. Contour maps of Bz(ind) for individual ? orbitals reveal that the differentiation of the magnetic response among the three isomers originates from the ?-HOMO orbitals, whose magnetic response is governed by rotational allowed transitions to unoccupied orbitals. The low symmetry of azaborines enables a paratropic response from HOMO to unoccupied orbitals excitations, with their magnitude depending on the shape of interacting orbitals. 1,3-Azaborine presents negligible paratropic contributions to Bz(ind) from HOMO to unoccupied orbitals transitions, where 1,2- and 1,4-azaborine present substantial paratropic contributions, which lead to reduced diatropic response. Natural bond orbital (NBO) analysis employing PEPA shows that only the 1,3-azaborine contains ?-electron fully delocalized resonance structures. PMID:26348255
NASA Technical Reports Server (NTRS)
1974-01-01
The orbiter mission of the Pioneer Venus probe is discussed. In accordance with the low-cost Pioneer Venus concept, NASA intends to use the same basic spacecraft, known as the bus, for the execution of the two missions. The bus will be equipped with all of the subsystems common to the probe and orbiter missions (for example, thermal control, solar cells and power supply, attitude measurement and control, telemetry and communication electronics, and auxiliary propulsion unit). For the 1977 mission, the bus will be equipped with the large and small probes and a special antenna system. For the orbiter mission, the bus will be equipped with a retro-propulsion motor and a high-gain antenna. A diagram of the system envisaged is shown.
Kobayashi, Masato
2014-02-28
The analytical gradient for the atomic-orbital-based Hartree–Fock–Bogoliubov (HFB) energy functional, the modified form of which was proposed by Staroverov and Scuseria to account for the static electron correlation [J. Chem. Phys. 117, 11107 (2002)], is derived. Interestingly, the Pulay force for the HFB energy is expressed with the same formula as that for the Hartree–Fock method. The efficiency of the present HFB energy gradient is demonstrated in the geometry optimizations of conjugated and biradical systems. The geometries optimized by using the HFB method with the appropriate factor ?, which controls the degree of static correlation included, are found to show good agreement with those obtained by using a complete active-space self-consistent field method, although they are significantly dependent on ?.
NASA Technical Reports Server (NTRS)
Patrick, E. L.; Earle, G. D.; Kasprzak, W. T.; Mahaffy, Paul R.
2008-01-01
From commercial origins as a molybdenum molecular beam nozzle, a ceramic nozzle of silicon carbide (SiC) was developed for space environment simulation. The nozzle is mechanically stable under extreme conditions of temperature and pressure. A heated, continuous, supersonically-expanded hydrogen beam with a 1% argon seed produced an argon beam component of nearly 4 km/s, with an argon flux exceeding 1x1014 /cm2.s. This nozzle was part of a molecular beam machine used in the Atmospheric Experiments Branch at NASA Goddard Space Flight Center to characterize the performance of the University of Texas at Dallas Ram Wind Sensor (RWS) aboard the Air Force Communications/Navigation Outage Forecasting System (C/NOFS) launched in the Spring of 2008.
NSDL National Science Digital Library
Dr. Charles Ward
This is a line drawing of a Windows PC keyboard complete with labels for each key. This diagram is used on tests where students are asked to circle the keys that would be used to perform various functions.
NASA Astrophysics Data System (ADS)
Aso, N.; Ohta, K.; Ide, S.
2014-12-01
Deformation in a small volume of earth interior is expressed by a symmetric moment tensor located on a point source. The tensor contains information of characteristic directions, source amplitude, and source types such as isotropic, double-couple, or compensated-linear-vector-dipole (CLVD). Although we often assume a double couple as the source type of an earthquake, significant non-double-couple component including isotropic component is often reported for induced earthquakes and volcanic earthquakes. For discussions on source types including double-couple and non-double-couple components, it is helpful to display them using some visual diagrams. Since the information of source type has two degrees of freedom, it can be displayed onto a two-dimensional flat plane. Although the diagram developed by Hudson et al. [1989] is popular, the trace corresponding to the mechanism combined by two mechanisms is not always a smooth line. To overcome this problem, Chapman and Leaney [2012] developed a new diagram. This diagram has an advantage that a straight line passing through the center corresponds to the mechanism obtained by a combination of an arbitrary mechanism and a double-couple [Tape and Tape, 2012], but this diagram has some difficulties in use. First, it is slightly difficult to produce the diagram because of its curved shape. Second, it is also difficult to read out the ratios among isotropic, double-couple, and CLVD components, which we want to obtain from the estimated moment tensors, because they do not appear directly on the horizontal or vertical axes. In the present study, we developed another new square diagram that overcomes the difficulties of previous diagrams. This diagram is an orthogonal system of isotropic and deviatoric axes, so it is easy to get the ratios among isotropic, double-couple, and CLVD components. Our diagram has another advantage that the probability density is obtained simply from the area within the diagram if the probability density function of moment tensor's eigenvalues P(?1, ?2, ?3) depends only on the scalar moment [(?12+?22+?32)/2]0.5. Even if this is not the real case, the easiness of calculating the areal density is useful when we compare the results of analyzing real data with that of analyzing background noise.
Thermodynamically Improbable Phase Diagrams
Hiroaki Okamoto; T. B Massalski
1991-01-01
Phase diagrams showing very unlikely boundaries, while not explicitly violating thermodynamic principles or phase rules, are\\u000a discussed. Phase rule violations in proposed phase diagrams often become apparent when phase boundaries are extrapolated into\\u000a metastable regions. In addition to phase rule violations, this article considers difficulties regarding an abrupt change of\\u000a slope of a phase boundary, asymmetric or unusually pointed liquidus
NSDL National Science Digital Library
This activity uses three experiments for students to construct a phase diagram; the experiments have been videotaped and can be seen online. The purpose of this laboratory as designed is to gain familiarity with simple phase diagrams, their construction, and their applications to the understanding of geological and environmental problems. Subsidiary objectives include development of strategies for data processing including evaluation of assumptions and sources of errors, as well as honing of computer, spreadsheet, presentation (tabular and graphical), and report writing skills.
NASA Astrophysics Data System (ADS)
Kishi, Ryohei; Fujii, Hiroaki; Minami, Takuya; Shigeta, Yasuteru; Nakano, Masayoshi
2015-01-01
In this study, we apply the ab initio molecular orbital - configuration interaction based quantum master equation (MOQME) approach to the calculation and analysis of the dynamic first hyperpolarizabilities (?) of asymmetric ?-conjugated molecules. In this approach, we construct the excited state models by the ab initio configuration interaction singles method. Then, time evolutions of system reduced density matrix ?(t) and system polarization p(t) are calculated by the QME approach. Dynamic ? in the second harmonic generation is calculated based on the nonperturbative definition of nonlinear optical susceptibility, using the frequency domain system polarization p(?). Spatial contributions of electrons to ? are analyzed based on the dynamic hyperpolarizability density map, which visualizes the second-order response of charge density oscillating with a frequency of 2?. We apply the present method to the calculation of the dynamic ? of a series of donor/acceptor substituted polyene oligomers, and then discuss the applicability of the MOQME method to the calculation and analysis of dynamic NLO properties of molecular systems.
NASA Astrophysics Data System (ADS)
Zoba?, Vladimír; Lewis, James P.; Abad, Enrique; Mendieta-Moreno, Jesús I.; Hapala, Prokop; Jelínek, Pavel; Ortega, José
2015-05-01
The computational simulation of photo-induced processes in large molecular systems is a very challenging problem. Firstly, to properly simulate photo-induced reactions the potential energy surfaces corresponding to excited states must be appropriately accessed; secondly, understanding the mechanisms of these processes requires the exploration of complex configurational spaces and the localization of conical intersections; finally, photo-induced reactions are probability events, that require the simulation of hundreds of trajectories to obtain the statistical information for the analysis of the reaction profiles. Here, we present a detailed description of our implementation of a molecular dynamics with electronic transitions algorithm within the local-orbital density functional theory code FIREBALL, suitable for the computational study of these problems. As an example of the application of this approach, we also report results on the [2 + 2] cycloaddition of ethylene with maleic anhydride and on the [2 + 2] photo-induced polymerization reaction of two C60 molecules. We identify different deactivation channels of the initial electron excitation, depending on the time of the electronic transition from LUMO to HOMO, and the character of the HOMO after the transition.
Zoba?, Vladimír; Lewis, James P; Abad, Enrique; Mendieta-Moreno, Jesús I; Hapala, Prokop; Jelínek, Pavel; Ortega, José
2015-05-01
The computational simulation of photo-induced processes in large molecular systems is a very challenging problem. Firstly, to properly simulate photo-induced reactions the potential energy surfaces corresponding to excited states must be appropriately accessed; secondly, understanding the mechanisms of these processes requires the exploration of complex configurational spaces and the localization of conical intersections; finally, photo-induced reactions are probability events, that require the simulation of hundreds of trajectories to obtain the statistical information for the analysis of the reaction profiles. Here, we present a detailed description of our implementation of a molecular dynamics with electronic transitions algorithm within the local-orbital density functional theory code FIREBALL, suitable for the computational study of these problems. As an example of the application of this approach, we also report results on the [2 + 2] cycloaddition of ethylene with maleic anhydride and on the [2 + 2] photo-induced polymerization reaction of two C60 molecules. We identify different deactivation channels of the initial electron excitation, depending on the time of the electronic transition from LUMO to HOMO, and the character of the HOMO after the transition. PMID:25791682
Saravanan, S; Balachandran, V; Vishwanathan, K
2014-04-24
The FT-IR and FT-Raman spectra of 4-tert-butyl-3-methoxy-2,6-dinitrotoluene (musk ambrette) have been recorded in the regions 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The total energy calculations of musk ambrette were tried for the possible conformers. The molecular structure, geometry optimization, vibrational frequencies were obtained by the density functional theory (DFT) using B3LYP and LSDA method with 6-311G(d,p) basis set for the most stable conformer "C1". The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated and the scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The stability of the molecule arising from hyper conjugate interactions and the charge delocalization has been analyzed using bond orbital (NBO) analysis. The HOMO and LUMO energy gap reveals that the energy gap reflects the chemical activity of the molecule. The dipole moment (?), polarizability (?), anisotropy polarizability (??) and first hyperpolarizability (?tot) of the molecule have been reported. The thermodynamic functions (heat capacity, entropy and enthalpy) were obtained for the range of temperature 100-1000 K. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP). PMID:24508884
Che, Yanke; Gross, Dustin E; Huang, Helin; Yang, Dongjiang; Yang, Xiaomei; Discekici, Emre; Xue, Zheng; Zhao, Huijun; Moore, Jeffrey S; Zang, Ling
2012-03-14
Development of simple, cost-effective, and sensitive fluorescence-based sensors for explosives implies broad applications in homeland security, military operations, and environmental and industrial safety control. However, the reported fluorescence sensory materials (e.g., polymers) usually respond to a class of analytes (e.g., nitroaromatics), rather than a single specific target. Hence, the selective detection of trace amounts of trinitrotoluene (TNT) still remains a big challenge for fluorescence-based sensors. Here we report the selective detection of TNT vapor using the nanoporous fibers fabricated by self-assembly of carbazole-based macrocyclic molecules. The nanoporosity allows for time-dependent diffusion of TNT molecules inside the material, resulting in further fluorescence quenching of the material after removal from the TNT vapor source. Under the same testing conditions, other common nitroaromatic explosives and oxidizing reagents did not demonstrate this postexposure fluorescence quenching; rather, a recovery of fluorescence was observed. The postexposure fluorescence quenching as well as the sensitivity is further enhanced by lowering the highest occupied molecular orbital (HOMO) level of the nanofiber building blocks. This in turn reduces the affinity for oxygen, thus allocating more interaction sites for TNT. Our results present a simple and novel way to achieve detection selectivity for TNT by creating nanoporosity and tuning molecular electronic structure, which when combined may be applied to other fluorescence sensor materials for selective detection of vapor analytes. PMID:22339204
NASA Technical Reports Server (NTRS)
Hurlbert, Eric A.
2001-01-01
This slide presentation reviews the Space Shuttle's On-Orbit Propulsion systems: the Orbital Maneuvering System (OMS) and the Reaction Control System (RCS). The functions of each of the systems is described, and the diagrams of the systems are presented. The OMS/RCS thruster is detailed and a trade study comparison of non-toxic propellants is presented.
George D. Markham; Cindy L. Bock; Mendel Trachtman; Charles W. Bock
1999-01-01
Ab initio molecular orbital and density functional methods have been used to study the potential energy surfaces of the substituted acetic acids HX—CH2—COOH, where X is one of the Group VIA Chalcophiles S, Se, or Te. The various conformers adopted by these compounds provide information regarding the energetic importance of nonbonded \\u000a
... called the orbit. The orbit is the hollow space in the skull where the eye sits. The orbit protects the eyeball and the muscles and tissue that surround it. Orbital pseudotumor does not spread to other tissues or places in the body.
Stellar orbits in angle variables
NASA Astrophysics Data System (ADS)
Ratcliff, S. J.; Chang, K. M.; Schwarzschild, M.
1984-04-01
Following recent basic developments by Binney and Spergel, the equations of motion for a star in a galactic potential have been transformed from time to angle variables. A numerical procedure has been devised to solve the transformed equations for two-dimensional box and loop orbits in the equatorial plane of a triaxial potential. In this procedure an orbit is specified not by its starting values in phase space, but either by its frequencies or by its action values. A substantial set of orbits has been derived by this procedure for one potential. The results for their physical and geometrical characteristics are displayed in action diagrams.
NASA Astrophysics Data System (ADS)
Lumbroso, H.; Liégeois, C.; Pappalardo, G. C.; Grassi, A.
From the ab initio molecular energies of the possible conformers and from a classical dipole moment analysis of 2-oxopyrrolidin-l-ylacetamide (? = 4.02 D in dioxan at 30.0°C), the preferred conformation in solution of this novel nootropic agent has been determined. The exocyclic N-CH 2 bond is rotated in one sense by 90° and the exocyclic CH 2-C bond rotated in the same sense by 120° from the "planar" ( OO)- cis conformation. The structures of the two enantiomers in solution differ from that of the crystalline molecule.
The distorted kinematics of molecular gas in the center of NGC 891.
NASA Astrophysics Data System (ADS)
Garcia-Burillo, S.; Guelin, M.
1995-07-01
The center of the edge-on spiral galaxy NGC 891 has been mapped in the J=2-1 and J=1-0 transitions of ^12^CO using the IRAM 30m telescope, with spatial resolutions of 13" and 21" respectively. The kinematics of molecular gas in the inner regions of the galaxy is particularly distorted. The position-velocity diagram (p-v) taken along the kinematical major axis of NGC 891 is strikingly similar to the Galaxy's longitude-velocity plot (l-v). As in our Galaxy, we have detected in NGC 891 molecular gas circulating at velocities "forbidden" by a law based only on circular rotation. Following the work of Binney et al. (1991) on the interpretation of our Galaxy's CO l-v diagram, we have developed a model on the gas kinematics of the inner regions of NGC 891 that explains satisfactorily the major features of the CO p-v diagram. In our model, the flow of molecular gas is driven by a bar that has corotation at r~3kpc and that is viewed at an angle ?~ 45deg from its major axis. Molecular clouds circulate along x_2_ orbits (elliptical orbits perpendicular to the bar) between the two Inner Linblad Resonances (ILR), and partly populate x_1_ orbits (ellipses parallel to the bar) in the outer regions (from the outer ILR up to the corotation circle). We can also explain the radial distribution of molecular gas: the great ring of molecular material at r~4.5-6kpc might be associated with the Outer Linblad Resonance of the bar (OLR) and the adjacent hole of molecular gas inside this radius, with the corotation circle. The observed kinematics of molecular gas in the center of the edge-on spiral NGC 5907, as well as a number of other galaxies, could be also interpreted in terms of highly elliptical orbits driven by bars or triaxial potentials.
Space Shuttle Orbiter auxiliary power unit status
NASA Astrophysics Data System (ADS)
Reck, M.; Loken, G.; Horton, J.; Lukens, W.; Scott, W.; Baughman, J.; Bauch, T.
An overview of the United States Space Shuttle Orbiter APU, which provides power to the Orbiter vehicle hydraulic system, is presented. Three complete APU systems, each with its own separate fuel system, supply power to three dedicated hydraulic systems. These in turn provide power to all Orbiter vehicle critical flight functions including launch, orbit, reentry, and landing. The basic APU logic diagram is presented. The APU includes a hydrazine-powered turbine that drives a hydraulic pump and various accessories through a high-speed gearbox. The APU also features a sophisticated thermal management system designed to ensure safe and reliable operation in the various launch, orbit, reentry, and landing environments.
Space Shuttle Orbiter auxiliary power unit status
NASA Technical Reports Server (NTRS)
Reck, M.; Loken, G.; Horton, J.; Lukens, W.; Scott, W.; Baughman, J.; Bauch, T.
1991-01-01
An overview of the United States Space Shuttle Orbiter APU, which provides power to the Orbiter vehicle hydraulic system, is presented. Three complete APU systems, each with its own separate fuel system, supply power to three dedicated hydraulic systems. These in turn provide power to all Orbiter vehicle critical flight functions including launch, orbit, reentry, and landing. The basic APU logic diagram is presented. The APU includes a hydrazine-powered turbine that drives a hydraulic pump and various accessories through a high-speed gearbox. The APU also features a sophisticated thermal management system designed to ensure safe and reliable operation in the various launch, orbit, reentry, and landing environments.
González-Rodríguez, David; Carbonell, Esther; Rojas, Gustavo de Miguel; Castellanos, Carmen Atienza; Guldi, Dirk M; Torres, Tomás
2010-11-24
We have synthesized two different fullerene-subphthalocyanine-ferrocene conjugates. The molecules were designed so that the ferrocene unit is linked at the subphthalocyanine axial position through a phenoxy spacer while the C(60) is rigidly held close to the concave face of the macrocycle via a 3-fold C(3)-symmetrical anchoring. The Bingel trisaddition reaction leading to the final products proceeded with very high regioselectivities and full diastereoselectivity. The only difference between both systems is the length of the triple tether employed, which finely regulates the regioselectivity of the trisaddition reaction and the distance between the subphthalocyanine and the C(60) complementary ?-? surfaces. Thus, when the tether is connected to the subphthalocyanine through a direct C-C bond, a short ?-? distance of 3.25-3.30 Å was calculated. In contrast, when it is connected through a slightly longer C-O-C bond, the distance increases to 3.5-3.6 Å. This ?-? distance has a strong influence on the ground-state electronic interactions between the subphthalocyanine and the C(60), as determined from electronic absorption and cyclic voltammetry measurements. In addition, fluorescence and time-resolved transient absorption experiments demonstrated that different mechanisms operate in the two systems after photoexcitation. Despite the similar HOMO-LUMO gaps, only when the two complementary ?-? surfaces of the subphthalocyanine and the C(60) are held at a close distance, therefore showing a high degree of orbital overlap, is a multistep electron transfer process triggered, ultimately leading to the long-lived, spatially separated C(60) radical anion and ferrocenium radical cation pair. A full account of the synthesis, characterization, and studies of the ground- and excited-state electronic interactions occurring in these conjugates, as well as in their reference C(60)-subphthalocyanine and subphthalocyanine-ferrocene dyads, is presented in this article. PMID:21033683
Sciortino, Francesco
Accurate phase diagram of tetravalent DNA nanostars Lorenzo Rovigatti, Francesca Bomboi, 174503 (2013); 10.1063/1.4802777 Phase diagram of colloid-rod system J. Chem. Phys. 132, 044905 (2010); 10.1063/1.3298993 Phase diagrams of alkali halides using two interaction models: A molecular dynamics
NASA Technical Reports Server (NTRS)
Bergeron, R. P.
1980-01-01
Orbital transfer vehicle propulsion options for SPS include both chemical (COTV) and electrical (EOTV) options. The proposed EOTV construction method is similar to that of the SPS and, by the addition of a transmitting antenna, may serve as a demonstration or precursor satellite option. The results of the studies led to the selection of a single stage COTV for crew and priority cargo transfer. An EOTV concept is favored for cargo transfer because of the more favorable orbital burden factor over chemical systems. The gallium arsenide solar array is favored over the silicon array because of its self annealing characteristics of radiation damage encountered during multiple transitions through the Van Allen radiation belt. Transportation system operations are depicted. A heavy lift launch vehicle (HLLV) delivers cargo and propellants to LEO, which are transferred to a dedicated EOTV by means of an intraorbit transfer vehicle (IOTV) for subsequent transfer to GEO. The space shuttle is used for crew transfer from Earth to LEO. At the LEO base, the crew module is removed from the shuttle cargo bay and mated to a COTV for transfer to GEO. Upon arrival at GEO, the SPS construction cargo is transferred from the EOTV to the SPS construction base by IOTV. Crew consumables and resupply propellants are transported to GEO by the EOTV. Transportation requirements are dominated by the vast quantity of materials to be transported to LEO and GEO.
NASA Astrophysics Data System (ADS)
Koch, Wolfhard; Freyb, Bastian; Ruiza, Juan Francisco Sánchez; Scior, Thomas
2003-12-01
Rüdenberg's well-known letter of 1951 entitled "On the Three- and Four-Center Integrals in Molecular Quantum Mechanics" explicitly presents two approximation formulas for four-center repulsion integrals, only. When applied to some types of three-center repulsion integrals, however, these two recipes still imply considerable oversimplifications. Using both one-electron and two-electron routes of Rüdenberg's truncated expansion, on the other hand, such shortcomings can be avoided strictly. Starting from four simple "Unrestricted and Combined" (U&C) approximation schemes introduced elsewhere, an improved "Restricted and Combined" (R&C) approximation picture for Fock-matrix elements now will be outlined, which does not tolerate any unnecessary oversimplifications. Although the simplicity of the U&C scheme is lost in this case, R&C-approximated Fock-matrix elements still can be constructed from one- and two-center integrals alone in an effective way. Moreover, due to their dependence on a single geometric parameter, all types of two-center integrals can be calculated in advance for about one hundred fixed interatomic distances at the desired level of sophistication and stored once and for all. A cubic spline algorithm may be taken to interpolate the actual integral value from each precomputed list.
NASA Astrophysics Data System (ADS)
Belal, Arafa A. M.; Zayed, M. A.; El-Desawy, M.; Rakha, Sh. M. A. H.
2015-03-01
Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and 1H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ?E?, ?H?, ?S? and ?G? were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.
NASA Astrophysics Data System (ADS)
Suresh, S.; Gunasekaran, S.; Srinivasan, S.
2014-11-01
The solid phase FT-IR and FT-Raman spectra of 2-hydroxybenzoic acid (salicylic acid) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method at 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimentally obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method is employed to predict its absorption energy and oscillator strength. The linear polarizability (?) and the first order hyper polarizability (?) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MEP) are also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.
NASA Astrophysics Data System (ADS)
Govindasamy, P.; Gunasekaran, S.
2015-02-01
The molecular structural parameters and vibrational frequencies of the fundamental modes of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide(abbreviated as 4MPTFM1HPB1SA) have been obtained using Density functional theory (DFT) technique in the B3LYP approximation with 6-311G(d,p) and 6-311++G(d,p) basis sets. Detailed vibrational assignments of the observed FT-IR and FT-Raman bands have been proposed on the basis of potential energy distribution (PED). The difference between the observed and the calculated wavenumbers values are very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities toward electrophilic and nucleophilic attack. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. Important non-linear properties such as electric dipolemoment and first hyperpolarizability of 4MPTFM1HPB1SA have been computed using B3LYP quantum chemical calculation. The absorption wavelength, energy and oscillator's strength are calculated by TD-DFT and 4MPTFM1HPB1SA is approach complement with the experimental findings. The temperature dependence of thermodynamic properties has been analyzed. The Natural charges, Frontier molecular orbitals (FMOs), chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported.
NSDL National Science Digital Library
Dexter Perkins
This is a short exercise aimed at evaluating whether students understand how to interpret the Ab-An phase diagram. If students know what is going on, it takes about 10 minutes to complete. This active learning exercise makes a good break from lecture. It is best done as a group activity.
ERIC Educational Resources Information Center
Rosengrant, David
2011-01-01
Multiple representations are a valuable tool to help students learn and understand physics concepts. Furthermore, representations help students learn how to think and act like real scientists. These representations include: pictures, free-body diagrams, energy bar charts, electrical circuits, and, more recently, computer simulations and…
NSDL National Science Digital Library
Michael Horton
2009-05-30
This inquiry activity will be students' first exposure to ray diagrams. They will be using the refraction of sound to simulate the refraction of light to introduce them to this concept. They will be creating a simulated convex lens with a CO 2 -f
NASA Astrophysics Data System (ADS)
Kreimer, Dirk
2000-07-01
1. Introduction; 2. Perturbative quantum field theory; 3. The Hopf algebra structure of renormalization; 4. Rationality: no knots, no transcendentals; 5. The simplest link diagrams; 6. Necessary topics from knot theory; 7. Knots to numbers; 8. One-loop words; 9. Euler-Zagier sums; 10. Knots and transcendentals; 11. The 4-term relation; 12. Hopf algebras, non-commutative geometry, and what else?
NASA Astrophysics Data System (ADS)
Sato, Kota; Shinagawa, Eiji; Nakajima, Kenji; Miyazaki, Kaori; Koinuma, Hideomi
2003-12-01
Hydrogen plasma treatment of a highly oriented pyrolytic graphite (HOPG) surface induces a marked change in the growth of a-Si:H film by glow-discharged decomposition of SiH4. Scanning tunneling microscope (STM) observation verified that the inhomogeneous islandlike growth on as-cleaved HOPG became homogenous after the surface was treated with hydrogen plasma. This drastic change in the surface chemical process could be reasonably interpreted by the ab initio molecular orbital calculations performed on the following reaction models: (1) C24H12 + H ? HC24H12 and (2) HC24H12 + SiH3 ? HC24H12SiH3. A stable energy minimum was obtained for H addition. H addition to the HOPG surface causes radical formation on the neighboring sp2 carbons, which were in turn spontaneously attacked by SiH3 radicals in the plasma to initiate homogeneous a-Si:H film growth. Without hydrogen plasma treatment, SiH3 radicals would attack the highly conjugated sp2 carbon surface. Therefore, a-Si:H film growth is presumed to be initiated at sparsely distributed defect sites that induce island growth.
NASA Astrophysics Data System (ADS)
Voigt, A.; Abram, U.; Böttcher, R.; Richter, U.; Reinhold, J.; Kirmse, R.
2000-03-01
A Q-band single-crystal EPR study of tetraphenylarsoniumtetrachloro-nitridorhenate(VI), [(C 6H 5) 4As][Re VINCl 4], diamagnetically diluted by the isoelectronic oxorhenate(V) complex is reported. The EPR spectra are typical of an ion with 5d 1 ( S=1/2) configuration and are influenced by large rhenium hyperfine coupling constants and nuclear quadrupole interactions. They are characterized by well-resolved 185,187Re hyperfine patterns with almost equal spacings and the occurrence of "forbidden" transitions ( ?mI=±1, ?mI=±2). The 185,187Re hyperfine parameters as well as the data obtained from density functional theory (DFT) and the extended Hückel theory (EHT) molecular orbital calculations are used to analyze the spin density distribution in the system under study. Thereby, the negative sign found for the spin density at the nitrogen from DFT is mainly determined by spin polarization. In addition, both MO methods are used to calculate the electric field gradient being responsible for the 185,187Re nuclear quadrupole coupling.
NASA Astrophysics Data System (ADS)
Zhang, Zhaofu; Geng, Zhaohui; Cai, Danyun; Pan, Tongxi; Chen, Yixin; Dong, Liyuan; Zhou, Tiege
2015-01-01
A first-principles calculation based on density functional theory is carried out to reveal the geometry, electronic structures and magnetic properties of hexagonal boron nitride sheets (h-BNSs) doped by 5d transitional mental atoms (Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au and Hg) at boron-site (B5d) and nitrogen-site (N5d). Results of pure h-BNS, h-BNS with B vacancy (VB) and N vacancy (VN) are also given for comparison. It is shown that all the h-BNSs doped with 5d atoms possess a C3v local symmetry except for NLu and NHg which have a clear deviation. For the same 5d dopant, the binding energy of B5d is larger than that of N5d, which indicates the substitution of a 5d atom for B is preferred. The total densities of states are presented, where impurity energy levels exist. Besides, the total magnetic moments (TMMs) change regularly with the increment of the 5d atomic number. Theoretical analyses by molecular orbital under C3v symmetry explain the impurity energy levels and TMMs.
Ab initio molecular orbital study of Fe{sub 2}C1{sub 6} and FeA1C1{sub 6}.
Scholz, G.; Curtiss, L. A.; Humboldt Univ. zu Berlin
2000-07-24
Ab initio molecular orbital theory was used to determine the equilibrium structure and vibrational frequencies of Fe{sub 2}Cl{sub 6} and FeAlCl{sub 6}. The equilibrium structure the Fe{sub 2}Cl{sub 6} dimer has D{sub 2h} symmetry with a planar arrangement of the four membered {l_brace}FeCl{sub br}FeCl{sub br}{r_brace} ring, similar to the Al{sub 2}Cl{sub 6} dimer. The calculated bond distances and vibrational frequencies are in good agreement with experiment. The potential energy surface for the puckering of the {l_brace}FeCl{sub br}FeCl{sub br}{r_brace} ring is extremely flat. This prevents an unambiguous assignment of either D{sub 2h} or C{sub 2v} symmetry to the Fe{sub 2}Cl{sub 6}structure in electron diffraction measurements. The FeAlCl{sub 6} molecule is found to have a C{sub 2v} structure similar to Fe{sub 2}Cl{sub 6} with vibrational frequencies in good agreement with experiment.
Phase diagram of the polymeric nitrogen
NASA Astrophysics Data System (ADS)
Yakub, L. N.
2015-06-01
The results of theoretical prediction of the phase transition lines of molecular nitrogen into the polymeric phase at high pressure are presented. The role of the polymeric phase structure in the location of the transition lines on the phase diagram is considered. Possible configuration of the melting curve of the polymeric nitrogen solid forming the polymeric liquid is discussed. Predicted volumes of the coexisting phases are compared with experimental data and with results of the computer simulations.
Orbital maneuvers between halo orbits
NASA Astrophysics Data System (ADS)
Prado, A.; Felipe, G.
This paper has the goal of studying the problem of orbital transfers between two Halo orbits Halo orbits are special three-dimensional trajectories that exist around the Lagrangian points of the restricted three-body problem These orbits are studied in several papers since they have important applications in astronautics The first step involved in this research is to perform the determination of the Halo orbits To do that an analytic calculation is performed using the Linstedt-Poincar e method The present paper considers that a maneuver will be performed to transfer the spacecraft from an initial to a final Halo orbit The control that will be used to achieve that goal is constituted by a pair of instantaneous change in the velocity of the spacecraft at the beginning and at the end of the maneuver A numerical algorithm based in the Lambert Problem is built to calculate the transfer orbits The two orbits are divided in several points and the algorithm is applied to each pair of points Finally the solution that gives the minimum fuel consumption is found This maneuver can be used to i change the orbit of the spacecraft to allow a second application in a different Halo orbit ii to perform station keeping in a Halo orbit that is escaping from its nominal orbital parameters
Orbitally induced string formation in the spin-orbital polarons
NASA Astrophysics Data System (ADS)
Wohlfeld, Krzysztof; Ole?, Andrzej M.; Horsch, Peter
2009-06-01
We study the spectral function of a single hole doped into the ab plane of the Mott insulator LaVO3 , with antiferromagnetic (AF) spin order of S=1 spins accompanied by alternating orbital (AO) order of active {dyz,dzx} orbitals. Starting from the respective t-J model, with spin-orbital superexchange and effective three-site hopping terms, we derive the polaron Hamiltonian and show that a hole couples simultaneously to the collective excitations of the AF/AO phase, magnons, and orbitons. Next, we solve this polaron problem using the self-consistent Born approximation and find a stable quasiparticle solution—a spin-orbital polaron. We show that the spin-orbital polaron resembles the orbital polaron found in eg systems, as e.g., in K2CuF4 or (to some extent) in LaMnO3 , and that the hole may be seen as confined in a stringlike potential. However, the spins also play a crucial role in the formation of this polaron—we explain how the orbital degrees of freedom: (i) confine the spin dynamics acting on the hole as the classical Ising spins and (ii) generate the string potential which is of the joint spin-orbital character. Finally, we discuss the impact of the results presented here on the understanding of the phase diagrams of the lightly doped cubic vanadates.
Dominic J. D. Hughes
2008-05-11
Linking diagrams with path composition are ubiquitous, for example: Temperley-Lieb and Brauer monoids, Kelly-Laplaza graphs for compact closed categories, and Girard's multiplicative proof nets. We construct the category Link=Span(iRel), where iRel is the category of injective relations (reversed partial functions) and show that the aforementioned linkings, as well as Jones-Martin partition monoids, reside inside Link. Path composition, including collection of loops, is by pullback. Link contains the free compact closed category on a self-dual object (hence also the looped Brauer and Temperly-Lieb monoids), and generalises partition monoids with partiality (vertices in no partition) and empty- and infinite partitions. Thus we obtain conventional linking/partition diagrams and their composition "for free", from iRel.
Iftikhar Ahmad; Yun-Song Piao; Cong-Feng Qiao
2009-03-28
Recently, it was showed that there is a large N phase transition in Nflation, in which when the number of fields is large enough, the slow roll inflation phase will disappear. In this brief report, we illustrate the phase diagram for Nflation, and discuss the entropy bound and some relevant results. It is found that near the critical point the number of fields saturates dS entropy.
Wilms, R Scott; Carlson, Bryan; Coons, James; Kubic, William
2008-01-01
This presentation describes the development of the proposed Process Flow Diagram (PFD) for the Tokamak Exhaust Processing System (TEP) of ITER. A brief review of design efforts leading up to the PFD is followed by a description of the hydrogen-like, air-like, and waterlike processes. Two new design values are described; the mostcommon and most-demanding design values. The proposed PFD is shown to meet specifications under the most-common and mostdemanding design values.
On web diagrams Jun Murakami Department of Mathematics, Graduate School of Science, Osaka tive invariant is defined in the space of web diagrams, and it includes the Casson Walker invariant of the mapping class groups. (cf. [9], [10]) 2. Web space 2.1. Web diagram. To explain the universal perturbative
Quantum phases of atomic Fermi gases with anisotropic spin-orbit coupling
Iskin, M. [Department of Physics, Koc University, Rumelifeneri Yolu, 34450 Saryer, Istanbul (Turkey); Subasi, A. L. [Department of Physics, Faculty of Science and Letters, Istanbul Technical University, 34469 Maslak, Istanbul (Turkey)
2011-10-15
We consider a general anisotropic spin-orbit coupling and analyze the phase diagrams of both balanced and imbalanced Fermi gases for the entire BCS-BEC evolution. In the first part, we use the self-consistent mean-field theory at zero temperature, and show that the topological structure of the ground-state phase diagrams is quite robust against the effects of anisotropy. In the second part, we go beyond the mean-field description, and investigate the effects of Gaussian fluctuations near the critical temperature. This allows us to derive the time-dependent Ginzburg-Landau theory, from which we extract the effective mass of the Cooper pairs and their critical condensation temperature in the molecular BEC limit.
Orbital Dzyaloshinskii-Moriya Exchange Interaction
NASA Astrophysics Data System (ADS)
Kim, Panjin; Han, Jung Hoon
2014-03-01
A superexchange calculation is performed for multi-orbital band models with broken inversion symmetry. Orbital-changing hopping terms allowed by the symmetry breaking electric field lead to a new kind of orbital exchange interaction closely resembling the Dzyaloshinskii-Moriya spin exchange. Inversion symmetry breaking as present in surfaces and interfaces and a strong on-site repulsion, but not the spin-orbit interaction, are the requirements to observe the proposed effect. Mean-field phase diagram exhibits a rich structure including anti-ferro-orbital, ferro-orbital, and both single and multiple spiral-orbital phases in close analogy with the Skyrmion spin crystal phase recently discovered in thin-film chiral magnets. J.H.H. is supported by NRF Grant No. 2011-0015631. P.K. is supported by a NRF grant funded by the Korean government (NRF-2012)-Global Ph.D. Fellowship Program.
Csaki, Csaba; Grossman, Yuval; Tanedo, Philip; Tsai, Yuhsin
2011-04-01
We present an analysis of the loop-induced magnetic dipole operator in the Randall-Sundrum model of a warped extra dimension with anarchic bulk fermions and an IR brane-localized Higgs. These operators are finite at one-loop order and we explicitly calculate the branching ratio for {mu}{yields}e{gamma} using the mixed position/momentum space formalism. The particular bound on the anarchic Yukawa and Kaluza-Klein (KK) scales can depend on the flavor structure of the anarchic matrices. It is possible for a generic model to either be ruled out or unaffected by these bounds without any fine-tuning. We quantify how these models realize this surprising behavior. We also review tree-level lepton flavor bounds in these models and show that these are on the verge of tension with the {mu}{yields}e{gamma} bounds from typical models with a 3 TeV Kaluza-Klein scale. Further, we illuminate the nature of the one-loop finiteness of these diagrams and show how to accurately determine the degree of divergence of a five-dimensional loop diagram using both the five-dimensional and KK formalism. This power counting can be obfuscated in the four-dimensional Kaluza-Klein formalism and we explicitly point out subtleties that ensure that the two formalisms agree. Finally, we remark on the existence of a perturbative regime in which these one-loop results give the dominant contribution.
Impact decision support diagrams
NASA Astrophysics Data System (ADS)
Boslough, Mark
2014-10-01
One way to frame the job of planetary defense is to “find the optimal approach for finding the optimal approach” to NEO mitigation. This requires a framework for defining in advance what should be done under various circumstances. The two-dimensional action matrix from the recent NRC report “Defending Planet Earth” can be generalized to a notional “Impact Decision Support Diagram” by extending it into a third dimension. The NRC action matrix incorporated two important axes: size and time-to-impact, but probability of impact is also critical (it is part of the definitions of both the Torino and Palermo scales). Uncertainty has been neglected, but is also crucial. It can be incorporated by subsuming it into the NEO size axis by redefining size to be three standard deviations greater than the best estimate, thereby providing a built-in conservative margin. The independent variable is time-to-impact, which is known with high precision. The other two axes are both quantitative assessments of uncertainty and are both time dependent. Thus, the diagram is entirely an expression of uncertainty. The true impact probability is either one or zero, and the true size does not change. The domain contains information about the current uncertainty, which changes with time (as opposed to reality, which does not change).
Orbiting in inelastic scattering
NASA Astrophysics Data System (ADS)
Sisak, Michael; Secrest, Don
1991-04-01
An investigation is made of several manifestations of the orbiting of two scattering partners. One focus is the effect on the l-average coupled states approximation and its first-order perturbational improvement, the l-average recoupled states approximation. Both methods are shown to fail completely when applied to m-dependent and degeneracy averaged differential and integral cross sections for inelastic collisions of an atom and a rigid rotor when there is significant orbiting behavior. A series of calculations is made for the He-SiO system scattering at 2.25, 9.01, 18.0, and 27.0 meV. The gradual improvement of both approximations with energy is clearly demonstrated. Additionally, close coupling differential and integral cross sections are shown to be extremely sensitive to slight energy changes in the orbiting regime. Moreover, single energy results in this regime are shown to differ significantly from results averaged over a molecular beam's energy distribution.
Orbiter Autoland reliability analysis
NASA Technical Reports Server (NTRS)
Welch, D. Phillip
1993-01-01
The Space Shuttle Orbiter is the only space reentry vehicle in which the crew is seated upright. This position presents some physiological effects requiring countermeasures to prevent a crewmember from becoming incapacitated. This also introduces a potential need for automated vehicle landing capability. Autoland is a primary procedure that was identified as a requirement for landing following and extended duration orbiter mission. This report documents the results of the reliability analysis performed on the hardware required for an automated landing. A reliability block diagram was used to evaluate system reliability. The analysis considers the manual and automated landing modes currently available on the Orbiter. (Autoland is presently a backup system only.) Results of this study indicate a +/- 36 percent probability of successfully extending a nominal mission to 30 days. Enough variations were evaluated to verify that the reliability could be altered with missions planning and procedures. If the crew is modeled as being fully capable after 30 days, the probability of a successful manual landing is comparable to that of Autoland because much of the hardware is used for both manual and automated landing modes. The analysis indicates that the reliability for the manual mode is limited by the hardware and depends greatly on crew capability. Crew capability for a successful landing after 30 days has not been determined yet.
Program Synthesizes UML Sequence Diagrams
NASA Technical Reports Server (NTRS)
Barry, Matthew R.; Osborne, Richard N.
2006-01-01
A computer program called "Rational Sequence" generates Universal Modeling Language (UML) sequence diagrams of a target Java program running on a Java virtual machine (JVM). Rational Sequence thereby performs a reverse engineering function that aids in the design documentation of the target Java program. Whereas previously, the construction of sequence diagrams was a tedious manual process, Rational Sequence generates UML sequence diagrams automatically from the running Java code.
Generating function for web diagrams
A. A. Vladimirov
2014-09-06
We present the description of the exponentiated diagrams in terms of generating function within the universal diagrammatic technique. In particular, we show the exponentiation of the gauge theory amplitudes involving products of an arbitrary number of Wilson lines of arbitrary shapes, which generalizes the concept of web diagrams. The presented method gives a new viewpoint on the web diagrams and proves the non-Abelian exponentiation theorem.
Shuttle Compatible Orbit Transfer Subsystem (SCOTS)
NASA Astrophysics Data System (ADS)
Balzer, D. L.; Larsen, C. R.
An orbital transfer system for Shuttle applications, the Shuttle Compatible Orbit Transfer Subsystem (SCOTS) is described. SCOTS is designed to boost advanced communications satellites from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) using the Shuttle payload bay as a supporting platform system. The SCOTS design includes a 63-inch solid rocket motor which is attached to an interface ring. Guidance and control initialization prior to deployment is provided by an orbiter maneuver which aligns the SCOTS with a predetermined perigee-stage (PS) firing attitude. Payload deployment from the Orbiter payload bay is carried out by means of simple multispring push-offs. The ring interface of the SCOTS was designed to be compatible with the Ariane 4 launch system in order to provide maximum flexibility in launch vehicle selection. A line diagram illustrating the SCOTS configuration is given, and the basic SCOTS design parameters are summarized in a table.
NASA Astrophysics Data System (ADS)
Tomonari, Mutsumi; Ookubo, Norio; Takada, Toshikazu
1993-11-01
The off-diagonal component of the first-order hyperpolarizability tensor ? zxx of C 2v molecules, e.g. substituted polyynes and benzenes, has been calculated by a simplified sum-over-states method. The missing-orbital analysis of the calcualted results reveals that excitations from a 2 and b 2 orbitals contribute cooperatively to ? zxx, suggesting an insufficiency of the two-state model to describe ? zxx. Increasing the number of occupied a 2 orbitals enhances the magnitude of ? zxx. For the C 2v molecule with a 2 orbitals widely extended in the x direction, ? zxx can exceed ? zzz, as found in 9-amino-10-cyanoanthracene having a ? zxx about twice as large as ? zzz.
Sherman, David M.
1987-01-01
A molecular orbital description, based on X?-Scattered wave calculations on a (FeTiO10)14? cluster, is given for Fe2+ ? Ti4+ charge transfer transitions in minerals. The calculated energy for the lowest Fe2+ ? Ti4+ metal-metal charge transfer transition is 18040 cm?1 in reasonable agreement with energies observed in the optical spectra of Fe-Ti oxides and silicates. As in the case of Fe2+ ? Fe3+ charge transfer in mixed-valence iron oxides and silicates, Fe2+ ? Ti4+ charge transfer is associated with Fe-Ti bonding across shared polyhedral edges. Such bonding results from the overlap of the Fe(t 2g ) and Ti(t 2g ) 3d orbitals.
Zarycz, M Natalia C; Provasi, Patricio F
2015-02-01
The resonance-assisted hydrogen bond (HB) phenomenon has been studied theoretically by a localized molecular orbital (LMO) decomposition of the spin-spin coupling constants between atoms either involved or close to the O-H···O system of some ?-diketones and their saturated counterparts. The analysis, carried out at the level of the second-order polarization propagator approximation, shows that the contributions in terms of LMO to the paramagnetic spin orbital and the spin dipolar Ramsey terms proof the importance of the delocalized ?-electron structure supporting the idea of the existence of the resonance-assisted HB phenomenon phenomenon. The LMO contributions to the Fermi contact term indicate mainly the presence of the HB that may or not be linked to the ?-electrons. PMID:25266873
Diagonal Slices of 3D Young Diagrams in the Approach of Maya Diagrams
NASA Astrophysics Data System (ADS)
Cai, Li-Qiang; Wang, Li-Fang; Wu, Ke; Yang, Jie
2014-09-01
According to the correspondence between 2D Young diagrams and Maya diagrams and the relation between 2D and 3D Young diagrams, we construct 3D Young diagrams in the approach of Maya diagrams. Moreover, we formulate the generating function of 3D Young diagrams, which is the MacMahon function in terms of Maya diagrams.
... Blaser MJ, eds. In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, ... ER. Periorbital and orbital infections. In: Long SS, ed. Principles and Practice of Pediatric Infectious Diseases. 4th ed. ...
... appearance. One of the most common reasons is Graves’ disease, an autoimmune disorder that primarily affects the thyroid gland and the eye. If the eye is affected (Grave’s orbitopathy), there is an enlargement of the orbital ...
NSDL National Science Digital Library
This video from SpaceTEC National Aerospace Technical Education Center explains the mechanics of orbital dynamics and Newton's first law of motion. This three minute video is one of the aerospace certification readiness courses.
NASA Astrophysics Data System (ADS)
Jeeva Jasmine, N.; Thomas Muthiah, P.; Arunagiri, C.; Subashini, A.
2015-06-01
The FT-IR, FT-Raman, 1H, 13C NMR and UV-Visible spectral measurements of N?-hydroxy-pyrimidine-2-carboximidamide (HPCI) and complete analysis of the observed spectra have been proposed. DFT calculation has been performed and the structural parameters of the compound was determined from the optimized geometry with 6-311+G(d,p) basis set and giving energies, harmonic vibrational frequencies and force constants. The results of the optimized molecular structure are presented and compared with the experimental. The geometric parameters, harmonic vibrational frequencies and chemical shifts were compared with the experimental data of the molecule. The title compound, C5H6N4O, is approximately planar, with an angle of 11.04 (15)°. The crystal structure is also stabilized by intermolecular N-H⋯O, N-H⋯N, O-H⋯N, C-H⋯O hydrogen bond and offset ?-? stacking interactions. The influences of hydroxy and carboximidamide groups on the skeletal modes and proton chemical shifts have been investigated. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and band gap. The kinetic, thermodynamic stability and chemical hardness of the molecule have been determined. Complete NBO analysis was also carried out to find out the intermolecular electronic interactions and their stabilization energy. The thermodynamic properties like entropies and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structure.
Jasmine, N Jeeva; Muthiah, P Thomas; Arunagiri, C; Subashini, A
2015-06-01
The FT-IR, FT-Raman, (1)H, (13)C NMR and UV-Visible spectral measurements of N'-hydroxy-pyrimidine-2-carboximidamide (HPCI) and complete analysis of the observed spectra have been proposed. DFT calculation has been performed and the structural parameters of the compound was determined from the optimized geometry with 6-311+G(d,p) basis set and giving energies, harmonic vibrational frequencies and force constants. The results of the optimized molecular structure are presented and compared with the experimental. The geometric parameters, harmonic vibrational frequencies and chemical shifts were compared with the experimental data of the molecule. The title compound, C5H6N4O, is approximately planar, with an angle of 11.04 (15)°. The crystal structure is also stabilized by intermolecular N-H?O, N-H?N, O-H?N, C-H?O hydrogen bond and offset ?-? stacking interactions. The influences of hydroxy and carboximidamide groups on the skeletal modes and proton chemical shifts have been investigated. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and band gap. The kinetic, thermodynamic stability and chemical hardness of the molecule have been determined. Complete NBO analysis was also carried out to find out the intermolecular electronic interactions and their stabilization energy. The thermodynamic properties like entropies and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structure. PMID:25756689
UV-Diagram: A Voronoi Diagram for Uncertain Data
Cheng, Reynold Cheng Chun
the query point q is located in the Voronoi cell of O2, O2 is the nearest neighbor of q. Is it possible and business applications. In particular, we propose the Uncertain-Voronoi Diagram (or UV-diagram in short
NASA Technical Reports Server (NTRS)
2005-01-01
The structure of NASA's Mars Reconnaissance Orbiter spacecraft is constructed from composite panels of carbon layers over aluminum honeycomb, lightweight yet strong. This forms a basic structure or skeleton on which the instruments, electronics, propulsion and power systems can be mounted. The propellant tank is contained in the center of the orbiter's structure. This photo was taken at Lockheed Martin Space Systems, Denver, during construction of the spacecraft.
The Lenz Vector and Orbital Analog Computers
ERIC Educational Resources Information Center
Harter, W. G.
1976-01-01
Describes a single geometrical diagram based on the Lenz vector which shows the qualitative and quantitative features of all three types of Coulomb orbits. Explains the use of a simple analog computer with an overhead projector to demonstrate many of these effects. (Author/CP)
W-reps, nilp orbits, orbit method
Vogan, David
W-reps, nilp orbits, orbit method David Vogan Representation theory irr reps nilp orbits irr reps W reps nilp orbits W reps Explaining the arrows Remembrance of things past Weyl group representations, nilpotent orbits, and the orbit method David Vogan Department of Mathematics Massachusetts
Perturbations to the Hubble diagram
Thomas Schucker; Ilhem ZouZou
2005-11-17
We compute the linear responses of the Hubble diagram to small scalar perturbations in the Robertson-Walker metric and to small peculiar velocities of emitter and receiver. We discuss the monotonicity constraint of the Hubble diagram in the light of these responses.
ERIC Educational Resources Information Center
Barnum, Dennis W.
1982-01-01
Potential-pH diagrams show the domains of redoxpotential and pH in which major species are most stable. Constructing such diagrams provides students with opportunities to decide what species must be considered, search literature for equilibrium constants and free energies of formation, and practice in using the Nernst equation. (Author/JN)
Physiology Flow-Diagram Models
NSDL National Science Digital Library
PhD Sandra J Bruner (Polk Community College Biology)
2005-10-04
A set of physiology flow-diagrams for the cardiovascular system, cardiac auto-rhythmic cell, cardiac contractile cell, respiratory system, coagulation/hemostasis, digestive system, excretion, and autonomic nervous system. These flow-diagrams show cause-and-effect markup and have accompanying tutorials.
On knots in subdivergent diagrams
NASA Astrophysics Data System (ADS)
Kreimer, Dirk
1998-05-01
We investigate Feynman diagrams which are calculable in terms of generalized one-loop functions, and explore how the presence or absence of transcendentals in their counterterms reflects the entanglement of link diagrams constructed from them and explains unexpected relations between them.
Housecroft, C.E.; Fehiner, T.P.
1983-01-01
The electronic structure of HFe/sub 4/(CO)/sub 12/(eta/sup 2/-CH) has been examined by using the Fenske-Hall quantum chemical approach with a fragment analysis in terms of the butterfly metal cluster HFe/sub 4/(CO)/sub 12//sup +/ and the ligand CH/sup -/. The preference for the tilted (eta/sup 2/) orientation of the CH/sup -/ ligand over a symmetric vertical orientation can be explained in terms of the unusual properties of the frontier orbitals of the butterfly fragment. The eta/sup 2/ orientation causes the CH bond to be weakened in the complex because of the mixing of an empty CH antibonding orbital with a filled metal cluster orbital.
Phase diagram of half-doped manganites
Shu, Zhenghuang; Dong, Jinming; Xing, D. Y.
2001-06-01
The phase diagram of half-doped manganites which may consist of experimentally observed ferromagnetic (FM), A-,C-, and charge-exchange (CE)-type antiferromagnetic (AF) states is obtained in terms of a model which is based on double exchange via degenerate e{sub g} orbitals, the on-site Coulomb interaction (U), and the nearest-neighbor Coulomb interaction (V). We find that, because of the strong spatial anisotropy of the electron hoppings, the on-site Coulomb interaction has different effects on these magnetic order states. As a result, large values of U suppress the FM state and favor the A- and C-type AF states. Moreover, we show that it is the interplay between the on-site and nearest-neighbor Coulomb repulsions that stabilizes the CE phase and results in the charge ordering in the state.
Muthu, S; Renuga, S
2014-01-24
FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated. PMID:24096064
Himpsel, Franz J.
-ray absorption for a series of 3d metal porphyrins J. M. García-Lastra,1,2,a P. L. Cook,3 F. J. Himpsel,3 and A 20 October 2010 Porphyrins are widely used as dye molecules in solar cells. Knowing the energies in simpler or- ganic molecules. The frontier orbitals of the porphyrins par- ticularly their energies
NASA Technical Reports Server (NTRS)
Roberts, William W., Jr.; Stewart, Glen R.
1987-01-01
The role of orbit crowding and cloud-cloud collisions in the formation of GMCs and their organization in global spiral structure is investigated. Both N-body simulations of the cloud system and a detailed analysis of individual particle orbits are used to develop a conceptual understanding of how individual clouds participate in the collective density response. Detailed comparisons are made between a representative cloud-particle simulation in which the cloud particles collide inelastically with one another and give birth to and subsequently interact with young star associations and stripped down simulations in which the cloud particles are allowed to follow ballistic orbits in the absence of cloud-cloud collisions or any star formation processes. Orbit crowding is then related to the behavior of individual particle trajectories in the galactic potential field. The conceptual picture of how GMCs are formed in the clumpy ISMs of spiral galaxies is formulated, and the results are compared in detail with those published by other authors.
Szostak, Roman; Aubé, Jeffrey; Szostak, Michal
2015-08-21
Twisted amides containing nitrogen at the bridgehead position are attractive practical prototypes for the investigation of the electronic and structural properties of nonplanar amide linkages. Changes that occur during rotation around the N-C(O) axis in one-carbon-bridged twisted amides have been studied using ab initio molecular orbital methods. Calculations at the MP2/6-311++G(d,p) level performed on a set of one-carbon-bridged lactams, including 20 distinct scaffolds ranging from [2.2.1] to [6.3.1] ring systems, with the C?O bond on the shortest bridge indicate significant variations in structures, resonance energies, proton affinities, core ionization energies, frontier molecular orbitals, atomic charges, and infrared frequencies that reflect structural changes corresponding to the extent of resonance stabilization during rotation along the N-C(O) axis. The results are discussed in the context of resonance theory and activation of amides toward N-protonation (N-activation) by distortion. This study demonstrates that one-carbon-bridged lactams-a class of readily available, hydrolytically robust twisted amides-are ideally suited to span the whole spectrum of the amide bond distortion energy surface. Notably, this study provides a blueprint for the rational design and application of nonplanar amides in organic synthesis. The presented findings strongly support the classical amide bond resonance model in predicting the properties of nonplanar amides. PMID:26154179
NASA Astrophysics Data System (ADS)
Karthick, T.; Balachandran, V.; Perumal, S.; Nataraj, A.
2013-04-01
In this work, the vibrational characteristics of 2-chloro-5-(trifluoromethyl) aniline have been investigated and both the experimental and theoretical vibrational data indicate the presence of various functional groups within the title molecule. The influence of chlorine substituent on the vibrational wavenumbers of a molecule in comparison with aniline and trifluoromethyl aniline has been discussed in detail. The density functional theoretical (DFT) computations were performed at the B3LYP/6-31++G(3df,3pd)/6-31G(3df,3pd) levels to derive the optimized geometry, vibrational wavenumbers with IR and Raman intensities. Furthermore, the molecular orbital calculations such as; natural bond orbitals (NBOs) and HOMO-LUMO energy gap and mapped molecular electrostatic potential (MEP) surfaces were also performed with the same level of DFT. The temperature dependence thermodynamic parameters of a molecule were illustrated on the basis of their correlation graphs. The detailed interpretation of the vibrational spectra has been carried out with the aid of potential energy distribution (PED) results obtained from MOLVIB program. The delocalization of electron density in various constituents of the molecule has been discussed with the aid of NBO and HOMO-LUMO energy gap analysis.
Payload/orbiter contamination control requirement study
NASA Technical Reports Server (NTRS)
Bareiss, L. E.; Rantanen, R. O.; Ress, E. B.
1974-01-01
A study was conducted to determine and quantify the expected particulate and molecular on-orbit contaminant environment for selected space shuttle payloads as a result of major shuttle orbiter contamination sources. Individual payload susceptibilities to contamination are reviewed. The risk of payload degradation is identified and preliminary recommendations are provided concerning the limiting factors which may depend on operational activities associated with the payload/orbiter interface or upon independent payload functional activities. A basic computer model of the space shuttle orbiter which includes a representative payload configuration is developed. The major orbiter contamination sources, locations, and flux characteristics based upon available data have been defined and modeled.
Scattering Equations and Feynman Diagrams
Baadsgaard, Christian; Bourjaily, Jacob L; Damgaard, Poul H
2015-01-01
We show a direct matching between individual Feynman diagrams and integration measures in the scattering equation formalism of Cachazo, He and Yuan. The connection is most easily explained in terms of triangular graphs associated with planar Feynman diagrams in $\\phi^3$-theory. We also discuss the generalization to general scalar field theories with $\\phi^p$ interactions, corresponding to polygonal graphs involving vertices of order $p$. Finally, we describe how the same graph-theoretic language can be used to provide the precise link between individual Feynman diagrams and string theory integrands.
Scattering Equations and Feynman Diagrams
Christian Baadsgaard; N. E. J. Bjerrum-Bohr; Jacob L. Bourjaily; Poul H. Damgaard
2015-07-03
We show a direct matching between individual Feynman diagrams and integration measures in the scattering equation formalism of Cachazo, He and Yuan. The connection is most easily explained in terms of triangular graphs associated with planar Feynman diagrams in $\\phi^3$-theory. We also discuss the generalization to general scalar field theories with $\\phi^p$ interactions, corresponding to polygonal graphs involving vertices of order $p$. Finally, we describe how the same graph-theoretic language can be used to provide the precise link between individual Feynman diagrams and string theory integrands.
Shapira, D.
1988-01-01
Nuclear orbiting following collisions between sd and p shell nuclei is discussed. The dependence of this process on the real and imaginary parts of the nucleus-nucleus potential is discussed, as well as the evolution of the dinucleus toward a fully equilibrated fused system. 26 refs., 15 figs.
NSDL National Science Digital Library
This geometry lesson from Illuminations uses the model of the orbits of Mars and Earth relative to the sun to illustrate parametric equations. As an interdisciplinary learning activity, the material may be used in conjunction with astronomy lessons. An interactive applet and student questions are also included. The material is intended for grades 9-12 and should require 1 class period to complete.
NSDL National Science Digital Library
Coordinates for tracking the International Space Station and the Mir Space Station are available here from NASA's Johnson Space Center Flight Design and Dynamics Division. The Orbital Elements page offers real-time data for use in ground track plotting programs. The site cautions the data are for ground track plotting programs only and "should not be used for precise applications or analysis!"
Molecular orbitals of the oxocarbons (CO)n, n = 2-6. Why does (CO)4 have a triplet ground state?
Bao, Xiaoguang; Zhou, Xin; Flener Lovitt, Charity; Venkatraman, Amruth; Hrovat, David A; Gleiter, Rolf; Hoffmann, Roald; Borden, Weston Thatcher
2012-06-20
Cyclobutane-1,2,3,4-tetrone has been both predicted and found to have a triplet ground state, in which a b(2g) ? MO and an a(2u) ? MO are each singly occupied. The nearly identical energies of these two orbitals of (CO)(4) can be attributed to the fact that both of these MOs are formed from a bonding combination of C-O ?* orbitals in four CO molecules. The intrinsically stronger bonding between neighboring carbons in the b(2g) ? MO compared to the a(2u) ? MO is balanced by the fact that the non-nearest-neighbor, C-C interactions in (CO)(4) are antibonding in b(2g), but bonding in a(2u). Crossing between an antibonding, b(1g) combination of carbon lone-pair orbitals in four CO molecules and the b(2g) and a(2u) bonding combinations of ?* MOs is responsible for the occupation of the b(2g) and a(2u) MOs in (CO)(4). A similar orbital crossing occurs on going from two CO molecules to (CO)(2), and this crossing is responsible for the triplet ground state that is predicted for (CO)(2). However, such an orbital crossing does not occur on formation of (CO)(2n+1) from 2n + 1 CO molecules, which is why (CO)(3) and (CO)(5) are both calculated to have singlet ground states. Orbital crossings, involving an antibonding, b(1), combination of lone-pair MOs, occur in forming all (CO)(2n) molecules from 2n CO molecules. Nevertheless, (CO)(6) is predicted to have a singlet ground state, in which the b(2u) ? MO is doubly occupied and the a(2u) ? MO is left empty. The main reason for the difference between the ground states of (CO)(4) and (CO)(6) is that interactions between 2p AOs on non-nearest-neighbor carbons, which stabilize the a(2u) ? MO in (CO)(4), are much weaker in (CO)(6), due to the much larger distances between non-nearest-neighbor carbons in (CO)(6) than in (CO)(4). PMID:22687146
The Hertzsprung-Russell Diagram.
ERIC Educational Resources Information Center
Woodrow, Janice
1991-01-01
Describes a classroom use of the Hertzsprung-Russell diagram to infer not only the properties of a star but also the star's probable stage in evolution, life span, and age of the cluster in which it is located. (ZWH)
Time Temperature Transformation (TTT) Diagrams
Cambridge, University of
the TTT diagram of eutectoid steel. They determined pearlite and bainite portions whereas Cohen later% transformation to, say pearlite or bainite is considered as transformation start time and for 99% transformation
Computer calculation of distribution diagrams.
Maggiore, R; Musumeci, S; Sammartano, S
1976-01-01
A simple computer program (DISDI) has been developed for obtaining the distribution diagrams of the species in solutions containing up to one metal and two ligands. It has been compared with the programs COMICS and EQUIL. PMID:18961796
Atemporal diagrams for quantum circuits
Griffiths, Robert B.; Wu Shengjun; Yu Li; Cohen, Scott M.
2006-05-15
A system of diagrams is introduced that allows the representation of various elements of a quantum circuit, including measurements, in a form which makes no reference to time (hence 'atemporal'). It can be used to relate quantum dynamical properties to those of entangled states (map-state duality), and suggests useful analogies, such as the inverse of an entangled ket. Diagrams clarify the role of channel kets, transition operators, dynamical operators (matrices), and Kraus rank for noisy quantum channels. Positive (semidefinite) operators are represented by diagrams with a symmetry that aids in understanding their connection with completely positive maps. The diagrams are used to analyze standard teleportation and dense coding, and for a careful study of unambiguous (conclusive) teleportation. A simple diagrammatic argument shows that a Kraus rank of 3 is impossible for a one-qubit channel modeled using a one-qubit environment in a mixed state.
NSDL National Science Digital Library
Dexter Perkins
This short problem set works well as a group activity that can be completed in class. The purpose of the exercise is for students to begin to think about T-X phase diagrams and how they are interpreted. Along the way, students learn that text book authors sometimes make mistakes. The figure in the handout is from Winter's Petrology. But, Winter goofed and left some reactions off of the phase diagram.
NSDL National Science Digital Library
Vinther, Michael
Turning out flowcharts and diagrams for presentations can be quite a hassle, so it's nice to lean about the Diagram Designer application. With the program's interface, visitors can take advantage of the customizable object palette, slide show viewer, and the ability to plot mathematical expressions. This version also allows users to import various image file formats, such as jpeg and gif files. This version is compatible with computers running Windows 98 and newer.
Introduction to Ternary Phase Diagrams
NSDL National Science Digital Library
Dexter Perkins
This exercise is intended as a group exercise to help students learn the fundamentals of using ternary phase diagrams. It is a much better way for students to learn about the diagrams than to lecture to them. Good students will be able to walk through this with little assistance from the instructor.Weaker students will struggle and need help from peers or instructors. The entire exercise takes 1-2 hours for most.
NASA Astrophysics Data System (ADS)
Tomonari, Mutsumi; Ookubo, Norio; Takada, Toshikazu
1994-07-01
Missing-orbital analysis is applied to the diagonal and off-diagonal components of the first-order hyperpolarizability tensor ? evaluated by a simplified sum-over-states method. Various molecules assumed to have C2v symmetry are examined: benzene, pyridine-oxide and polyynes substituted with amino and either cyano or nitro groups. The missing-orbital analysis shows that the diagonal component ? zzz (z-axis in the donor-to-acceptor direction) for most of the molecules is essentially dominated by only one strongly charge-transfer excited configuration, and is describable by the conventional two-state model. For the off-diagonal component ? zxx, it is revealed that the excitations from a 2 and b 2 orbitals cooperatively make an important contribution. This indicates that, even for the molecules whose ? zzz is described well by the two-state model, ? zzz is necessarily modeled by a "multi-state" model consisting of the ground state and at least two excited configurations belonging to two different symmetries.
Echography - eye orbit; Ultrasound - eye orbit; Ocular ultrasonography; Orbital ultrasonography ... eye is numbed with medicine (anesthetic drops). The ultrasound wand (transducer) is placed against the front surface ...
Zimmerman, Paul M; Molina, Andrew R; Smereka, Peter
2015-07-01
Localized orbitals are representations of electronic structure, which are easier to interpret than delocalized, canonical orbitals. While unitary transformations from canonical orbitals into localized orbitals have long been known, existing techniques maximize localization without regard to coupling between orbitals. Especially in conjugated ? spaces, orbitals are collapsed by unitary localization procedures into nonintuitive, strongly interacting units. Over-localization decreases interpretability, results in large values of interorbital coupling, and gives unmeaningful diagonal Fock energies. Herein, we introduce orbitals of intermediate localization that span between canonical and fully localized orbitals. To within a specified error, these orbitals preserve the diagonal nature of the Fock matrix while still introducing significant locality. In systems composed of molecular fragments, ? spaces can be localized into weakly coupled units. Importantly, as the weakly coupled orbitals separate, highly coupled orbitals maintain their expected structure. The resulting orbitals therefore correspond well to chemical intuition and maintain accurate orbital energies, making this procedure unique among existing orbital localization techniques. This article focuses on the formation and physical analysis of orbitals that smoothly connect the known fully delocalized and fully localized limits. PMID:26156464
NASA Astrophysics Data System (ADS)
Zimmerman, Paul M.; Molina, Andrew R.; Smereka, Peter
2015-07-01
Localized orbitals are representations of electronic structure, which are easier to interpret than delocalized, canonical orbitals. While unitary transformations from canonical orbitals into localized orbitals have long been known, existing techniques maximize localization without regard to coupling between orbitals. Especially in conjugated ? spaces, orbitals are collapsed by unitary localization procedures into nonintuitive, strongly interacting units. Over-localization decreases interpretability, results in large values of interorbital coupling, and gives unmeaningful diagonal Fock energies. Herein, we introduce orbitals of intermediate localization that span between canonical and fully localized orbitals. To within a specified error, these orbitals preserve the diagonal nature of the Fock matrix while still introducing significant locality. In systems composed of molecular fragments, ? spaces can be localized into weakly coupled units. Importantly, as the weakly coupled orbitals separate, highly coupled orbitals maintain their expected structure. The resulting orbitals therefore correspond well to chemical intuition and maintain accurate orbital energies, making this procedure unique among existing orbital localization techniques. This article focuses on the formation and physical analysis of orbitals that smoothly connect the known fully delocalized and fully localized limits.
Z. Eker; O. Demircan; S. Bilir; Y. Karatas
2006-09-14
Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of log Jo - log P, log M - log P and log Jo-log M were formed from 119 CAB and 102 W UMa stars. The log Jo-log M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log Jo - log M diagram. Since orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio q, the rates of orbital angular momentum loss (dlog Jo/dt) and mass loss (dlog M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log Jo - log M diagram. Evolution of q for a mass loosing detached system is unknown unless mass loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of Jo and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6 Gyrs respectively.
Speedith: a diagrammatic reasoner for spider diagrams
Jamnik, Mateja
Speedith: a diagrammatic reasoner for spider diagrams Matej Urbas1 , Mateja Jamnik1 , Gem Stapleton for the language of spider diagrams. Spider diagrams are a well-known logic for which there is a sound and complete prover Speedith. Speedith's domain is the language of spider diagrams. It allows us to apply diagrammatic
Embedding Wellformed Euler Diagrams Peter Rodgers1
Kent, University of
Embedding Wellformed Euler Diagrams Peter Rodgers1 , Leishi Zhang1 , Gem Stapleton2 , Andrew Fish2.Zhang@kent.ac.uk, G.E.Stapleton@brighton.ac.uk, Andrew.Fish@brighton.ac.uk} Abstract Euler diagrams are collections applied to such examples, however Venn diagrams are a specific type of Euler diagram which represents all
Automatically Assessing Graph-Based Diagrams
ERIC Educational Resources Information Center
Thomas, Pete; Smith, Neil; Waugh, Kevin
2008-01-01
To date there has been very little work on the machine understanding of imprecise diagrams, such as diagrams drawn by students in response to assessment questions. Imprecise diagrams exhibit faults such as missing, extraneous and incorrectly formed elements. The semantics of imprecise diagrams are difficult to determine. While there have been…
Molecular-orbital study of late-fission times in deep-inelastic [sup 238]U+[sup 238]U collisions
Molitoris, J.D.; Meyerhof, W.E.; Stoller, C.; Anholt, R.; Spooner, D.W.; Moretto, L.G.; Sobotka, L.G.; McDonald, R.J.; Wozniak, G.J.; McMahan, M.A.; Blumenfeld, L.; Colonna, N.; Nessi, M.; Morenzoni, E. (Department of Physics, Stanford University, Stanford, California 94305 (United States) Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States) Laboratorium fuer Kernphysik, Eidgenoessische Technische Hochschule, CH-8093 Zuerich (Switzerland))
1993-02-01
The [ital U]-like [ital K]-vacancy production probability in 7.5-MeV/nucleon deep-inelastic [sup 238]U+[sup 238]U collisions has been measured for no-fission, single-fission, and double-fission exit channels. The results are interpreted using quasimolecular orbital correlations for diatomic and triatomic configurations. This leads to the determination of lower limits for the time scale for late fission of U-like products ([ge]8 and [ge]4 as) and their probability ([ge]77% and [ge]52%), at mean initial-excitation energies of [similar to]40 and [similar to]105 MeV, respectively.
Shimomura, Kenta; Muramatsu, Yasuji; Denlinger, Jonathan D.; Gullikson, Eric M.
2008-10-31
We used the DV-X alpha method to analyze the high-resolution soft X-ray emission and absorption spectra in the CK region of titanium carbide (TiC). The spectral profiles of the X-ray emission and absorption can be ssuscfucelly reproduced by the occupied and unoccupied density of states (DOS ), respectively, in the C2p orbitals of the center carbon atoms in a Ti62C63 cluster model, suggesting that the center carbon atom in a large cluster model expanded to the cubic-structured 53 (= 125) atoms provides sufficient DOS for the X-ray spectral analysis of rock-salt structured metal carbides.
Eric A. Bergshoeff; Alessio Marrani; Fabio Riccioni
2012-01-27
We complete the classification of half-supersymmetric branes in toroidally compactified IIA/IIB string theory in terms of representations of the T-duality group. As a by-product we derive a last wrapping rule for the space-filling branes. We find examples of T-duality representations of branes in lower dimensions, suggested by supergravity, of which none of the component branes follow from the reduction of any brane in ten-dimensional IIA/IIB string theory. We discuss the constraints on the charges of half-supersymmetric branes, determining the corresponding T-duality and U-duality orbits.
Michelotti, L.
1995-01-01
The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.
Accurate phase diagram of tetravalent DNA nanostars
NASA Astrophysics Data System (ADS)
Rovigatti, Lorenzo; Bomboi, Francesca; Sciortino, Francesco
2014-04-01
We evaluate, by means of molecular dynamics simulations employing a realistic DNA coarse-grained model, the phase behaviour and the structural and dynamic properties of tetravalent DNA nanostars, i.e., nanoconstructs completely made of DNA. We find that, as the system is cooled down, tetramers undergo a gas-liquid phase separation in a region of concentrations which, if the difference in salt concentration is taken into account, is comparable with the recently measured experimental phase diagram [S. Biffi, R. Cerbino, F. Bomboi, E. M. Paraboschi, R. Asselta, F. Sciortino, and T. Bellini, Proc. Natl. Acad. Sci. U.S.A. 110, 15633 (2013)]. We also present a mean-field free energy for modelling the phase diagram based on the bonding contribution derived by Wertheim in his studies of associating liquids. Combined with mass-action law expressions appropriate for DNA binding and a numerically evaluated reference free energy, the resulting free energy qualitatively reproduces the numerical data. Finally, we report information on the nanostar structure, e.g., geometry and flexibility of the single tetramer and of the collective behaviour, providing a useful reference for future small angle scattering experiments, for all investigated temperatures and concentrations.
NASA Astrophysics Data System (ADS)
Carter, Melvin Keith
2007-04-01
Cyclic voltammogram (CV) electrochemical measurements for pyrocatechol, resorcinol, hydroquinone, pyrogallol, and gallic acid in strong alkaline solution produced observable oxidation-reduction potentials for each hydroxy group present except for resorcinol. UV absorption spectra were also observed for the diluted solutions. Semi-empirical molecular orbital computations were conducted for these molecules of C2 v point group symmetry to determine the character and energies to aid interpretation of the experimental results. CV oxidation removed a ?-electron by a radiationless ?-?* transition followed by an electron shift from a negative oxygen to the positive aromatic ?-system indicated by an observable ?-?* transition. Simple semi-empirical computations correlated with measured excited electronic states during electron transfer.
Ito, K.; Lee, G. H.; Harada, K.; Suzuno, M.; Suemasu, T.; Takeda, Y.; Saitoh, Y.; Ye, M.; Kimura, A.; Akinaga, H.
2011-03-07
10-nm-thick {gamma}{sup '}-Fe{sub 4}N films were grown epitaxially on LaAlO{sub 3}(001) and MgO(001) substrates by molecular beam epitaxy using solid Fe and a radio-frequency NH{sub 3} plasma. The lattice mismatch of these substrates to {gamma}{sup '}-Fe{sub 4}N is 0% and 11%, respectively. Spin and orbital magnetic moments of these {gamma}{sup '}-Fe{sub 4}N epitaxial films were deduced by x-ray magnetic circular dichroism measurements at 300 K. The total magnetic moments are almost the same for the two substrates, that is, 2.44{+-}0.06 {mu}{sub B} and 2.47{+-}0.06 {mu}{sub B}, respectively. These values are very close to those predicted theoretically, and distinctively larger than that for {alpha}-Fe.
Dinolfo, Peter H; Coropceanu, Veaceslav; Brédas, Jean-Luc; Hupp, Joseph T
2006-10-01
The ligand-centered mixed-valence (LCMV) properties of two supramolecular complexes are reported: triangular prisms of the form ([Re(CO)3]2X)3-mu,mu',mu' '-[tPyTz]2, where X is 2,2'-bisbenzimidazolate (1) or a pair of benzylthiols (2), and tPyTz is tri-(4-pyridyl)-1,3,5-triazine. Cyclic voltammetry demonstrates that the redox-accessible bridging ligands, tPyTz, are reduced in sequential, one-electron reactions. The singly reduced prisms, which represent an unusual type of mixed-valence compound in which the tPyTz ligands themselves are the redox centers, show intense, broad intervalance transfer (IT) bands in the NIR, consistent with highly coupled MV species. Electroabsorption (Stark spectroscopy) measurements reveal small dipole moment changes associated with intervalence excitation (|Deltamu12| = 0.30 +/- 0.02 eA for 1- and 0.48 +/- 0.02 eA for 2-), as well as noncollinear transition dipole moment (mu12) and dipole moment change vectors (zeta approximately 45 degrees ). DFT electronic structure calculations support this unusual result, along with a through-space electronic interaction mechanism. The neutral complexes (D3h symmetry) possess doubly degenerate, but spatially distinct, LUMO and LUMO+ orbitals. The orbital degeneracy of the tPyTz ligands is lifted in the MV forms, resulting in nonsymmetrical charge redistribution within the molecules upon on optical IT. PMID:17002321
NASA Astrophysics Data System (ADS)
Long, Sheila Ann Thibeault
The H-H, C-H, and C-C spin-spin coupling constants were calculated by the finite-perturbation, intermediate -neglect-of-differential-overlap method using the Fermi contact interaction for benzene, naphthalene, biphenyl, anthracene, phenanthrene, and pyrene. The calculations were made using both the actual and the average molecular geometries. For all six of these molecules, the agreements between the calculated and the experimental coupling constants were comparable to those previously reported for other, predominantly smaller, molecules. The actual molecular geometries always gave the correct relative order of values for the H-H coupling constants, whereas the average molecular geometries did not always do so. The magnitudes, but not the signs, of the calculated coupling constants were sensitive to small changes in molecular geometry. The results were the best (next best) for the H-H (C-H) coupling constants. In addition the H-H, C-H, N-H, C-C, and N-C spin -spin coupling constants were calculated in a similar manner for pyridine, pyridazine, pyrimidine, pyrazine, s-triazine, quinoline, quinoxaline, phthalazine, benzo g quinoxaline, and benzo b phenazine. The agreements between the theoretical and the experimental values were comparable to those for the polycyclic aromatic hydrocarbons.
Pseudohaptic interaction with knot diagrams
NASA Astrophysics Data System (ADS)
Weng, Jianguang; Zhang, Hui
2012-07-01
To make progress in understanding knot theory, we need to interact with the projected representations of mathematical knots, which are continuous in three dimensions (3-D) but significantly interrupted in the projective images. One way to achieve such a goal is to design an interactive system that allows us to sketch two-dimensional (2-D) knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress in this direction. Pseudohaptics that simulate haptic effects using pure visual feedback can be used to develop such an interactive system. We outline one such pseudohaptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2-D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a physically reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudohaptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of which the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudohaptic four-dimensional (4-D) visualization system that simulates the continuous navigation on 4-D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2-D knot diagrams of 3-D knots and 3-D projective images of 4-D mathematical objects.
The phase diagram and transport properties for hydrogen-helium fluid planets
NASA Technical Reports Server (NTRS)
Stevenson, D. J.; Salpeter, E. E.
1977-01-01
The properties of pure hydrogen and helium are examined, taking into account metallic hydrogen, molecular hydrogen, and the molecular-metallic transition. Metallic hydrogen-helium mixtures are considered along with molecular hydrogen-helium mixtures, the total phase diagram, and minor constituents, including deuterium. The transport properties of the metallic and the molecular phase are also discussed, giving attention to electrical conductivity, thermal conductivity, viscosity, self-diffusion, interdiffusion, radiative opacity, and second-order transport coefficients.
Precision orbit determination at the NASA Goddard Space Flight Center
NASA Technical Reports Server (NTRS)
Putney, B.; Kolenkiewicz, R.; Smith, D.; Dunn, P.; Torrence, M. H.
1990-01-01
This paper describes the GEODYN computer program developed by the Geodynamics Branch at the NASA Goddard Space Flight Center and outlines the procedure for accurate satellite orbit and tracking-data analyses. The capabilities of the program allow the development of gravity fields as large as 90 by 90, and a complete modeling of tidal parameters. It is also feasible to numerically integrate a continuous orbit of a satellite such as Lageos for up to 12 years. The evolution of the orbit can be studied, and, by comparison with locally determined orbits, force model improvements can be made. The GEODYN flow diagrams are presented.
Orbital order of spinless fermions near an optical Feshbach resonance
Hauke, Philipp [ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la Tecnologia, E-08860 Castelldefels (Spain); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Zhao, Erhai [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030 (United States); Goyal, Krittika; Deutsch, Ivan H. [Center for Quantum Information and Control (CQuIC), and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Liu, W. Vincent [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Lewenstein, Maciej [ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la Tecnologia, E-08860 Castelldefels (Spain); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)
2011-11-15
We study the quantum phases of a three-color Hubbard model that arises in the dynamics of the p-band orbitals of spinless fermions in an optical lattice. Strong, color-dependent interactions are induced by an optical Feshbach resonance. Starting from the microscopic scattering properties of ultracold atoms, we derive the orbital exchange constants at 1/3 filling on the cubic optical lattice. Using this, we compute the phase diagram in a Gutzwiller ansatz. We find phases with ''axial orbital order'' in which p{sub z} and p{sub x}+ip{sub y} (or p{sub x}-ip{sub y}) orbitals alternate.
The Brauer loop scheme and orbital varieties
Allen Knutson; Paul Zinn-Justin
2014-10-02
A. Joseph invented multidegrees in [Jo84] to study orbital varieties, which are the components of an orbital scheme, itself constructed by intersecting a nilpotent orbit with a Borel subalgebra. Their multidegrees, known as Joseph polynomials, give a basis of a (Springer) representation of the Weyl group. In the case of the nilpotent orbit $\\{ M^2=0 \\}$, the orbital varieties can be indexed by noncrossing chord diagrams in the disc. In this paper we study the normal cone to the orbital scheme inside this nilpotent orbit $\\{ M^2 = 0 \\}$. This gives a better-motivated construction of the Brauer loop scheme we introduced in [KZJ07], whose components are indexed by all chord diagrams (now possibly with crossings) in the disc. The multidegrees of its components, the Brauer loop varieties, were shown to reproduce the ground state of the Brauer loop model in statistical mechanics [DFZJ06]. Here, we reformulate and slightly generalize these multidegrees in order to express them as solutions of the rational quantum Knizhnik--Zamolodchikov equation associated to the Brauer algebra. In particular, the vector of the multidegrees satisfies two sets of equations, corresponding to the $e_i$ and $f_i$ generators of the Brauer algebra. We describe here the geometric meaning of both $e_i$ and $f_i$ equations in our slightly extended setting. We also describe the corresponding actions at the level of orbital varieties: while only the $e_i$ equations make sense directly on the Joseph polynomials, the $f_i$ equations also appear if one introduces a broader class of varieties. We explain the connection of the latter with matrix Schubert varieties.
NASA Astrophysics Data System (ADS)
Borsten, L.; Duff, M. J.; Ferrara, S.; Marrani, A.; Rubens, W.
2012-04-01
We study both the large and small U-duality charge orbits of extremal black holes appearing in D=5 and D=4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated “moduli spaces.” After recalling N=8 maximal supergravity, we consider N=2 and N=4 theories coupled to an arbitrary number of vector multiplets, as well as N=2 magic, STU, ST2 and T3 models. While the STU model may be considered as part of the general N=2 sequence, albeit with an additional triality symmetry, the ST2 and T3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit nonzero elements of rank 3, respectively. Finally, we also consider minimally coupled N=2, matter-coupled N=3, and pure N=5 theories.
Phase Diagrams for Sonoluminescing Bubbles
Sascha Hilgenfeldt; Detlef Lohse; Michael P. Brenner
1996-01-01
Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration vs forcing pressure state space and also in the ambient radius vs gas concentration and vs forcing pressure state spaces.
INCONEL 718: A solidification diagram
G. A. Knorovsky; M. J. Cieslak; T. J. Headley; A. D. Romig; W. F. Hammetter
1989-01-01
As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are used in
Index of Animated Phase Diagrams
NSDL National Science Digital Library
Kenneth E Windom
This is a collection of animated phase diagrams by Kenneth Windom at Iowa State University. These short Power Point animations can be used to illustrate equilibrium crystallization concepts. There are slide shows for plagioclase feldspars (albite and anorthite); forsterite, diopside and anorthite; forsterite, enstatite and silica; and diopside and anorthite.
NSDL National Science Digital Library
M Johnson
2013-10-02
This response answers a posted question, "What is your favorite warm-up suited for all grade levels?". The response details a Venn Diagram warm-up that can be used with any grade level and modified to fit most math topics.
Extron 8 port Video/Audio Switch WAVE Camera Telesynergy v3 Wiring Diagram ISDN T1/PRI Module CTRLR 0 Legend: S-Video Audio VGA DVI USB RS-232 Serial Microphone Ethernet Planar C5i AMD Exam Cam Canon Document Camera Olympus BX51 Sony DVD Recorder JVC
Animated Diagram: Sedimentary Rock Identification
NSDL National Science Digital Library
This Flash-enabled diagram provides a scheme for sedimentary rock identification accompanied by pop-up images of the rocks. Rolling the mouse over highlighted boxes links texture, grain size, composition, and map symbols to images of a variety of sedimentary rocks. The animation is downloadable.
Zhao, Dong-Xia; Yang, Zhong-Zhi
2014-05-15
In recent years, the basic problem of understanding chemical bonding, nonbonded, and/or van der Waals interactions has been intensively debated in terms of various theoretical methods. We propose and construct the potential acting on one electron in a molecule-molecular orbital (PAEM-MO) diagram, which draws the PAEM inserted the MO energy levels with their major atomic orbital components. PAEM-MO diagram is able to show clear distinction of chemical bonding from nonbonded and/or vdW interactions. The rule for this is as follows. Along the line connecting two atoms in a molecule or a complex, the existence of chemical bonding between these two atoms needs to satisfy two conditions: (a) a critical point of PAEM exists and (b) PAEM barrier between the two atoms is lower in energy than the occupied major valence-shell bonding MO which contains in-phase atomic components (positive overlap) of the two considered atoms. In contrast to the chemical bonding, for a nonbonded interaction or van der Waals interaction between two atoms, both conditions (a) and (b) do not be satisfied at the same time. This is demonstrated and discussed by various typical cases, particularly those related to helium atom and H-H bonding in phenanthrene. There are helium bonds in HHeF and HeBeO molecules, whereas no H-H bonding in phenanthrene. The validity and limitation for this rule is demonstrated through the investigations of the curves of the PAEM barrier top and MO energies versus the internuclear distances for He2 , H2 , and He2 (+) systems. PMID:24615750
NASA Astrophysics Data System (ADS)
Boulanger, Thierry; Vercauteren, Daniel P.; Evrard, Guy; Durant, Francois
1989-09-01
The molecular structure of hydroxy-3? imino-16 5?-aza-17 androstanone-11, R5135, a potent steroidic GABA-A antagonist, has been optimized using the semi-empirical MNDO method. Its crystal structure has been solved by X-ray diffraction. Theoretical and experimental structural results are compared. Using both geometries, ab initio MO calculations have been applied within the STO-3G basis set to quantify the electronic structure. The results of the Mulliken charge population analysis show a good agreement between the computed atomic charges and interatomic overlap populations for both structures. These values are finally compared with those reported earlier for GABA.
NSDL National Science Digital Library
Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.
Mapping the topological phase diagram of multiband semiconductors with supercurrents.
San-Jose, Pablo; Prada, Elsa; Aguado, Ramón
2014-04-01
We show that Josephson junctions made of multiband semiconductors with strong spin-orbit coupling carry a critical supercurrent Ic that contains information about the nontrivial topology of the system. In particular, we find that the emergence and annihilation of Majorana bound states in the junction is reflected in strong even-odd effects in Ic at small junction transparency. This effect allows for a mapping between Ic and the topological phase diagram of the junction, thus providing a dc measurement of its topology. PMID:24745449
NASA Astrophysics Data System (ADS)
Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A.; Johnson, Paul A.; Ayers, Paul W.; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri
2014-06-01
We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.
Sciortino, Francesco
Phase diagram of amorphous solid water: Low-density, high-density, and very-high-density amorphous the phase diagram of amorphous solid water by performing molecular dynamics simulations using the extended low-density amorphous LDA , high-density amorphous HDA , and very-high density amorphous VHDA ices
guidelines for binary phase diagram assessment
H. Okamoto; T. B. Massalski
1993-01-01
The recent publication of Binary Alloy Phase Diagrams,2nd ed, [90Mas] and our extensive screening of phase diagram graphics\\u000a for this edition has revealed many phase diagram features, which while not explicitly violating phase diagram rules, are to\\u000a a lesser or greater extent unlikely to represent thermodynamically acceptable conditions. In two previous papers, several\\u000a thermodynamically improbable features or boundaries in binary
NASA Astrophysics Data System (ADS)
Packwood, Daniel M.; Oniwa, Kazuaki; Jin, Tienan; Asao, Naoki
2015-04-01
Organic crystals have unique charge transport properties that lie somewhere between delocalised band-type transport and localised hopping transport. In this paper, we use a stochastic tight-binding model to explore how dynamical disorder in organic crystals affects charge transport. By analysing the model in terms of Feynman diagrams (virtual processes), we expose the crucial role of correlated dynamical disorder to the charge transport dynamics in the model at short times in the order of a few hundred femtoseconds. Under correlated dynamical disorder, the random motions of molecules in the crystal allow for low-energy "bonding"-type interactions between neighboring molecular orbitals can persist over long periods of time. On the other hand, the dependence of charge transport on correlated dynamical disorder also tends to localize the charge, as correlated disorder cannot persist far in space. This concept of correlation may be the "missing link" for describing the intermediate regime between band transport and hopping transport that occurs in organic crystals.
Packwood, Daniel M; Oniwa, Kazuaki; Jin, Tienan; Asao, Naoki
2015-04-14
Organic crystals have unique charge transport properties that lie somewhere between delocalised band-type transport and localised hopping transport. In this paper, we use a stochastic tight-binding model to explore how dynamical disorder in organic crystals affects charge transport. By analysing the model in terms of Feynman diagrams (virtual processes), we expose the crucial role of correlated dynamical disorder to the charge transport dynamics in the model at short times in the order of a few hundred femtoseconds. Under correlated dynamical disorder, the random motions of molecules in the crystal allow for low-energy "bonding"-type interactions between neighboring molecular orbitals can persist over long periods of time. On the other hand, the dependence of charge transport on correlated dynamical disorder also tends to localize the charge, as correlated disorder cannot persist far in space. This concept of correlation may be the "missing link" for describing the intermediate regime between band transport and hopping transport that occurs in organic crystals. PMID:25877586
Zitare, Ulises; Alvarez-Paggi, Damián; Morgada, Marcos N; Abriata, Luciano A; Vila, Alejandro J; Murgida, Daniel H
2015-08-10
The CuA site of cytochrome?c oxidase is a redox hub that participates in rapid electron transfer at low driving forces with two redox cofactors in nearly perpendicular orientations. Spectroscopic and electrochemical characterizations performed on first and second-sphere mutants have allowed us to experimentally detect the reversible switching between two alternative electronic states that confer different directionalities to the redox reaction. Specifically, the M160H variant of a native CuA shows a reversible pH transition that allows to functionally probe both states in the same protein species. Alternation between states exerts a dramatic impact on the kinetic redox parameters, thereby suggesting this effect as the mechanism underlying the efficiency and directionality of CuA electron transfer in?vivo. These findings may also prove useful for the development of molecular electronics. PMID:26118421
Hero's journey in bifurcation diagram
NASA Astrophysics Data System (ADS)
Monteiro, L. H. A.; Mustaro, P. N.
2012-06-01
The hero's journey is a narrative structure identified by several authors in comparative studies on folklore and mythology. This storytelling template presents the stages of inner metamorphosis undergone by the protagonist after being called to an adventure. In a simplified version, this journey is divided into three acts separated by two crucial moments. Here we propose a discrete-time dynamical system for representing the protagonist's evolution. The suffering along the journey is taken as the control parameter of this system. The bifurcation diagram exhibits stationary, periodic and chaotic behaviors. In this diagram, there are transition from fixed point to chaos and transition from limit cycle to fixed point. We found that the values of the control parameter corresponding to these two transitions are in quantitative agreement with the two critical moments of the three-act hero's journey identified in 10 movies appearing in the list of the 200 worldwide highest-grossing films.
"Isomorphs" in liquid state diagrams
Nicoletta Gnan; Thomas B. Schrøder; Ulf R. Pedersen; Nicholas P. Bailey; Jeppe C. Dyre
2009-05-04
A liquid is termed strongly correlating if its virial and potential energy thermal equilibrium fluctuations in the NVT ensemble are more than 90% correlated [Phys. Rev. Lett. 100, 015701 (2008)]. The fluctuations of a strongly correlating liquid are well approximated by those of an inverse power-law intermolecular potential. Building on this fact we here define "isomorphic lines" in the state diagram of a strongly correlating liquid. It is shown from computer simulations of the Kob-Andersen binary Lennard-Jones liquid that no aging is associated with jumps between two isomorphic points. Isomorphic state points have the same excess entropy, the same reduced average relaxation time, the same (reduced) dynamics, and the same scaled radial distribution functions. Finally we calculate the equation for isomorphs in the virial / potential energy diagram for Lennard-Jones type liquids and show that all such 12-6 liquids have the same isomorphs; these may be scaled into a master isomorph.
INCONEL 718: A solidification diagram
G. A. Knorovsky; M. J. Cieslak; T. J. Headley; A. D. Romig; W. F. Hammetter
1989-01-01
As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to\\u000a generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and\\u000a scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are\\u000a used in
Annotera diagram Frklaring av kurvor
Annotera diagram Â· FÃ¶rklaring av kurvor: legend('Funktion 1','Funktion 2')! Â· Grekiska tecken procedurer Â· BerÃ¤kning av integraler Â· NollstÃ¤llen, max- och minvÃ¤rden Â· Polynomhantering Repetition;Delar av matriser Â· Index till en matris Ã¤r vektorer! Â· A(2,[2 3 4]) ger en vektor bestÃ¥ende av element
Phase Diagrams in Chemical Engineering: Application to
Paris-Sud XI, Université de
19 Phase Diagrams in Chemical Engineering: Application to Distillation and Solvent Extraction Procédés, Fontainebleau 1South Africa 2France 1. Introduction By definition, a phase diagram in physical, and composition of the system, a phase diagram provides a graphical visualization of the effects of these system
Unjustified Assumptions Based on Diagrams in Geometry
ERIC Educational Resources Information Center
Dvora, Tali; Dreyfus, Tommy
2004-01-01
We investigated unjustified assumptions made by students when proving geometric statements. Geometric statements can be presented with a diagram or without. Diagrams can be accurate or sketchy. Unjustified assumptions may originate in an accompanying diagram. We thus asked whether the way in which a statement is presented has an effect on…
INCONEL 718: A solidification diagram
NASA Astrophysics Data System (ADS)
Knorovsky, G. A.; Cieslak, M. J.; Headley, T. J.; Romig, A. D.; Hammetter, W. F.
1989-10-01
As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are used in conjunction with solidification theory to generate data points for this diagram. The important features of the diagram are an austenite (?)/Laves phase eutectic which occurs at ?19.1 wt pct Nb between austenite containing ?9.3 wt pct Nb and a Laves phase which contains ?22.4 wt pct Nb. The distribution coefficient for Nb was found to be ?0.5. The solidification sequence of INCONEL 718 was found to be (1) proeutectic ?, followed by (2) a ?/NbC eutectic at ?1250°C, followed by (3) continued ? solidification, followed by (4) a ?/Laves phase eutectic at ?1200°C. An estimate of the volume fraction eutectic is made using the Scheil solidification model, and the fraction of each phase in the eutectic is calculated via the lever rule. These are compared with experimentally determined values and found to be in good agreement.
Causal diagrams in systems epidemiology
2012-01-01
Methods of diagrammatic modelling have been greatly developed in the past two decades. Outside the context of infectious diseases, systematic use of diagrams in epidemiology has been mainly confined to the analysis of a single link: that between a disease outcome and its proximal determinant(s). Transmitted causes ("causes of causes") tend not to be systematically analysed. The infectious disease epidemiology modelling tradition models the human population in its environment, typically with the exposure-health relationship and the determinants of exposure being considered at individual and group/ecological levels, respectively. Some properties of the resulting systems are quite general, and are seen in unrelated contexts such as biochemical pathways. Confining analysis to a single link misses the opportunity to discover such properties. The structure of a causal diagram is derived from knowledge about how the world works, as well as from statistical evidence. A single diagram can be used to characterise a whole research area, not just a single analysis - although this depends on the degree of consistency of the causal relationships between different populations - and can therefore be used to integrate multiple datasets. Additional advantages of system-wide models include: the use of instrumental variables - now emerging as an important technique in epidemiology in the context of mendelian randomisation, but under-used in the exploitation of "natural experiments"; the explicit use of change models, which have advantages with respect to inferring causation; and in the detection and elucidation of feedback. PMID:22429606
Diagram, a Learning Environment for Initiation to Object-Oriented Modeling with UML Class Diagrams
ERIC Educational Resources Information Center
Py, Dominique; Auxepaules, Ludovic; Alonso, Mathilde
2013-01-01
This paper presents Diagram, a learning environment for object-oriented modelling (OOM) with UML class diagrams. Diagram an open environment, in which the teacher can add new exercises without constraints on the vocabulary or the size of the diagram. The interface includes methodological help, encourages self-correcting and self-monitoring, and…
NASA Astrophysics Data System (ADS)
Oyamada, Takayuki; Tachikawa, Masanori
2014-08-01
We have performed multi-component full-configuration interaction calculations to investigate the nature of chemical bonding of [LiH;e+] at the small and large internuclear distance. We discuss the importance of geometrical changes in positronic compounds induced by a positron attachment in terms of the virial theorem, with a comparison of the adiabatic- and vertical-positron affinity (PA). The systematic improvement of the PA values achieved by optimisation of (i) the molecular geometry and (ii) the positronic basis centre is also discussed. The stable dissociation channel of [LiH;e+] is compared with the ionic- and neutral-dissociation channels of its parent molecule LiH through the analysis of the potential energy curve and the electronic and positronic densities. The vertical PA as a function of is also presented, which is the difference between the potential energy curve of the parent molecule (LiH ? Li + H) and its positronic compound ([LiH; e+] ? Li + [H; e+]). Unlike the preceding study of [M. Mella et al., J. Chem. Phys. 113, 6154 (2000)], it took more than bohr to converge the vertical PA due to the long-range ionic bonding interaction.
Govindasamy, P; Gunasekaran, S
2014-10-24
In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000-450cm(-1) and 4000-50cm(-1), respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (?H). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported. The oscillator's strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed. PMID:25459716
Effectiveness of Using Computer-Assisted Instruction in Teaching the Shapes of Atomic Orbitals.
ERIC Educational Resources Information Center
Shubbar, Khalil E.
2003-01-01
Investigates the effect of computer-assisted instruction (CAI) when used as a supplement to classroom instruction to improve secondary school students' understanding of orbital shapes. Results indicate that the CAI approach enhanced student learning and helped them figure out cues portrayed in diagrams of atomic orbitals. (Contains 22 references.)…
NASA Astrophysics Data System (ADS)
Yamada, Yurika; Kita, Yukiumi; Tachikawa, Masanori; Towler, Mike D.; Needs, Richard J.
2014-03-01
Energy thresholds for dissociation channels of positronic alkali-metal hydrides, [XH;e+] (X = Li, Na, and K), to XH + e+(positron dissociation), XH+ + Ps (positronium dissociation), and X+ + [H-;e+] (positronic hydride ion dissociation) have been calculated using quantum Monte Carlo and high-level ab initio molecular orbital methods, and including quantum zero-point vibrational energy of all of the particles. As the atomic number of X increases from Li to K, the dissociation energy to XH + e+ increases because the dipole moment of XH increases with the atomic number of X, while the dissociation energy to XH+ + Ps decreases. The energy threshold for the ionic dissociation to X+ + [H-;e+] is also reduced, and we obtain 0.975 (3) eV, 0.573 (12) eV, and 0.472 (19) eV for [LiH;e+], [NaH;e+], and [KH;e+], respectively, for this channel. Our results strongly support the conclusion that, among these three channels, the lowest energy dissociation for [XH;e+] is the pathway to X+ + [H-;e+], where X = Li, Na, and K.
Bourgeois, Scott K.
2010-07-14
with larger orbits far above the Earth's surface, e.g. a Geostationary Orbit. Camera systems mounted on satellites can provide an eff ective way to observe these objects. Using a satellite with a speci c orbit relative to the RSO's orbit, one can passively...
Phase diagram of Janus Particles
Francesco Sciortino; Achille Giacometti; Giorgio Pastore
2009-11-16
We deeply investigate a simple model representative of the recently synthesized Janus particles, i.e. colloidal spherical particles whose surface is divided into two areas of different chemical composition. When the two surfaces are solvophilic and solvophobic, these particles constitute the simplest example of surfactants. The phase diagram includes a colloidal-poor (gas) colloidal-rich (liquid) de-mixing region, which is progressively suppressed by the insurgence of micelles, providing the first model where micellization and phase-separation are simultaneously observed. The coexistence curve is found to be negatively sloped in the temperature-pressure plane, suggesting that Janus particles can provide a colloidal system with anomalous thermodynamic behavior.
NSDL National Science Digital Library
Douglas Hamilton
This site offers two programs to illustrate how orbits work. The Orbital Elements calculator contains animations to see how the appearance of an orbit depends on the values of the orbital elements which include distance from the Sun, eccentricity, pericenter location and anomaly. This is available in two or three dimensions. The Solar System allows users to watch several planets in our Solar System simultaneously orbit the Sun. An additional object (asteroid or comet) is present and users change the orbital parameters to see what types of orbits are possible for this object.
NASA Astrophysics Data System (ADS)
Wakayama, Masayuki; Kunihiro, Teiji; Muroya, Shin; Nakamura, Atsushi; Nonaka, Chiho; Sekiguchi, Motoo; Wada, Hiroaki; Scalar Collaboration
2015-05-01
We study the possible significance of four-quark states in the isosinglet scalar mesons (JP C=0++ , I =0 ) by performing two-flavor full lattice QCD simulations on an 83×16 lattice using the improved gauge action and the clover-improved Wilson quark action. In particular, we evaluate the propagators of molecular and tetraquark operators together with singly disconnected diagrams. In the computation of the singly disconnected diagrams we employ the Z2-noise method with the truncated eigenmode approach. We show that the quark loops given by the disconnected diagrams play an essential role in propagators of tetraquark and molecular operators.
Determination of cellulose crystallinity from powder diffraction diagrams.
Lindner, Benjamin; Petridis, Loukas; Langan, Paul; Smith, Jeremy C
2015-02-01
One-dimensional (1D) (spherically averaged) powder diffraction diagrams are commonly used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. This leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrils with crystalline segments as amorphous. The reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 67-73, 2015. PMID:25269646
Quantum quasicrystals and other exotic states of spin-orbit coupled dipolar bosons
NASA Astrophysics Data System (ADS)
Gopalakrishnan, Sarang; Wilson, Ryan; Anderson, Brandon; Lev, Benjamin; Clark, Charles; Martin, Ivar; Demler, Eugene
2014-03-01
We study dipolar Bose gases in which the bosons experience a Rashba spin-orbit coupling. We show that the degenerate dispersion minimum due to the spin-orbit coupling, combined with the long-range dipolar interaction, can stabilize a rich phase diagram including a number of exotic phases, such as a quantum quasicrystal (in the quasi-2D limit) and a meron state (in the 3D limit), as one tunes the strength of the dipolar interaction and the spin-orbit coupling. We discuss specific level schemes for exploring this phase diagram using ultracold dysprosium.
NASA Astrophysics Data System (ADS)
Brzezicki, Wojciech; Ole?, Andrzej M.; Cuoco, Mario
2015-01-01
We investigate the changes in spin and orbital patterns induced by magnetic transition-metal ions without an orbital degree of freedom doped in a strongly correlated insulator with spin-orbital order. In this context, we study the 3 d ion substitution in 4 d transition-metal oxides in the case of 3 d3 doping at either 3 d2 or 4 d4 sites, which realizes orbital dilution in a Mott insulator. Although we concentrate on this doping case as it is known experimentally and more challenging than other oxides due to finite spin-orbit coupling, the conclusions are more general. We derive the effective 3 d -4 d (or 3 d -3 d ) superexchange in a Mott insulator with different ionic valencies, underlining the emerging structure of the spin-orbital coupling between the impurity and the host sites, and demonstrate that it is qualitatively different from that encountered in the host itself. This derivation shows that the interaction between the host and the impurity depends in a crucial way on the type of doubly occupied t2 g orbital. One finds that in some cases, due to the quench of the orbital degree of freedom at the 3 d impurity, the spin and orbital order within the host is drastically modified by doping. The impurity either acts as a spin defect accompanied by an orbital vacancy in the spin-orbital structure when the host-impurity coupling is weak or favors doubly occupied active orbitals (orbital polarons) along the 3 d -4 d bond leading to antiferromagnetic or ferromagnetic spin coupling. This competition between different magnetic couplings leads to quite different ground states. In particular, for the case of a finite and periodic 3 d atom substitution, it leads to striped patterns either with alternating ferromagnetic or antiferromagnetic domains or with islands of saturated ferromagnetic order. We find that magnetic frustration and spin degeneracy can be lifted by the quantum orbital flips of the host, but they are robust in special regions of the incommensurate phase diagram. Orbital quantum fluctuations modify quantitatively spin-orbital order imposed by superexchange. In contrast, the spin-orbit coupling can lead to anisotropic spin and orbital patterns along the symmetry directions and cause a radical modification of the order imposed by the spin-orbital superexchange. Our findings are expected to be of importance for future theoretical understanding of experimental results for 4 d transition-metal oxides doped with 3 d3 ions. We suggest how the local or global changes of the spin-orbital order induced by such impurities could be detected experimentally.
Structural Phase Diagram of Ca
Vega, D.; Polla, G.; Leyva, A. G.; Konig, P.; Lanza, H.; Esteban, A.; Aliaga, H.; Causa, M. T.; Tovar, M.; Alascio, B.
2001-02-01
To help the understanding of the physical behavior of Ca{sub 1-x}Y{sub x}MnO{sub 3}, its phase diagram in the whole x concentration range was investigated taking into account the stability of phases and the possible coexistence of different structural phases. By careful analysis of powder X-ray diffraction (XRD) patterns, we were able to observe the following phase diagram: (i) Orthorhombic phases were detected both in the region of 0 {le} x {le} 0.25 (O type phase with Ca site twelve fold coordinated) and in the region of 0.5 {le} x {le} 0.75 (O' type phase with Ca site ninefold coordinated). (ii) Phase segregation for 0.25 {le} x {le} 0.5 and for x > 0.75 that have not been reported previously, hexagonal YMnO{sub 3} segregates as a separate phase for x > 0.75, and for 0.25 {le} x {le} 0.5 the coexistence of Ca{sub 0.75}Y{sub 0.25}MnO{sub 3} (O) and Ca{sub 0.5}Y{sub 0.5}MnO{sub 3} (O') have to be included in the refinement for it to converge.
C. J. H Schutte
2001-01-01
An analysis of the shapes of the MOs obtained during a Born–Oppenheimer scan of the PE of ArH+ by MP4\\/6-311++G(3df,3dp) MO calculations, allows the successive disengagement of bonding orbitals to be determined. This clearly shows how the different MOs influence the vibrational–rotational properties of ArH+ and underlines the importance of the concept of orbital following for molecular spectroscopy and the
Binary alloy phase diagrams requiring further studies
H. Okamoto; T. B. Massalski
1994-01-01
Binary Alloy Phase Diagrams , 2nd ed. 90Mas, covering ?3000 systems and ?2200 phase diagrams, is the most current compilation of binary systems. However,\\u000a ?500 of them include thermodynamically unlikely features. These problems are classified into more than 30 groups, and a few\\u000a typical examples are shown for each group. If a phase diagram shows an improbable feature, it implies
Process Flow Diagrams for Training and Operations
NASA Astrophysics Data System (ADS)
Venter, Jacobus
This paper focuses on the use of process flow diagrams for training first responders who execute search and seizure warrants at electronic crime scenes. A generic process flow framework is presented, and the design goals and layout characteristics of process flow diagrams are discussed. An evaluation of the process flow diagrams used in training courses indicates that they are beneficial to first responders performing searches and seizures, and they speed up investigations, including those conducted by experienced personnel.
A multi-component rose diagram
NASA Astrophysics Data System (ADS)
Robson, R. M.
1994-07-01
Rose diagrams and circular histograms have long been standard graphics for the display of directional data. One problem using the traditional graphics is the limited number of attributes that may be incorporated into the one display. A hybrid of the rose diagram and circular histogram allows several attributes of directional data to be displayed simultaneously. This hybrid graphic has been termed the multi-component rose diagram.
The box diagram in Yukawa theory
Bernard L. G. Bakker; Jorn K. Boomsma; Chueng-Ryong Ji
2006-10-30
We present a light-front calculation of the box diagram in Yukawa theory. The covariant box diagram is finite for the case of spin-1/2 constituents exchanging spin-0 particles. In light-front dynamics, however, individual time-ordered diagrams are divergent. We analyze the corresponding light-front singularities and show the equivalence between the light-front and covariant results by taming the singularities.
Pilot-wave hydrodynamics in a rotating frame: Exotic orbits
Oza, Anand U.; Harris, Daniel M.; Rosales, Rodolfo R.; Bush, John W. M.; Wind-Willassen, Øistein
2014-08-15
We present the results of a numerical investigation of droplets walking on a rotating vibrating fluid bath. The drop's trajectory is described by an integro-differential equation, which is simulated numerically in various parameter regimes. As the forcing acceleration is progressively increased, stable circular orbits give way to wobbling orbits, which are succeeded in turn by instabilities of the orbital center characterized by steady drifting then discrete leaping. In the limit of large vibrational forcing, the walker's trajectory becomes chaotic, but its statistical behavior reflects the influence of the unstable orbital solutions. The study results in a complete regime diagram that summarizes the dependence of the walker's behavior on the system parameters. Our predictions compare favorably to the experimental observations of Harris and Bush [“Droplets walking in a rotating frame: from quantized orbits to multimodal statistics,” J. Fluid Mech. 739, 444–464 (2014)].
Variable stars across the observational HR diagram
Laurent Eyer; Nami Mowlavi
2007-12-21
An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude diagram, is also presented. Some of the progresses performed in the field of variable stars during the last decade are briefly summarized, and future projects that will improve our knowledge of variable stars are mentioned.
Solving Hybrid Influence Diagrams with Deterministic Variables
Li, Yijing
2012-01-01
We describe a framework and an algorithm for solving hybrid influence diagrams with discrete, continuous, and deterministic chance variables, and discrete and continuous decision variables. A continuous chance variable in an influence diagram is said to be deterministic if its conditional distributions have zero variances. The solution algorithm is an extension of Shenoy's fusion algorithm for discrete influence diagrams. We describe an extended Shenoy-Shafer architecture for propagation of discrete, continuous, and utility potentials in hybrid influence diagrams that include deterministic chance variables. The algorithm and framework are illustrated by solving two small examples.
Classical 3-loop 2-body diagrams
Barak Kol; Ruth Shir
2013-07-30
As part of the study of the two-body problem in Einstein's gravity, the fourth post-Newtonian order (4PN) of the two-body effective action is being computed presently by both effective field theory (EFT) methods and others. Diagrams with 3 (or 4) classical loops appear to be a significant obstacle. In this paper we develop a method to compute such 3-loop diagrams and demonstrate it through a specific diagram. We reduce the classical diagrams through shrinking the body worldlines to a form more familiar in Quantum Field Theory. A key ingredient in the evaluation is the Integration By Parts method for Feynman integrals.
A Regime Diagram for Subduction
NASA Astrophysics Data System (ADS)
Stegman, D. R.; Farrington, R.; Capitanio, F. A.; Schellart, W. P.
2009-12-01
Regime diagrams and associated scaling relations have profoundly influenced our understanding of planetary dynamics. Previous regime diagrams characterized the regimes of stagnant-lid, small viscosity contrast, transitional, and no-convection for temperature-dependent (Moresi and Solomatov, 1995), and non-linear power law rheologies (Solomatov and Moresi, 1997) as well as stagnant-lid, sluggish-lid, and mobile-lid regimes once the finite strength of rock was considered (Moresi and Solomatov, 1998). Scalings derived from such models have been the cornerstone for parameterized models of thermal evolution of rocky planets and icy moons for the past decade. While such a theory can predict the tectonic state of a planetary body, it is still rather incomplete in regards to predicting tectonics. For example, the mobile-lid regime is unspecific as to how continuous lithospheric recycling should occur on a terrestrial planet. Towards this goal, Gerya et al., (2008) advanced a new regime diagram aiming to characterize when subduction would manifest itself as a one-sided or two-sided downwelling and either symmetric or asymmetric. Here, we present a regime diagram for the case of a single-sided, asymmetric type of subduction (most Earth-like type). Using a 3-D numerical model of a free subduction, we describe a total of 5 different styles of subduction that can possibly occur. Each style is distinguished by its upper mantle slab morphology resulting from the sinking kinematics. We provide movies to illustrate the different styles and their progressive time-evolution. In each regime, subduction is accommodated by a combination of plate advance and slab rollback, with associated motions of forward plate velocity and trench retreat, respectively. We demonstrate that the preferred subduction mode depends upon two essential controlling factors: 1) buoyancy of the downgoing plate and 2) strength of plate in resisting bending at the hinge. We propose that a variety of subduction regimes are generated primarily as a product of two mechanisms. The first mechanism is that of the competition between the weight of the slab and the strength of the plate, which can be understood in terms of the applied bending moment, and this competition results in a particular radius of curvature (for which we provide a simple scaling theory). The second mechanism is the interaction between the slab and the more viscous lower mantle, which produces each regime's distinct slab morphology. Thus, the emergence of five distinct styles of subduction is a direct consequence of the presence of the modest barrier to flow into the lower mantle. Although only 2 of these styles presently operate on Earth, the possibility exists that other modes may have been the predominant mode in the past. Based on these models, we propose that the lithosphere is the primary factor in describing key elements of the plate tectonics system over time, rather than the convecting mantle. We discuss the various factors that may have influenced secular changes in Earth's tectonic behavior, some of which may have interesting consequences for the geochemical evolution of the Earth.
PHASE DIAGRAMS and MACROMOLECULAR STABILITY
Middaugh, C. Russell
2006-10-26
2: back squares) and isolated P-domain (empty circles) were plotted as a function of pH. 36 Other examples of Empirical Phase Diagrams Botulinum A Holotoxin pH T e m p e r a t u r e 3 4 5 6 7 8 20 30 40 50 60 70 80 37 Botulinum A Neurotoxin pH T e... temperature (typically 2- 90 C, 2-5 C intervals) B = alter pH (typically 3, 4, 5, 6, 7, 8) C = alter buffer (e.g., phosphate [1-3, 6-8, 11-13], citrate [2-4, 4-6, 5- 6.5], acetate [4-6], glycine [7-9], tris [7-9]) D = alter ionic strength (e.g., 0-3 M Na...
Phase diagram of ammonium nitrate.
Dunuwille, Mihindra; Yoo, Choong-Shik
2013-12-01
Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO-AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N2, N2O, and H2O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV' transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C. PMID:24320387
Phase diagram of ammonium nitrate
NASA Astrophysics Data System (ADS)
Dunuwille, Mihindra; Yoo, Choong-Shik
2013-12-01
Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO-AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N2, N2O, and H2O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV' transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.
Phase diagram of ammonium nitrate
NASA Astrophysics Data System (ADS)
Dunuwille, M.; Yoo, C. S.
2014-05-01
Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.
Hubble's diagram and cosmic expansion.
Kirshner, Robert P
2004-01-01
Edwin Hubble's classic article on the expanding universe appeared in PNAS in 1929 [Hubble, E. P. (1929) Proc. Natl. Acad. Sci. USA 15, 168-173]. The chief result, that a galaxy's distance is proportional to its redshift, is so well known and so deeply embedded into the language of astronomy through the Hubble diagram, the Hubble constant, Hubble's Law, and the Hubble time, that the article itself is rarely referenced. Even though Hubble's distances have a large systematic error, Hubble's velocities come chiefly from Vesto Melvin Slipher, and the interpretation in terms of the de Sitter effect is out of the mainstream of modern cosmology, this article opened the way to investigation of the expanding, evolving, and accelerating universe that engages today's burgeoning field of cosmology. PMID:14695886
Hubble's diagram and cosmic expansion
NASA Astrophysics Data System (ADS)
Kirshner, Robert P.
2004-01-01
Edwin Hubble's classic article on the expanding universe appeared in PNAS in 1929 [Hubble, E. P. (1929) Proc. Natl. Acad. Sci. USA 15, 168-173]. The chief result, that a galaxy's distance is proportional to its redshift, is so well known and so deeply embedded into the language of astronomy through the Hubble diagram, the Hubble constant, Hubble's Law, and the Hubble time, that the article itself is rarely referenced. Even though Hubble's distances have a large systematic error, Hubble's velocities come chiefly from Vesto Melvin Slipher, and the interpretation in terms of the de Sitter effect is out of the mainstream of modern cosmology, this article opened the way to investigation of the expanding, evolving, and accelerating universe that engages today's burgeoning field of cosmology.
Phase Diagram of Ammonium Nitrate
NASA Astrophysics Data System (ADS)
Dunuwille, Mihindra; Yoo, Choong-Shik
2013-06-01
Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. The present study has been supported by the U.S. DHS under Award Number 2008-ST-061-ED0001.
Al-Mogren, Muneerah M; Alaghaz, Abdel-Nasser M A; Ebrahem, Ebrahem A
2013-10-01
Eight mononuclear chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of Schiff's base ligand were synthesized and determined by different physical techniques. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytic in nature. All the eight metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The analytical data helped to elucidate the structure of the metal complexes. The Schiff base is found to act as tridentate ligand using N2O donor set of atoms leading to an octahedral geometry for the complexes around all the metal ions. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption method, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. The Schiff base and their complexes have been screened for their antibacterial activity against bacterial strains [Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024), Bacillis subtilis (RCMB010063), Proteous vulgaris (RCMB 010085), Klebsiella pneumonia (RCMB 010093) and Shigella flexneri (RCMB 0100542)] and fungi [(Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035)] by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligand. PMID:23831943
NASA Astrophysics Data System (ADS)
Al-Mogren, Muneerah M.; Alaghaz, Abdel-Nasser M. A.; Elbohy, Salwa A. H.
2013-10-01
Eight mononuclear chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of Schiff's base ligand were synthesized and determined by different physical techniques. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytic in nature. All the eight metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The analytical data helped to elucidate the structure of the metal complexes. The Schiff base is found to act as tridentate ligand using N2O donor set of atoms leading to an octahedral geometry for the complexes around all the metal ions. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption method, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. The Schiff base and their complexes have been screened for their antibacterial activity against bacterial strains [Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024), Bacillis subtilis (RCMB010063), Proteous vulgaris (RCMB 010085), Klebsiella pneumonia (RCMB 010093) and Shigella flexneri (RCMB 0100542)] and fungi [(Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035)] by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligand.
Marckert, Jean-François
Random Young diagrams Jack measure Jack characters Structure constants Central limit theorem for random Young diagrams with respect to Jack measure (joint work with Valentin Féray) Maciej Dolga LIAFA Jack measure Jack characters Structure constants Young diagrams Definition A partition is a finite non
Orbital Mechanics Analysis Program
NASA Technical Reports Server (NTRS)
Simon, W. C.; Jankowski, S. C.; Hughes, T. B.
1985-01-01
Orbital Mechanics Analysis Program provides engineers with simple tool for analysis or synthesis of any orbital maneuvering function involving vehicle and target. Program useful in such applications as proximity operations and rendezvous maneuvers.
NASA Astrophysics Data System (ADS)
Inagaki, Satoshi
Cyclic orbital interactions are contained in non-cyclic conjugation as well as cyclic conjugation. For effective interactions, the orbitals are required to meet simultaneously the phase continuity conditions: (1) out of phase relation between electron-donating orbitals; (2) in phase relation between electron-accepting orbitals and between electron-donating and -accepting orbitals. The orbital phase theory is applicable to diverse chemical phenomena of non-cyclic conjugate systems, e.g., relative stabilities of non-cyclic isomers, and selectivities of the reactions through non-cyclic transition structures. The orbital phase theory also includes the rules for cyclic systems, i.e., the Wooward-Hoffmann rule for stereoselection of organic reactions and the Hueckel 4n + 2? electron rule for aromatic molecules. Derivation and applications of the orbital phase theory are reviewed.
NSDL National Science Digital Library
This applet shows 3-dimensional representations of hydrogenic orbital surfaces. Orbital phase is shown by the different colors. The images are rotatable and scalable. This applet will run very slowly on older, slower machines.
NASA Technical Reports Server (NTRS)
Babb, Gus R.; Stump, William R.
1986-01-01
Parking orbits for a manned Mars mission are examined for ease of access to the Martian moons. Delta V plots for a variety of burns versus elliptical orbit apoapsis are included. A high elliptical orbit (24 hour period, 500 km periapsis, 20 to 30 deg. inclination) minimizes delta V to the Martian moons and Mars orbit insertion (MOI) and trans-Earth injection (TEI) delta Vs.
Chord Diagrams and Coxeter Links Eriko Hironaka
Chord Diagrams and Coxeter Links Eriko Hironaka February 28, 2003 Abstract This paper presents a construction of #12;bered links (K; #6;) out of chord diagrams L. Let be the incidence graph of L. Under; S). Lehmer's problem is solved for the monodromy of these Coxeter links. 1 1 Introduction A chord
Chord Diagrams and Coxeter Links Eriko Hironaka
Chord Diagrams and Coxeter Links Eriko Hironaka April 23, 2003 Abstract This paper presents a construction of #12;bered links (K; #6;) out of chord diagrams L. Let be the incidence graph of L. Under; S). Lehmer's problem is solved for the monodromy of these Coxeter links. 1 1 Introduction A chord
Diagrams in Biology1 Laura Perini
McBurney, Peter
1 Diagrams in Biology1 Laura Perini Department of Philosophy Pomona College Abstract Biologists by their frequent use, diagrams are important tools for biologists. They are used during the process of research, as biologists plan experiments with flow charts, and draw models to represent hypotheses for consideration
Formalizing Spider Diagrams Joseph (Yossi) Gil
Kent, University of
Formalizing Spider Diagrams Joseph (Yossi) Gil£ Department of Computer Science Technion--IIT, Haifa software systems by non-mathematicians, spider di- agrams are a visual language that generalizes the popu and expressiveness while retaining intuitiveness. In this extended abstract we describe spider diagrams from
Zone Diagrams: Existence, Uniqueness and Algorithmic Challenge
Matousek, Jiri
Zone Diagrams: Existence, Uniqueness and Algorithmic Challenge Tetsuo Asano # School of Information Science, JAIST 1Â1 Asahidai, Nomi, Ishikawa 923Â1292 Japan JiÅ¸ râ?? ï¿½ MatouÅ¸ sek ## Department of Applied University Aramaki Aza Aoba, AobaÂku, Sendai 980Â8579 Japan Abstract A zone diagram is a new variation
Voronoi diagrams based on convex distance functions
L. Paul Chew
1985-01-01
We present an “expanding waves” view of Voronoi diagrams that allows such diagrams to be defined for very general metrics and for distance measures that do not qualify as metrics. If a pebble is dropped into a still pond, circular waves move out from the point of impact. If n pebbles are dropped simultaneously, the places where wave fronts meet
Feynman Diagrams, Differential Reduction, and Hypergeometric Functions
M. Yu. Kalmykov; V. V. Bytev; Bernd A. Kniehl; B. F. L. Ward; S. A. Yost
2009-04-15
We will present some (formal) arguments that any Feynman diagram can be understood as a particular case of a Horn-type multivariable hypergeometric function. The advantages and disadvantages of this type of approach to the evaluation of Feynman diagrams is discussed.
DECISION DIAGRAMS AND PASS TRANSISTOR LOGIC SYNTHESIS
De Micheli, Giovanni
DECISION DIAGRAMS AND PASS TRANSISTOR LOGIC SYNTHESIS V. Bertacco S. Minato P. Verplaetse L. Benini by ARPA, under grant No. DABT63-95-C-0049. #12;Decision Diagrams and Pass Transistor Logic Synthesis V transistors and domino logic. The synthesis of these cells is based on BDD and ZBDD representations
The QCD phase diagram at finite density
Christian Schmidt; Zoltan Fodor; Sandor Katz
2005-10-18
We study the density of states method to explore the phase diagram of the chiral transition on the tempeature and quark chemical potential plane. Four quark flavours are used in the analysis. Though the method is quite expensive small lattices show an indication for a triple-point connecting three different phases on the phase diagram.
Jee, Eunkyoung
}@dependable.kaist.ac.kr, 2 psh@kari.re.kr FBD(Function Block Diagram) FBD . PLC FBD C by the Korea Science and Engineering Foundation(KOSEF) through the Advanced Information Technology Research], . , , . RLL(Relay Ladder Logic) , #12; Function Block Diagrams 5 . PLC
Phase diagram of a random tiling quasicrystal
Weixiong Li; Michael Widom
1992-01-01
We study the phase diagram of a two-dimensional random tiling model for quasicrystals. At proper concentrations the model has 8-fold rotational symmetry. Landau theory correctly gives most of the qualitative features of the phase diagram, which is in turn studied in detail numerically using a transfer matrix approach. We find that the system can enter the quasicrystal phase from many
Mining and integration of pathway diagrams from imaging data
Kozhenkov, Sergey; Baitaluk, Michael
2012-01-01
Motivation: Pathway diagrams from PubMed and World Wide Web (WWW) contain valuable highly curated information difficult to reach without tools specifically designed and customized for the biological semantics and high-content density of the images. There is currently no search engine or tool that can analyze pathway images, extract their pathway components (molecules, genes, proteins, organelles, cells, organs, etc.) and indicate their relationships. Results: Here, we describe a resource of pathway diagrams retrieved from article and web-page images through optical character recognition, in conjunction with data mining and data integration methods. The recognized pathways are integrated into the BiologicalNetworks research environment linking them to a wealth of data available in the BiologicalNetworks' knowledgebase, which integrates data from >100 public data sources and the biomedical literature. Multiple search and analytical tools are available that allow the recognized cellular pathways, molecular networks and cell/tissue/organ diagrams to be studied in the context of integrated knowledge, experimental data and the literature. Availability: BiologicalNetworks software and the pathway repository are freely available at www.biologicalnetworks.org. Contact: baitaluk@sdsc.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:22267504
Phase diagram of a reentrant gel of patchy particles
Roldán-Vargas, Sándalo; Smallenburg, Frank; Sciortino, Francesco; Kob, Walter
2013-12-28
We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.
High pressure phase diagram of MgO
NASA Astrophysics Data System (ADS)
French, Martin; Cebulla, Daniel; Redmer, Ronald
2015-06-01
In order to improve the understanding of the interior of super-Earths (planets in the range of 1-10 Earth masses) and other exoplanets, ab inito calculations for the planetary materials and the equation of state (EOS) and phase diagram of planetary materials are needed. A typical representative is MgO, which is an abundant material in the Earth's mantle and is also expected to be important for the mantle of exoplanets as well as for the rocky cores of gas giants such as Jupiter. Using ab initio molecular dynamic simulations, we have determined the phase diagram for MgO up to 20000 K and 1.5 TPa. In particular, the transition from the solid to the molten salt has been studied using diffusion analyses and pair distribution functions. The transition from the B1 to the B2 structure in solid MgO is determined by calculating the respective free enthalpies. The phase diagram of MgO is constructed based on accurate EOS data. We compare with results from (decaying) shock and ramp compression experiments and theoretical calculations for the B1-B2 and the liquid-solid transition line.
Phase diagram of a reentrant gel of patchy particles
NASA Astrophysics Data System (ADS)
Roldán-Vargas, Sándalo; Smallenburg, Frank; Kob, Walter; Sciortino, Francesco
2013-12-01
We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.
Phase diagram of a reentrant gel of patchy particles.
Roldán-Vargas, Sándalo; Smallenburg, Frank; Kob, Walter; Sciortino, Francesco
2013-12-28
We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation. PMID:24387399
How to Draw Energy Level Diagrams in Excitonic Solar Cells.
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. PMID:26279547
ERIC Educational Resources Information Center
Pauling, Linus; McClure, Vance
1970-01-01
Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)
Reading fitness landscape diagrams through HSAB concepts
NASA Astrophysics Data System (ADS)
Vigneresse, Jean-Louis
2014-10-01
Fitness landscapes are conceived as range of mountains, with local peaks and valleys. In terms of potential, such topographic variations indicate places of local instability or stability. The chemical potential, or electronegativity, its value changed of sign, carries similar information. In addition to chemical descriptors defined through hard-soft acid-base (HSAB) concepts and computed through density functional theory (DFT), the principles that rule chemical reactions allow the design of such landscape diagrams. The simplest diagram uses electrophilicity and hardness as coordinates. It allows examining the influence of maximum hardness or minimum electrophilicity principles. A third dimension is introduced within such a diagram by mapping the topography of electronegativity, polarizability or charge exchange. Introducing charge exchange during chemical reactions, or mapping a third parameter (f.i. polarizability) reinforces the information carried by a simple binary diagram. Examples of such diagrams are provided, using data from Earth Sciences, simple oxides or ligands.
Hybridization of Rydberg Electron Orbitals by Molecule Formation
NASA Astrophysics Data System (ADS)
Gaj, A.; Krupp, A. T.; Ilzhöfer, P.; Löw, R.; Hofferberth, S.; Pfau, T.
2015-07-01
The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between a Rydberg electron and a polarizable ground-state atom in an ultracold gas. In the nondegenerate case, the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.
Hybridization of Rydberg electron orbitals by molecule formation
Gaj, A; Ilzhöfer, P; Löw, R; Hofferberth, S; Pfau, T
2015-01-01
The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between Rydberg electron and polarizable ground state atom in an ultracold gas. In the nondegenerate case the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate, how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.
Environmental dynamics at orbital altitudes
NASA Technical Reports Server (NTRS)
Karr, G. R.
1976-01-01
The work reported involved the improvement of aerodynamic theory for free molecular and transition flow regimes. The improved theory was applied to interpretation of the dynamic response of objects traveling through the atmosphere. Satellite drag analysis includes analysis methods, atmospheric super rotation effects, and satellite lift effects on orbital dynamics. Transition flow regimes were studied with falling sphere data and errors resulting in inferred atmospheric parameters from falling sphere techniques. Improved drag coefficients reveal considerable error in previous falling sphere data. The drag coefficient has been studied for the entire spectrum of Knudsen Number and speed ratio, with particular emphasis on the theory of the very low-speed ratio regime.
Heterogeneous Proofs: Spider Diagrams meet Higher-Order Provers
Jamnik, Mateja
Heterogeneous Proofs: Spider Diagrams meet Higher-Order Provers Matej Urbas and Mateja Jamnik or spider diagrams. We provide a mechanisation of the theory of abstract spider diagrams and establish diagrammatic reasoning systems for example, spider diagrams [6] and constraint diagrams [3]. Consequently
NASA Technical Reports Server (NTRS)
Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim
2012-01-01
Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.
Phase diagram of ammonium nitrate
Dunuwille, Mihindra; Yoo, Choong-Shik
2013-12-07
Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ?} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.
NASA Astrophysics Data System (ADS)
Starrett, C. E.; Daligault, J.; Saumon, D.
2015-01-01
An approach to simulating warm and hot dense matter that combines density-functional-theory-based calculations of the electronic structure to classical molecular dynamics simulations with pair interaction potentials is presented. The method, which we call pseudoatom molecular dynamics, can be applied to single-component or multicomponent plasmas. It gives equation of state and self-diffusion coefficients with an accuracy comparable to orbital-free molecular dynamics simulations but is computationally much more efficient.
First-Principles Phase Diagram for Ce-Th System
Landa, A; Soderlind, P; Ruban, A; Vitos, L; Pourovskii, L
2004-05-11
Ab initio total energy calculations based on the exact muffin-tin orbitals (EMTO) theory are used to determine the high pressure and low temperature phase diagram of Ce and Th metals as well as the Ce{sub 43}Th{sub 57} disordered alloy. The compositional disorder for the alloy is treated in the framework of the coherent potential approximation (CPA). Equation of state for Ce, Th and Ce{sub 43}Th{sub 57} has been calculated up to 1 Mbar in good comparison with experimental data: upon compression the Ce-Th system undergoes crystallographic phase transformation from an fcc to a bct structure and the transition pressure increases with Th content in the alloy.
Magnetic phase diagram of F2PNNNO
NASA Astrophysics Data System (ADS)
Takano, Yasu
2007-03-01
2-[2',6',-difluoro-4'-(N-tert-butyl-N-oxyamino)phenyl]-4,4,5,5-tetramethyl-4,5- dihydro-1H-imidazol-1-oxyl 3-oxide, F2PNNNO for short, is an organic molecule containing two unpaired electrons. Residing in the N-tert-butyl nitroxide and nitronyl nitroxide groups, the two S=1/2 spins of these electrons are ferromagnetically coupled with an exchange constant of 407 K. In a crystal, two neighboring F2PNNNO molecules form a pair in which the nitronyl-nitroxide spins are coupled antiferromagnetically with an exchange constant of 67 K. The magnetism of F2PNNNO is that of the spin tetramers of these molecular pairs, which in turn are antiferromagnetically coupled with an exchange constant of 7.4 K [1]. Specific-heat and magnetocaloric-effect measurements reveal a highly symmetric boundary of the ordered phase in the phase diagram, with a lower critical field of Hc1=9.46 T and an upper critical field of Hc2=15.37 T. The ordering temperature Tc obeys a power law Tc ˜(H-Hc1)^? near Hc1, with the exponent ? approaching 2/3 in the low-temperature limit, indicative of a Bose-Einstein condensation (BEC) of |S, Sz>=|1,1> tetramers. Near the upper critical field Hc2, where one expects a BEC of singlet |0,0> tetramers in the ``vacuum'' comprising |1,1> tetramers, the corresponding power-law exponent remains around 0.4. Remarkably, the temperature dependence of the specific heat indicates that the magnon dispersion is independent of magnetic field between the two critical fields. This work is in collaboration with H. Tsujii, B. Andraka, Y. Hosokoshi, and K. Inoue. [1] Y. Hosokoshi et al., Phys. Rev. B 60, 12924 (1999).
Viking satellite orbit determination
NASA Technical Reports Server (NTRS)
Hildebrand, C. E.; Christensen, E. J.; Boggs, D. H.; Born, G. H.; Hokikian, H.; Jordan, J. F.; Howard, W. B.
1977-01-01
During the summer of 1976, the two Viking spacecraft, each consisting of an orbiter-lander combination, were inserted into orbit about Mars. The paper describes the experiences of the Viking Satellite Orbit Determination Team in determining Mars centered ephemerides of the orbiters and positions of the landers from the two-way Doppler and range data, and synthesizes the different phases of the navigation plan which involves pre-flight modeling and error analysis for all Viking navigation functions from launch through landing. The problem of initial orbit convergence is solved by using DPODP's (Double Precision Orbit Determination Program) square-root batch data filter, and gravity models for both Viking I and Viking II were produced from the combination of short arc estimates. The importance of synchronous Viking orbits (with the rotational period of Mars) is stressed and future extended missions of the spacecraft are outlined.
Orbits and Double Max Neunhffer
NeunhÃ¶ffer, Max
Orbits and Double Cosets Max NeunhÃ¶ffer Introduction GAP examples The orbit algorithm Computing the stabiliser Double cosets Orbits by suborbits Storing suborbits Orbit-by-Suborbits Finding homomorphisms Problems Orbits and Double Cosets Max NeunhÃ¶ffer University of St Andrews GAC 2010, Allahabad #12;Orbits
Farantos, Stavros C.
Saddle-node states in the spectra of HCO and DCO: a periodic orbit classi®cation of vibrational isotopomer DCO are analyzed in terms of periodic orbits (POs) and continuation/bifurcation diagrams. Both by counting the nodes along the three coordinate axes; therefore, many of the assignments given in Table 1
Algorithmic Identification for Wings in Butterfly Diagrams.
NASA Astrophysics Data System (ADS)
Illarionov, E. A.; Sokolov, D. D.
2012-12-01
We investigate to what extent the wings of solar butterfly diagrams can be separated without an explicit usage of Hale's polarity law as well as the location of the solar equator. Two algorithms of cluster analysis, namely DBSCAN and C-means, have demonstrated their ability to separate the wings of contemporary butterfly diagrams based on the sunspot group density in the diagram only. Here we generalize the method for continuous tracers, give results concerning the migration velocities and presented clusters for 12 - 20 cycles.
Counting planar diagrams with various restrictions
NASA Astrophysics Data System (ADS)
't Hooft, Gerard
1999-01-01
Explicit expressions are considered for the generating functions concerning the number of planar diagrams with given numbers of 3- and 4-point vertices. It is observed that planar renormalization theory requires diagrams with restrictions, in the sense that one wishes to omit 'tadpole' insertions and 'seagull' insertions; at a later stage also self-energy insertions are to be removed, and finally also the dressed 3-point insertions and the dressed 4-point insertions. Diagrams with such restrictions can all be counted exactly. This results in various critical lines in the ?- g plane, where ? and g are effective zero-dimensional coupling constants. These lines can be localized exactly.
Hooke, orbital motion, and Newton's Principia
NASA Astrophysics Data System (ADS)
Nauenberg, Michael
1994-04-01
A detailed analysis is given of a 1685 graphical construction by Robert Hooke for the polygonal path of a body moving in a periodically pulsed radial field of force. In this example the force varies linearly with the distance from the center. Hooke's method is based directly on his original idea from the mid-1660s that the orbital motion of a planet is determined by compounding its tangential velocity with a radial velocity impressed by the gravitational attraction of the sun at the center. This hypothesis corresponds to the second law of motion, as formulated two decades later by Newton, and its geometrical implementation constitutes the cornerstone of Newton's Principia. Hooke's diagram represents the first known accurate graphical evaluation of an orbit in a central field of force, and it gives evidence that he demonstrated that his resulting discrete orbit is an approximate ellipse centered at the origin of the field of force. A comparable calculation to obtain orbits for an inverse square force, which Hooke had conjectured to be the gravitational force, has not been found among his unpublished papers. Such a calculation is carried out here numerically with the Newton-Hooke geometrical construction. It is shown that for orbits of comparable or larger eccentricity than Hooke's example, a graphical approach runs into convergence difficulties due to the singularity of the gravitational force at the origin. This may help resolve the long-standing mystery why Hooke never published his controversial claim that he had demonstrated that an attractive force, which is ``...in a duplicate proportion to the Distance from the Center Reciprocall...'' implies elliptic orbits.
Orbital Debris Engineering Model (ORDEM) v.3
NASA Technical Reports Server (NTRS)
Matney, Mark; Krisko, Paula; Xu, Yu-Lin; Horstman, Matthew
2013-01-01
A model of the manmade orbital debris environment is required by spacecraft designers, mission planners, and others in order to understand and mitigate the effects of the environment on their spacecraft or systems. A manmade environment is dynamic, and can be altered significantly by intent (e.g., the Chinese anti-satellite weapon test of January 2007) or accident (e.g., the collision of Iridium 33 and Cosmos 2251 spacecraft in February 2009). Engineering models are used to portray the manmade debris environment in Earth orbit. The availability of new sensor and in situ data, the re-analysis of older data, and the development of new analytical and statistical techniques has enabled the construction of this more comprehensive and sophisticated model. The primary output of this model is the flux [#debris/area/time] as a function of debris size and year. ORDEM may be operated in spacecraft mode or telescope mode. In the former case, an analyst defines an orbit for a spacecraft and "flies" the spacecraft through the orbital debris environment. In the latter case, an analyst defines a ground-based sensor (telescope or radar) in terms of latitude, azimuth, and elevation, and the model provides the number of orbital debris traversing the sensor's field of view. An upgraded graphical user interface (GUI) is integrated with the software. This upgraded GUI uses project-oriented organization and provides the user with graphical representations of numerous output data products. These range from the conventional flux as a function of debris size for chosen analysis orbits (or views), for example, to the more complex color-contoured two-dimensional (2D) directional flux diagrams in local spacecraft elevation and azimuth.
The phase diagram of solid hydrogen at high pressure: A challenge for first principles calculations
NASA Astrophysics Data System (ADS)
Azadi, Sam; Foulkes, Matthew
2015-03-01
We present comprehensive results for the high-pressure phase diagram of solid hydrogen. We focus on the energetically most favorable molecular and atomic crystal structures. To obtain the ground-state static enthalpy and phase diagram, we use semi-local and hybrid density functional theory (DFT) as well as diffusion quantum Monte Carlo (DMC) methods. The closure of the band gap with increasing pressure is investigated utilizing quasi-particle many-body calculations within the GW approximation. The dynamical phase diagram is calculated by adding proton zero-point energies (ZPE) to static enthalpies. Density functional perturbation theory is employed to calculate the proton ZPE and the infra-red and Raman spectra. Our results clearly demonstrate the failure of DFT-based methods to provide an accurate static phase diagram, especially when comparing insulating and metallic phases. Our dynamical phase diagram obtained using fully many-body DMC calculations shows that the molecular-to-atomic phase transition happens at the experimentally accessible pressure of 374 GPa. We claim that going beyond mean-field schemes to obtain derivatives of the total energy and optimize crystal structures at the many-body level is crucial. This work was supported by the UK engineering and physics science research council under Grant EP/I030190/1, and made use of computing facilities provided by HECTOR, and by the Imperial College London high performance computing centre.
Spin-orbit coupling of spin-frustrated systems
NASA Astrophysics Data System (ADS)
Takeda, R.; Yamanaka, S.; Yamaguchi, K.
We have investigated the effects of spin-orbit (SO) interactions on noncollinear molecular magnetism by combining the classical Dzyaloshinsky-Moriya (DM) model and ab initio generalized spin orbital (GSO) method. We have derived an estimation scheme of the magnetic anisotropy energy (MAE) and the Dzyaloshinsky vector based on the SO first-order perturbation theory (SOPT1) for GSO Hartree-Fock (GHF) solutions. We found that the fundamental results of GHF-SOPT1 method can be reproduced by diagonalizing the core Hamiltonian plus SO terms, and that the spin topologies of odd-ring systems can be determined by the topological indices of the singly occupied molecular orbitals.
High Harmonic Generation from Multiple Orbitals in N2
McFarland, B.; Farrell, Joseph P.; Bucksbaum, Philip H.; Guehr, Markus; /SLAC, Pulse /Stanford U., Phys. Dept.
2009-03-05
Molecular electronic states energetically below the highest occupied molecular orbital (HOMO) should contribute to laser-driven high harmonic generation (HHG), but this behavior has not been observed previously. Our measurements of the HHG spectrum of N{sub 2} molecules aligned perpendicular to the laser polarization showed a maximum at the rotational half-revival. This feature indicates the influence of electrons occupying the orbital just below the N{sub 2} HOMO, referred to as the HOMO-1. Such observations of lower-lying orbitals are essential to understanding subfemtosecond/subangstrom electronic motion in laser-excited molecules.
Wright, Jason T; Marcy, Geoffrey W; Han, Eunkyu; Feng, Ying; Johnson, John Asher; Howard, Andrew W; Valenti, Jeff A; Anderson, Jay; Piskunov, Nikolai
2010-01-01
We present a database of well determined orbital parameters of exoplanets. This database comprises spectroscopic orbital elements measured for 421 planets orbiting 357 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form on the Web at http://exoplanets.org through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanets Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the selection different biase...
NASA Technical Reports Server (NTRS)
Jordan, J. F.; Boggs, D. H.; Born, G. H.; Christensen, E. J.; Ferrari, A. J.; Green, D. W.; Hylkema, R. K.; Mohan, S. N.; Reinbold, S. J.; Sievers, G. L.
1973-01-01
A historic account of the activities of the Satellite OD Group during the MM'71 mission is given along with an assessment of the accuracy of the determined orbit of the Mariner 9 spacecraft. Preflight study results are reviewed, and the major error sources described. Tracking and data fitting strategy actually used in the real time operations is itemized, and Deep Space Network data available for orbit fitting during the mission and the auxiliary information used by the navigation team are described. A detailed orbit fitting history of the first four revolutions of the satellite orbit of Mariner 9 is presented, with emphasis on the convergence problems and the delivered solution for the first orbit trim maneuver. Also included are a solution accuracy summary, the history of the spacecraft orbit osculating elements, the results of verifying the radio solutions with TV imaging data, and a summary of the normal points generated for the relativity experiment.
Recognition of hand drawn chemical diagrams
Ouyang, Tom Yu
2007-01-01
Chemists often use hand-drawn structural diagrams to capture and communicate ideas about organic compounds. However, the software available today for specifying these structures to a computer relies on a traditional mouse ...
Sketch recognition for Course of Action diagrams
Stolt, Kevin (Kevin E.)
2007-01-01
This thesis describes a software program that recognizes hand-drawn Course of Action diagrams. User input is through sketching, or a combination of sketching and speech. Course of Action symbols are recognized incrementally, ...
DIAGRAM REWRITING AND OPERADS Yves Lafont
Lafont, Yves
DIAGRAM REWRITING AND OPERADS by Yves Lafont Abstract. -- We give a survey of a diagrammatic syntax by generators and relations, PRO, PROP, Schur functor, tangle. #12;2 YVES LAFONT In order to define a PRO, since
Voronoi diagram generation on the ellipsoidal earth
NASA Astrophysics Data System (ADS)
Hu, Hai; Liu, XiaoHang; Hu, Peng
2014-12-01
Voronoi diagram on the earth surface is a powerful tool to study spatial proximity at continental or global scale. However, its computation remains challenging because geospatial features have complex shapes. This paper presents a raster-based algorithm to generate Voronoi diagrams on earth's surface. The algorithm approximates the exact point-to-point geographical distances using the cell-to-cell geographical distances calculated by a geographical distance transform. The result is a distance image on which Voronoi diagram is delineated. Compared to existing methods, the proposed algorithm calculates geographical distances based on an earth ellipsoid and allows Voronoi generators to take complex shapes. Most importantly, its approximation error is bounded thus enabling users to control the accuracy of the Voronoi diagram through grid resolution.
A Smart Thermal Block Diagram Tool
NASA Technical Reports Server (NTRS)
Tsuyuki, Glenn; Miyake, Robert; Dodge, Kyle
2008-01-01
The presentation describes a Smart Thermal Block Diagram Tool. It is used by JPL's Team X in studying missions during the Pre-Phase A. It helps generate cost and mass estimates using proprietary data bases.