... Title : Chalcopyrite Magnetic Semiconductors: An Ab-Initio Study of Their Structural, Electronic and Magnetic Properties. ...
DTIC Science & Technology
... Ab initio study on atomic structures and physical properties of CdSe quantum nanodots ... Figure 2. Diagram of covered nanodots. ...
... Title : Ab Initio Study on Atomic Structures and Physical Properties of CdSe Quantum Nanodots. Descriptive Note : Final rept. ...
... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : Ab Initio Study of the Structure ...
... Title : Structure of Perfluoromethanimine by Microwave, Infrared, and Raman Spectroscopy, Electron Diffraction, and ab Initio Methods,. ...
... nightmares for traditional quantum chemical approaches for optimizing structures of such ... an unbiased manner with ab initio forces. ...
Ab initio electronic structure methods can supplement CALPHAD in two major ways for subsequent applications to stability in complex alloys. The first one is rather immediate and concerns the direct input of ab initio energetics in CALPHAD databases. The o...
National Technical Information Service (NTIS)
Ab initio electronic structure methods can supplement CALPHAD in two major ways for subsequent applications to stability in complex alloys. The first one is rather immediate and concerns the direct input of ab initio energetics in CALPHAD databases. The other way, more involved, is the ...
DOE Information Bridge
The detailed molecular structure of methyl phosphonate, the simplest phosphorus ester, was determined by ab initio quantum-chemical calculations in a variety of basis sets. Computed properties include the optimized structure, dipole moment, number and rel...
The chemical structure and bonding of the hypermetallic Al5C and Al5C- species have been studied by photoelectron spectroscopy and ab initio calculations.
Energy Citations Database
Examples of transition metal complexes containing dihydrogen ligands are investigated using ab initio electronic structure calculations employing effective core potentials. Calculated geometrical structures and relative energies of various forms of WL(sub...
Metal atom clusters are studied based on the application of ab initio quantum mechanical approaches.
NASA Technical Reports Server (NTRS)
... goals of this program have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...
We have carried out extensive high quality ab initio electronic structure calculations of the ground
The equilibrium structure, dipole moment, harmonic vibrational frequencies, and infrared intensities
... the potential energy surface provided by modern electronic structure ... screening approach, to determine the equilibrium geometry and composition ...
... system organized around a common data structure. ... molecular structures; optimize structures using molecul ... ab initio quantum chemical tech- niques ...
Quantum mechanical-based (or ab initio) methods are used to predict the stability properties of materials although their application is limited to relatively simple systems in terms of structures and number of alloy components. However thermodynamics of c...
We have carried out ab initio electronic structure calculations of the spin-orbit and rotation-orbit
Ab initio quantum chemical techniques are used to investigate covalently-bonded and hydrogen-bonded species that may be important intermediates in the reaction of hydroxyl and hydroperoxyl radicals. Stable structures of both types are identified. Basis se...
General procedures for computing alloy phase equilibria from ab initio electronic structure calculations are reviewed and applied to the Al-Li phase diagram. Free energies were calculated by the cluster variation method (CVM) in the tetrahedron approximat...
A global search for possible LiF cluster structures is performed up to (LiF)(8). The method is based on simulated annealing, where all the energies are evaluated on the ab initio level. In addition, the threshold algorithm is employed to determine the energy barriers for the transitions among these structures, for ...
PubMed
Structural and thermal properties of small lithium clusters are studied using ab initio-based Monte Carlo simulations. The ab initio scheme uses a Hartree-Fock/density functional treatment of the electronic structure combined with a jump-walking Monte Car...
We have studied structural and dynamical properties of Mg2Sn by employing an ab-initio pseudopotential method and a linear response scheme, within the generalised gradient approximation. The calculated lattice constant, bulk modulus and pressure derivative of bulk modulus are in agreement with previous ab-initio calculations and ...
NASA Astrophysics Data System (ADS)
The goal of this research is to provide increased understanding of the chemistry and reactivity of pentavalent phosphorus compounds by analysis of structures and electronic structures obtained from ab initio molecular orbital calculations. Electronic stru...
SnO2: BULK AND SURFACE SIMULATIONS BY AN AB INITIO NUMERICAL LOCAL ORBITALS METHOD A.V. POSTNIKOVa structure of ideal bulk SnO2 is well studied by ab initio calculations (Peltzer y Blanc�a, Svane study of several SnO2 surfaces, com- paring their energies of formation, and started to look
E-print Network
The nuclear magnetic resonance chemical shift is one of the most powerful properties available for structure determination at the molecular level. A review of advances made in the ab initio calculation of chemical shielding during the past five years is presented. Specifically, progress in the areas including the effects of an unpaired ...
There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) predicts low-lying levels in p-shell nuclei. It is a chall...
We present an algorithm for calculating the conformational thermodynamics of large, flexible molecules that combines ab initio electronic structure theory calculations with a torsional path integral Monte Carlo (TPIMC) simulation. The new algorithm overcomes the previous limitations of the TPIMC method by including the thermodynamic ...
NMR chemical shifts for an L-alanine molecular crystal are calculated using ab initio plane wave density functional theory. Dynamical effects including anharmonicity may be included by averaging chemical shifts over an ensemble of structural configurations generated using molecular dynamics (MD). The time scales required mean that ...
Dec 8, 2009 ... We examine different molecular structures of nitrogen based on recent observations for analog systems. A structure with Immm symmetry and ...
NASA Website
... goals of this program have been to develop new, more effective methods for perform in accurate ab initio electronic structure calculations and to ...
... Abstract : The objectives of this work which were fulfilled were to (1) use high level ab initio molecular orbital theory to predict the structures and ...
... known GAMESS suite of computer codes [2]. Accurate ab initio methods pro- ... to the systematic improvement of standard quantum-chemical methods ...
... This allowed her to gain insight into SiGe alloy superlattice structures, etching of Si by fluorine, the rate limiting chemical vapor deposition process ...
Research progress on an alternative method to ab initio variational and perturbative approaches for the electronic structure of molecules is described. Progress in the report year on the evaluation of (1) molecular properties, (2) energy derivatives with ...
In the present work we shall discuss recent advances in quantum chemical methodology that have improved the reliability of ab initio electronic structure ...
Results are reported from SDCI and CPF ab initio computations for the ground and low-lying states of
... crystal structures which are ordered superstructures of a parent disordered phase; a highly reliable statistical mechanical method (CVM) has now ...
... substantial impact; these tools are now incorporated in many ab initio codes ... Most commonly used quantum chemical methods possess one or the ...
on "Quantum Chemical Calculation of the Equilibrium Structures of Small ... based on the application of ab initio quantum mechanical approaches. This ...
powder XRD for fine particle analysis, and single crystal. XRD for coarse materials analysis and ab-initio structure determination. Hybrid-XRD design will ...
... profiles and three-dimensional quantitative structure-activity relationship pharmacophores using ab initio quantum chemical and pharmacophore ...
(either ab initio methods or basis sets) for electronic structure calculations, and a graph theory procedure for identifying instantaneous molecular fragment identities...
Science.gov Websites
... softening of Al-based fcc alloys using ab initio Korringa-Kohn-Rostoker augmented-spherical-wave electronic structure calculations is discussed. ...
... Beta-(1-methyl-2-pyridinium) - alpha-cyano-4-styryldicyanomethanide was optimized using semi-empirical and ab initio quantum chemical methods ...
... previous grant period have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...
... progress is reported in development of ab initio computational methods for the electronic structures of molecules employing atomic spectral-product ...
... calculations have been performed on the weakly bonded CO-02 complex at the ... In the T-shaped structure, the oxygen is very weakly bonded to the ...
... optimized. Then, with the C4 C6 twist angle still constrained to 00, ... structure on the rotational pathway, yielding a rotational barrier ...
For some simple, but nontrivial molecular systems, the interaction potentials are now well determined from ab initio electronic structure calculations ...
... a transition metal, A is mostly a IIIA or IVA element of periodic table, and X ... the M2AlC formula to address the influence of the M elements (Y, Zr ...
... More recently, extensive calculations on the nitrogen oxides were conducted employing the density functional method (ref 2) in conjunction with a ...
The reaction of some organophosphorus compounds with cholinesterase is thought to proceed by nucleophilic substitution through a pentacoordinate trigonal bypyramidal structure. Recently, Robert Holmes suggested that a hexacoordinate species might be invol...
... The structures of the entrance channel transition states show the four-body intermediates ... Campus Box 427 Boulder, CO 80309-0427 ...
... Abstract : Electronic structure calculations using theoretical methods based on the linked-diagram theorem are reported for a series of dissociation ...
Mar 1, 2011 ... Conformational Characteristics of Poly(tetrafluoroethylene) (PTFE) Based Upon Ab Initio Electronic Structure Calculations on Model Molecules ...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
In this work we discuss the summation of the Parquet class of diagrams within Green�s function theory as a possible framework for ab initio nuclear structure calculations. The theory is presented and some numerical details are discussed, in particular the approximations employed. We apply the Parquet method to a simple model, and ...
In this work, we present a study on water acetonitrile (AN) mixtures by molecular dynamics ab initio and X-ray diffraction techniques. Comparison of the experimental total G(r) functions of the mixtures with the results of molecular dynamics simulation shows an overall good agreement. The properties of hydrogen bonded clusters (water clusters, and water AN ...
We have investigated the electronic structure of TTF-TCNQ under uniaxial compression with ab initio plane-wave pseudopotential calculations within the local-density approximation and generalized gradient approximation. Depending on the compression direction, the constituent molecules are deformed in different ways. Along with these ...
An ab initio quantum-chemical study has been made of the possible existence in terms of structural and thermodynamic stabilities of the pentacoordinated nitrogen hydrides and fluorides, NF(n)H(5-n) for n=0 to 5. Three structurally stable species have been...
Quantum mechanical-based (or ab initio) methods are used to predict the stability properties of materials although their application is limited to relatively simple systems in terms of structures and number of alloy components. However thermodynamics of complex multi-component alloys requires a more versatile approach afforded within ...
Research completed during the period 1 Feb. 1990 - 28 Feb. 1994 is summarized in the following included papers: 'Ab Initio Statistical Mechanics of Structural Phase Transition'; 'Ab Initio Molecular Dynamics: Analytically Continued Energy Functionals and Insights into Iterative Solutions'; ...
We present results for the static and dynamic structural properties of undercooled liquid Si, at several temperatures between 1550 K and 1100 K, obtained through orbital-free ab-initio molecular dynamics simulations. The local bond angle distributions show a modest increase in the tetrahedral order upon decreasing the temperature. We also analyze the ...
Structural and energetic properties of small, deceptively simple anionic clusters of lithium, Lin-, n = 3-7, were determined using a combination of anion photoelectron spectroscopy and ab initio calculations. The most stable isomers of each of these anions, the ones most likely to contribute to the photoelectron spectra, were found ...
The generalized two-dimensional Peierls-Nabarro (PN) model7 for studying interfaces is developed further, where an exact generalized stacking fault energy ?-surface obtained from ab initio calculations acts as an input function for the generalized PN model. Using the multiscale modeling techniques, which combines elastic theory with ab ...
The lowest two ab initio potential energy surfaces (PES), and the corresponding nonadiabatic couplings between them, have been obtained for the H{sub 3}{sup +} system; the molecular data are compared to those calculated with the diatomic in molecules (DIM) method. The form of the couplings is discussed in terms of the topology of the molecular ...
Structural and energetic properties of small, deceptively simple anionic clusters of lithium, Li(n)(-), n = 3-7, were determined using a combination of anion photoelectron spectroscopy and ab initio calculations. The most stable isomers of each of these anions, the ones most likely to contribute to the photoelectron spectra, were found ...
The high-pressure induced phase transformation from the zinc blende to rocksalt structure in SiC has been studied by the ab initio molecular dynamics method. The simulations showed that SiC passes through a tetragonal intermediate state before transforming to a monoclinic phase at 160�GPa. The mechanism for this phase transformation ...
A systematic method for approximating the ab initio electronic energy of crystal lattices has been improved by the incorporation of long range electrostatic and dispersion interactions. The effect of these long range interactions on the optimization of the crystal structure is reported. The harmonic lattice dynamics have been evaluated ...
... from federally funded research, testing and training ... for Research Development Test and Evaluation ... COMPENDIUM OF AB INITIO CALCULATIONS ...
... Accession Number : ADA219907. Title : An Ab Initio Study of the Geometry and Rotational Barrier of 4- Phenylimidazole. ...
... from federally funded research, testing and training ... and agencies for Research Development Test and Evaluation ... Title : Ab Initio Calculations of the ...
... Title : Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields. ...
... Title : AB Initio Quantum Chemical Investigations of Solubilities in Supercritical Solutions. Descriptive Note : Conference Paper,. ...
A combination of high-level ab initio electronic-structure calculations and empirical bond-additivity corrections are used to calculate thermochemical properties of gas-phase molecules. A self-consistent set of heats of formation for molecules in the SiH,...
A combination of high-level ab initio electronic-structure calculations and empirical bond-additivity corrections are used to calculate thermochemical properties of gas-phase molecules. A self-consistent set of heats of formation for molecules in the SiH, Si--H--Cl, Si--H--F, Si--N--H and Si--N--H--F systems is presented.
The results of ab initio multi-configuration self-consistent field (MSCF) calculations on 1,2-cyclohexadiene are reported. These calculations support the contention that the compound's equilibrium geometry is strongly bent and chiral but can easily racemize. Structures are proposed for the ground state, diradical, and ...
- tion was at best able to produce reasonable struc- tures for only very small alpha-helical proteins. Acad. Sci. USA 97(21), 11221�11226. Holm, L., and Sander, C. (1995) Dali: A network tool for proteinFunctional Inferences from Blind ab Initio Protein Structure Predictions Richard Bonneau, Jerry
Electron energy-loss spectroscopy has been shown to be a powerful tool to determine the chemistry and the electronic structure at grain boundaries by analyzing the energy loss near edge structure (ELNES). This paper describes the ability of ab-initio density of state calculations to perform detailed quantitative analysis at interfaces.
Results of ab initio molecular orbital calculations are reported for complexes of eleven anions with a water molecule. Optimized geometries obtained with the 6-31G(d) basis set were used in calculations including diffuse functions and the correlation energy. The present structural and energetic results complement and extend ...
In this work, the structure of symmetric N2O3 was investigated using ab initio methods. Bond lengths and bond angles were determined using the 6-31 G* and the 6-311 G* basis sets using both SCF and MP2 theory. At the highest level of theory considered in ...
The detailed molecular structures including the equilibrium conformations and energies of the four prototype phosphorus compounds exhibiting a phosphorus oxygen phosphorous(P-O-P) interconnection, H4P2O2n-1 for n=1 to 4, were determined by ab initio quant...
The structures of Al sub 2 F sub 7- and Al sub 2 Cl sub 7- have been investigated using ab initio molecular orbital theory including the effects of polarization functions in the basis sets. The Al sub 2 F sub 7- ion has a linear or nearly linear Al-F-Al b...
We present a theoretical investigation of the electronic structure of an InAs monomolecular plane inserted in bulk GaAs. Our calculations are based on the ab initio self-consistent pseudopotential method. Both electrons and holes are found to be strongly ...
The rotational mechanism of the NH{sub 4}{sup +} ion in water is analyzed by using both semiempirical (AM1) and ab initio (6-31G* SCF level) methods. AM1 predicts rapid rotation at any degree of first solvent shell hydration from n = 1-6. These results are considered artifactual since AM1 favors ion-water structures of a type not found ...
For the equilibrium immiscible Fe-Cu system, ab initio calculations using the projector augmented wave method identify the relatively stable structures of the metastable Fe25Cu75 and Fe50Cu50 alloys to be both of fcc and determine their corresponding lattice constants and cohesive energies. Some of the ab ...
... Title : AB Initio Study of the Electronic Magnetic Circular Dichroism ... functions are determined using as initio quantum chemical techniques including ...
