the parameters for a polarizable force field from ab initio quantum-chemical calculations, and a rigorous method initio quantum- chemical calculations have become an increasingly impor- tant source of fitting dataParametrizing a polarizable force field from ab initio data. ...

... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... COMPENDIUM OF AB INITIO CALCULATIONS ...

... 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. ...

piezoelectric parts. The spontaneous part is modeled with an ab initio result of a theoretical calculation, while the piezoelectric ...

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 ...

Ab Initio calculations for defects and impurities in elemental and compound semiconductors Characterization of defects and impurities in compound semiconductors Modeling of...

... For example, ab initio quantum chemical calculations when combined with reaction rate theory and kinetics modeling can, in principle, be capable ...

... derivatives (first and second) calculated by ab initio quantum chemical techniques (Maple, Dinur, and Hagler 1988; Hagler et al. ...

Mar 1, 2011 ... Conformational Characteristics of Poly(tetrafluoroethylene) (PTFE) Based Upon Ab Initio Electronic Structure Calculations on Model Molecules ...

... Abstract : The results of ab initio calculations based on the density-functional method and using the norm-conserving pseudopotentials for the ...

... fuels requires an interdisciplinary approach involving ab initio modeling, synthesis ... value of high speed video and quantum chemical calculations to ...

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 ...

In this paper we review the existing theoretical literature on hydrogen storage in single-walled carbon nanotubes. The importance of theoretical simulations for understanding the adsorption procedure and for improving the storage capacity of these nano-materials is underlined. We report two different categories of theoretical approach used for this purpose, i.e. classical ...

Polynomial expressions for the elastic tensor coefficients, the bulk, the shear and Young�s moduli, the speed of sound for longitudinal and transverse waves, the equation of state and the x coordinate of the sulfur atom in pyrite are reported based on ab initio calculations in the range of 0-135 GPa. Comparison with published ...

Ab-initio Calculations to Model Anomalous Fluorine Behavior Milan Diebel1 and Scott T. Dunham2 1 Engineering, University of Washington, Seattle, WA 98195-2500, USA ABSTRACT Implanted fluorine has been motivated to understand the behavior of implanted fluorine in silicon by experiments which suggest

We perform ab initio molecular dynamics simulations to study the dissociation of NaCl in water. The potential of mean force (PMF) between the two ions is determined using the constrained-force method. The simulation windows corresponding to the contact and solvent-separated minima, and the transition state in between, are further analyzed to determine the ...

Ab initio electronic-structure calculations are combined with empirical bond-additivity corrections to yield thermochemical properties of gas-phase molecules. A self-consistent set of heats of formation for molecules in the Si-H, Si-H-Cl, Si-H-F, Si-N-H a...

. The previous ab initio results on lattices of K atoms for coordination numbers z 8, 4, and 2 are analyzed these DFT results for K into contact with a simple and physically appealing quantum-chemical model proposed conclusions are given at the end of the paper. II. THEORETICAL METHOD We have performed the ab ...

The ab initio no-core shell model (NCSM) is extended to include a realistic three-body interaction in calculations for p-shell nuclei. They present results of first applications using the Argonne V8' nucleon-nucleon (NN) potential and the Tucson-Melbourne...

The GaAs(100) surface is modeled by using atomic clusters in order to study the effects of passivation with sulfur. Both the Ga- and the As-terminated surfaces are tied off with S atoms in a 2 {times} 1 reconstruction. The most stable structure is established on the basis of ab initio Hartree-Fock calculations. It ...

The electron transfer (ET) properties of 10- and 12-vertex carboranes are investigated by the ab initio Hartree-Fock method within the Marcus-Hush (MH) two-state model and the Koopman theorem (KT) approach. The calculated value of the ET coupling matrix e...

Ab initio molecular dynamics is used to compute the thermal conductivity of hydrogen at 80 g cm{sup -3} and temperature up to 800 eV. Pressures and ionic structure are compared with orbital-free calculations. Thermal conductivity is evaluated using the Kubo-Greenwood formula and is compared with models currently ...

... Ab initio Energies Calculated Using 3 ... of the Transition States (TS ... Descriptors : *TRANSITIONS, *MOLECULES, COMPUTATIONS, COMPARISON ...

... We carried out ab-initio quantum chemical calculations on these energetic cyclic ethers and generated the electrostatic molecular potential contour ...

... Title : Ab Initio Calculation of Vibrational Circular Dichroism Spectra Using Accurate Post-Self-Consistent-Field Force Fields: trans-2,3 ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Ab Initio Calculation of Intermolecular ...

A calculation was made of the time dependent charge state of a heavy projectile traversing a finite-temperature target. The calculation uses an average-atom model to integrate the rate equations.

We present a calculation of the time dependent charge state of a heavy projectile traversing a finite temperature target. The calculation uses an average-atom model to integrate the rate equations.

A calculation was made of the time dependent charge state of a heavy projectile traversing a finite-temperature target. The calculation uses an average-atom model to integrate the rate equations. (ERA citation 07:045387)

An analysis of the vibrational spectra of the bent triatomic molecules HCO and DCO has been performed using algebraic methods. A model based on coupled U(2) algebras has been proposed for the description of the vibrational spectrum of HCO. The vibron model, based on the U(4) Lie algebras, has then been applied for the calculation of ...

We describe an implementation of the benchmark ab initio electronic structure full configuration interaction model on the Intel Touchstone Delta. Its performance is demonstrated with several calculations, the largest of which (95 million configurations, 4...

... Abstract : Results are presented from ab initio quantum chemical calculations on the ground state potential energy surface for the open shell ...

The ab initio/classical free energy perturbation (ABC-FEP) method proposed previously by Wood et al. [J. Chem. Phys. 110, 1329 (1999)] uses classical simulations to calculate solvation free energies within an empirical potential model, then applies free energy perturbation theory to determine the effect of changing ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... of Molecular Modelling and Ab initio Molecular ...

A model for the evolution of conduction and valence bands of IIIA-VA (InAs, GaAs, and InP) semiconductors under (001) biaxial strain is developed. The model is based on the ab initio calculations which take into account finite strain dependent relaxation of the reference levels. The results of ...

The Cytochrome P450 superfamily of enzymes are of great interest in pharmacology as they participate in an enormous range of physiological processes including drug deactivation and xenobiotic detoxification. We apply ab initio electronic structure calculations to model the interactions of the haem molecule at the ...

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) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ...

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) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ...

Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point

... The first approximation that is generally incorporated into the Schroedinger Theory is known as the Born Oppenheimer Approximation. ...

In this work we show how the ab initio determination of van der Waals coefficients within time-dependent density functional theory can be used to build efficient and accurate atomistic models that describe the long-range interactions of proteins with other proteins and of proteins with semi-conducting surfaces. The ...

We demonstrate the existence of multiple converging sequences in the ab initio no-core shell model. By examining the underlying theory of effective operators, we expose the physical foundations for the alternative pathways to convergence. This leads us to propose a revised strategy for evaluating effective interactions for A-body ...

Ab initio (MP2/6-31G**//MP2/3-21G) calculations yield a value of about 729 kJ/ mole, ... Quantum chemical; Lubricants; Modelling; Semiempirical; Lubrication; ...

The (MNDO) Modified Neglect of Differential Overlap, method is now established as a practical procedure for studying chemical behavior, giving results comparable with those from good ab initio models while requiring less than one-thousandth as much comput...

We present pair potentials for fluorinated methanes and their dimers with CO2 based on ab initio potential energy surfaces. These potentials reproduce the experimental second virial coefficients of the pure fluorinated methanes and their mixtures with CO2 without adjustment. Ab initio ...

The potential energy surface for trimers of hydrogen fluoride is examined for multiple arrangements of the three-molecule cluster. Several established approaches to model the potential energy are examined, including a strictly pairwise additive potential, an established polarizable potential model, another, strictly three-body polarizable ...

We regularize the potential distribution framework to calculate the excess free energy of liquid water simulated with the BLYP-D density functional. Assuming classical statistical mechanical simulations at 350 K model the liquid at 298 K, the calculated free energy is found in fair agreement with experiments, but the excess internal ...

The photoelectron spectra of the weakly bound KrO- anion are simulated using a theory which combines the atoms-in-molecule model for molecular electronic wave functions and the Rau-Fano model for photodetachment intensities [J. Chem. Phys. 112, 5852 (2000)]. The nonrelativistic potential energy curves of the anion are obtained from ab ...

We present a combined computational and experimental study on structural and electric properties of recently synthesized heteroaromatic dyes and their simple aggregates. Ab initio and density functional theory calculations are carried out to investigate ground state and excited state properties along with their modulation induced by ...

Ab initio electronic-structure calculations are combined with empirical bond-additivity corrections to yield thermochemical properties of gas-phase molecules. A self-consistent set of heats of formation for molecules in the Si-H, Si-H-Cl, Si-H-F, Si-N-H and Si-N-H-F systems is presented, along with preliminary values for some Si-O-C-H ...

We present a direct ab initio dynamics study on the kinetics of the hydrogen exchange of methane with a zeolite model. Dynamical calculations are based on the canonical variational transition state theory plus multidimensional semiclassical tunneling corrections. The reaction path information needed for rate ...

An ab initio calculation of a secondary isotope effect on a bond length has been carried out for the first time. Single determinant molecular orbital computations indicate that the mean C--C bond length at 0 degreeK is longer in C$sub 2$H$sub 6$ than in C$sub 2$D$sub 6$ by 0.0015 A. A comparison with model ...

Ab initio theoretical investigations of the dynamics and thermodynamics of a compressed Ne crystal performed using a model that explicitly takes account of the deformation of the electronic shells in the dipole approximation are presented. A dynamical matrix based on a non-empirical short-range repulsive potential and integration over ...

Almost all the ab inito studies performed so far for various (possible) Earth's inner core materials were conducted by comparing together the computed longitudinal (Vp) and shear (Vs) wave velocities to the first- order velocity term of seismological models. We here demonstrate that further constraints on the Earth's inner core composition can be provided if first-principles ...

Owing to their small mass, hydrogen atoms exhibit strong quantum behavior even at room temperature. Including these effects in first-principles calculations is challenging because of the huge computational effort required by conventional techniques. Here we present the first ab initio application of a recently developed stochastic ...

Combined ab initio and micromagnetic simulations are carried out to build up a direct relationship between critical switching current Jc and geometric structure (in-plane lattice constant a and film thickness) of FePt in magnetic tunnel junctions. Ab initio calculations predict that the strain ...

We present the result of ab initio modeling of the Ge(111)-(2 � 1) surface electronic structure in the presence of donor doping atom at certain position in the surface bilayer of (2 � 1) reconstruction. We briefly compare these results with the data of experimental low temperature STM investigations. Ab ...

The production of OH and HO(2) in Cl-initiated oxidation of cyclohexane has been measured using pulsed-laser photolytic initiation and continuous-laser absorption detection. The experimental data are modeled by master equation calculations that employ new G2(MP2)-like ab initio characterizations of important ...

We present full-dimensional potential energy surfaces (PESs) for hydrated chloride based on the sum of ab initio (H(2)O)Cl(-), (H(2)O)(2), and (H(2)O)(3) potentials. The PESs are shown to predict minima and corresponding harmonic frequencies accurately on the basis of comparisons with previous and new ab initio ...

Ab initio MO/MP4, SD-CI, and CCD models were invoked in the consideration of carbon dioxide and ethene insertion into Cu(II)-R bonds. For R = H, CH{sub 3}, and OH, the authors calculated the activation energy and reaction enthalpy for these reactions and presents the related arguments here.

The authors present a newly developed, ab-initio, self-consistent procedure for predictive calculations of electronic and related properties of ferroelectric materials. Known as the Bagayoko, Zhao, and Williams (BZW) procedure, this approach resolves the long-standing disagreement between experimental and theoretical conduction bands, in general, and band ...

Experimental single-molecule stretching curves for three backbone architectures (single-stranded DNA, various types of peptides, polyvinylamine) are quantitatively compared with corresponding quantum-chemical (zero-temperature) ab-initio calculations in the high-force range of up to two nanonewtons. For high forces, quantitative agreement is obtained with ...

Electronically nonadiabatic effects during the chemisorption of hydrogen atoms on an Al(111) surface are simulated ab initio using time-dependent density-functional theory for the electrons in combination with Ehrenfest dynamics for the nuclei. Strongly nonadiabatic effects close to the spin transition of the H atom are identified, and the dissipated ...

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 challenging task to extend ...

We describe large scale ab initio quantum chemical and mixed quantum mechanics/molecular mechanics (QM/MM) methods for studying enzymatic reactions. First, technical aspects of the methodology are reviewed, including the hybrid density functional theory (DFT) methods that are typically employed for the QM aspect of the calculations, ...

We present an application of the bond additivity model to structural units of typical glass-forming materials with the use of ab initio molecular orbital theory. In order to estimate the refractive indices and third-order nonlinear optical susceptibilities of these materials, bond and reduced polarizabilities of the small cluster ...

The number of ab initio molecular electronic calculations has increased dramatically in the last few years. Both the practitioners and other interested students of the results of the calculations have found it increasingly difficult to determine the prese...

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...

The authors have performed ab initio quantum mechanical calculations in monomeric clusters modeling the 12 different T sites of zeolite ZSM-5. By comparing the results of calculations that use minimum basis sets with those that employ valence double-[zeta] bases, the authors conclude that ...

We describe the construction of a multi-phase equation of state for carbon at extreme pressures based on ab initio electronic structure calculations of two solid phases (diamond and BC8) and the liquid. Solid-phase free energies are built from knowledge of the cold curves and phonon calculations, together with ...

We have carried out ab initio electronic structure calculations of the spin-orbit and rotation-orbit

The chemical structure and bonding of the hypermetallic Al5C and Al5C- species have been studied by photoelectron spectroscopy and ab initio calculations.

Ab initio molecular orbital calculations on phosphites, protonated phosphites, and protonated phosphates reveal important stereoelectronic effects. In the phosphites, an antiperiplanar lone pair on oxygen to the phosphite lone pair raises the energy of th...

Ab initio calculations are carried out to determine ?? (true), the first-order contribution to the spin-rotation constant, ??, for the X2? ground states of ...

Formalisms suitable for calculating the rate of electron exchange between transition metal complexes in aqueous solution are reviewed and implemented in conjunction with ab initio quantum chemical calculations which provide crucial off-diagonal Hamiltonia...

Ab initio calculations of single and double differential cross sections for ionization by fast, charged particles within the framework of Born approximation are presented. In addition, a semiempirical method based on the asymptotic Bethe-Boron expansion i...

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...

Hensley, J.M., S. Green, and G.W. Flynn, 1991: A simple ab initio calculation for energy transfer in collisions of hot hydrogen atoms with carbon dioxide. ...

With blooming experimental synthesis of various nanostructures out of many semiconductor materials, there is an urgent need to calculate the electronic structures and optical properties of these nanosystems based on reliable ab initio methods. Unfortunately, due to the O(N^3) scaling of the conventional ab ...

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 ...

... goals of this program have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...

Metal atom clusters are studied based on the application of ab initio quantum mechanical approaches.

... Molecular Orbital Studies on Nucleoside Antibodies VIII, Ab Initio Calculation of Cubic Force Constants in Formamide Monomer, Formamide Dimer ...

... Concomitantly, we calculated the fundamental interactions of fluorine atoms with silicon using ab initio quantum mechanics, in order to understand ...

... Corporate Author : NATIONAL STANDARD REFERENCE DATA SYSTEM. ... observable properties including the total energy, dissociation energy ...

We have carried out extensive high quality ab initio electronic structure calculations of the ground

We report on the determination of a high quality ab initiu potential energy surface (PES) and dipole