... Abstract : Results are presented from ab initio quantum chemical calculations on the ground state potential energy surface for the open shell ...
DTIC Science & Technology
... Accession Number : ADA351780. Title : Ab Initio and DFT Potential Energy Surfaces for Cyanuric Chloride Reactions. Descriptive Note : Final rept. ...
... Accession Number : ADA270577. Title : Ab Initio Potential Energy Surface for the H + OCS Reaction. Descriptive Note : Final rept. ...
... [2"- ARMY RESEARCH LABORATORY [C Ab Initio Potential Energy Surface for H + OCS Reactions: Extended Basis Sets ...
... We carried out ab-initio quantum chemical calculations on these energetic cyclic ethers and generated the electrostatic molecular potential contour ...
... Results of this study substantiate findings from an earlier quantum chemical study using a lower ... for (I) and (II) based on the earlier ab initio study. ...
... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Ab Initio Calculation of Intermolecular ...
We report on the determination of a high quality ab initiu potential energy surface (PES) and dipole
NASA Technical Reports Server (NTRS)
... eg, SiHl6= has a negative ionization potential. ... V. POTENTIAL ENERGY SURFACES AND DYNAMICS ... initio with effective core potentials, ab initio ...
... agencies for Research Development Test and Evaluation ... Potentials of Mixed Systems: Testing the Lorentz ... Mixing Rules with Ab Initio Calculations. ...
Ab initio quantum chemistry methods are used to study the energetics of interactions of O atoms with
Harding and Goddardl (HGI) computed accurate ab initio potential ... In order to resolve this uncertainty Harding and Goddard ...
NASA Website
We have carried out extensive high quality ab initio electronic structure calculations of the ground
... the potential energy surface provided by modern electronic structure ... screening approach, to determine the equilibrium geometry and composition ...
The predissociation line broadening in the Schumann-Runge bands of O2 is explained by an ab initio calculation of the pertinent repulsive potential energy curves and spin-orbit matrix elements. The ab initio results provide an overall qualitative picture ...
National Technical Information Service (NTIS)
An ab initio model is developed for the potentials in ionic molecular solids in which the electron covalenc within the molecular ions substantially affects the interionic interactions. By treating the intermolecular and intramolecular interactions on the ...
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...
A simple method is described to adjust a potential energy surface to improve agreement with experiment. An application is made to the ab initio HCO potential energy surface.(AIP)
Energy Citations Database
This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and electrostatic molecular potential contour maps for cationic polymerization; Prediction of crystal density;...
with molecular dynamic simulations in combination with high level correlated ab initio quantum chemical the existing minima in the PES. 2. Ab initio quantum-chemical calculations. The lowest energy minima (within surface analysis by metadynamics. Gibbs energies and populations obtained from ab ...
E-print Network
... We have also calculated further ab-initio atom class-atom class potential functions. Keywords: Quantum chemical electrostatic molecular potential ...
The results of an ab initio calculation of the potential energy surface governing atomic hydrogen recombination in the presence of helium atoms are presented. (auth)
... pressure regions where dissociation, ionization, and elec ... different ab initio, DFT, or semiempirical potentials. The reference potential could rely on a ...
A classical Lennard-Jones potential is derived from a fit to the ab initio energies obtained from an all-electron mixed-basis calculation for methane in zeolite LTA. The potential predicts the heat of adsorption, adsorption isotherm, and self-diffusivity of methane in excellent agreement with experiment. This study ...
PubMed
A careful comparison of some properties of systems of helium atoms in the liquid and solid phases is performed for several ab initio two-body potentials from the literature. Additional contributions from a three-body potential are considered as well. The multiweight diffusion Monte Carlo method is employed to ...
The theory of trapping and diffusion of helium and hydrogen in metals is reviewed. The fundamental aspects of the behavior of these particles is emphasized and hence ab initio methods of calculation of interatomic potentials are described. In particular, ...
... furnished keywords include: nitroaromatic; nucleophilic attack; electrostatic potential; nitrobenzene; ab initio self-consistent-field calculations; and ...
... Energetic polymers, Oxetanes, Quantum Chemical calculations, Configuration ... MRD/CI), Energetic compounds, Ab-initio potential functions, Crystal ...
In the present work we shall discuss recent advances in quantum chemical methodology that have improved the reliability of ab initio electronic structure ...
control of molecular dynamics; grid methods in the solution of time-dependent problems in quantum mechanics; ab initio calculation of potential energy surfaces and vibronic...
Science.gov Websites
An approach is developed to enhance sampling for ab initio Monte Carlo and ab initio path integral Monte Carlo calculations of molecular clusters by utilizing an approximate potential as a guide to move in the configuration space more efficiently. The interpolated potential ...
For some simple, but nontrivial molecular systems, the interaction potentials are now well determined from ab initio electronic structure calculations ...
... have potential applications in medicinal drug design as hydrophobic pharmacophores [1 ... 7]. Due to their axially direc- ted terminal bonds and rigid ...
... The structures of the entrance channel transition states show the four-body intermediates ... Campus Box 427 Boulder, CO 80309-0427 ...
The unimolecular decay lifetimes of several vibrational states of HN2 are determined on the basis of
... Title : A Comparative Study of Nonlocal Density Functional Theory and ab initio Methods: The Potential Energy Surface of sym-Triazine Reactions. ...
Using a theoretical quantum chemical approach, we .... completion of the ab initio calculation of the Rydberg and valence potential ...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
The recombination dynamics for the SiH2 +SiH2 = SiH2 reaction are studied by quasiclassical trajectory methods using a global potential-energy surface fitted to the available experimental data and the results of various ab initio calculations. The potenti...
There is reported here an accurate ab initio calculation of the fixed nuclei potential curve for the B prime singlet sigma u state of H2 together with approximate values of the adiabatic corrections to the potential curve for this state. The state is obse...
The potential barriers for the internal rotation of silole dimers are studied theoretically using the ab initio molecular orbital method at the RHF/6-31G** level of calculations. In 2,2{prime}-bisilole, it is found that the anti-conformation is the most stable structure in the ground state and that the potential ...
The comprehensive study of the ab initio pair potentials and prediction of properties for acetonitrile and methanol [J. Chem. Phys. 116, 7627 (2002), preceding paper] is extended to examine the vapor-liquid equilibria of their mixture. An ab initio pair interaction ...
NASA Astrophysics Data System (ADS)
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 simulation of the vapour�liquid phase coexistence of neon and argon using ab initio are reported for the vapour�liquid phase coexistence of neon and argon. For neon two dierent quantum chemical interactions. In addition calculations are also reported for neon using a potential that includes three
The Lorentz-Berthelot mixing rules are extensively used for estimating intermolecular potential parameters between pairs of non-identical molecules (ij) from those between pairs of identical molecules (ii and jj). Ab initio molecular calculations allow di...
Results of ab initio Hartree-Fock calculations are presented for the nine-coordination-shell cluster Be{sub 69}. Binding energy, ionization potential, electrical field gradient, nuclear-electrostatic potential, diamagnetic shielding constant, second moments of charge, and Mulliken populations are reported for ...
Ab initio molecular orbital calculations of various fragments of the DNA backbone have been performed to aid our understanding of charge localization and transfer following DNA irradiation. Koopmans ionization potentials of H[sub 3]PO[sub 4], H[sub 2]PO[sub 4][sup [minus
Results are presented from ab initio quantum chemical calculations on the ground state potential energy surface for the open shell doublet reaction: HNO + NO right arrow N2O + OH. (I) This reaction is thought to be Important in the sustained combustion of...
Accurate quartet- and doublet-state potential-energy surfaces for the interaction of a hydrogen atom and an oxygen molecule in their ground states have been determined from an ab initio calculation using large-basis sets and the internally contracted mult...
Ab initio calculations using extended basis sets are presented for the potential energy surface (PES) of H + OCS. There are two major reaction channels on the PES; Reaction (I) is H(2S) + OCS(1(Sigma)) yields OH(2(Pi)) + CS(1(Sigma)), and Reaction (II) is...
Ab initio SCF-MO calculations were performed to obtain a torsional potential function for the HONO molecule. Calculations were made for the cis and trans conformations with the STO-3G, 4-31G, 6-31G*, 4-31G and 6-31G** basis sets. Complete geometry optimiz...
. In the present context it is particularly the oxygen environment which acts as such a reservoir, because it can oxygen chemical potential. 2.2 Calculating Gibbs free energies As apparent from eqs. (3) and (5 as the chemical potential of the oxygen environment. Since the RTO-EN-AVT-142 2 - 3 Ab Initio Atomistic
A Combined Ab Initio and Bond-Order Potentials Study of Cohesion in Iridium Marc J. Cawkwell1 , Duc and excellent resistance to oxidation and corrosion offered by iridium suggest numerous applications since highlighted iridium as worthy of significant industrial interest and academic study. Owing to its
... Title : Chalcopyrite Magnetic Semiconductors: An Ab-Initio Study of Their Structural, Electronic and Magnetic Properties. ...
... 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,. ...
Both ab initio MO--LCAO--SCF and the electron-gas (or Gordon--Kim) methods have been used to compute the intermolecular potential (Phi) of N/sub 2/ molecules for seven different N/sub 2/--N/sub 2/ orientations. The ab initio calculations were carried out using a (4s3p) contracted Gaussian basis ...
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 ...
The methodology of nonempirical ab initio quantum mechanical calculations is reviewed as applied to the field of mineral surface chemistry and water-rock geochemical kinetics. The ab initio treatment of adsorption deals with the covalent forces between surface atoms and molecules either in solution or in the gas ...
We report a highly correlated multireference configuration interaction calculation of the near-equilibrium potential energy surface of ozone using a large correlation consistent basis set. Three-dimensional analytical expressions are obtained for the potential energy and dipole moment functions using least-squares fits to ab ...
The interaction of CO{sub 2} and water is investigated by a combination of ab initio and SOLDRI-MM2 techniques. Ab initio results at levels of theory as high as MP2/6-311+G**//6-31G** are found to be in reasonable agreement with experiment. The R.{theta} potential energy surfaces generated for ...
The rigorous theory of ion mobilities recently developed by Viehland and Mason is used with experimental mobilities of Li ions in helium gas to test the ab initio interaction potential calculated for this system by Catlow, et al. The Catlow potential repr...
... Title : AB Initio Study of the Electronic Magnetic Circular Dichroism ... functions are determined using as initio quantum chemical techniques including ...
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, ...
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. ...
A practical method of calculating the intrinsic reaction coordinate starting at a saddle point is proposed. The method has been used in combination with the analytical evaluation of the energy gradient for the calculation of the reaction coordinate on an ab initio potential energy surface. The reaction coordinates are obtained for the ...
Molecular orbital calculations on the nickel pentamer cluster were carried out using ab initio methods as well as density functional methods. The molecular orbital cluster approach using effective core potentials (ECP) was used for the ab initio calculati...
Ab-initio study of zone centre phonons in rare-earth hexaborides, MB6, has been made using self-consistent density functional method based on norm-conserving pseudo-potentials and numerical atomic orbitals as basis set. Calculated values of zone centre phonons are in fair agreement with the experimental results.
Dynamical calculations are performed on an ab initio potential energy surface for KCN. Approximate variational solutions of the vibrational Eckart hamiltonian are presented for several states. Fundamental vibrations are found to lie at 302�7 cm-1 and 119�7 cm-1. An effective rotational hamiltonian is solved for several vibrational ...
The potential energy surfaces for the doublet pi and doublet sigma states in the collinear F+HH reaction have been calculated with ab initio restricted Hartree-Fock (GRHF) and GRHF-CI (configuration interaction) methods. The doublet pi state in the CI cal...
Ab initio and nonlocal density functional theory (DFT) calculations were performed to determine reaction mechanisms for formation of the six- membered ring C3N3Cl3 (cyanuric chloride) from the monomer, cyanogen chloride (ClCN). MP2 geometry optimizations ...
Ab initio calculations were performed to investigate reaction mechanisms for formation and decomposition of the six-membered ring C3N3H3, known as sym-triazine. MP2 geometry optimizations with QCISD(T) energy refinements for critical points on the potenti...
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...
Ab Initio electronic structure calculations using analytical energy derivative methods and automated potential energy surface walking techniques have been carried out on the tautomerization reaction path connecting formamide (F) H2N-CHO, through a transit...
Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point
The unimolecular dissociation dynamics of disilane are investigated using classical trajectory methods with a global potential-energy surface fitted to the available experimental data and the results of various ab initio calculations. The potential surfac...
An ab initio SCF computational study of the structural features, relative stabilities and electrostatic potentials of the isomers 1,4- and 1,2-dioxin, and their three isomeric mononitro derivatives is reported. Within each group, the peroxidic systems wer...
We present pair potentials for Cu and Al obtained by using the method of Moebius transform introduced by Chen (Phys. Rev. Lett. 64, 1193 (1990)) to invert the cohesive energy. Calculations of the cohesive energy have been done both in the fcc and bcc stru...
The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determine...
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 initio ...
Empirical many-body potentials of the glue-type have been constructed for the Al-Pb system using the force matching method. The potentials are fitted to experimental data, physical quantities derived from ab initio linear muffin-tin orbitals calculations and a massive quantum mechanical database of atomic forces ...
The framework of ab initio density-functional theory (DFT) has been introduced as a way to provide a seamless connection between the Kohn-Sham (KS) formulation of DFT and wave-function based ab initio approaches [R. J. Bartlett, I. Grabowski, S. Hirata, and S. Ivanov, J. Chem. Phys. 122, 034104 (2005)]. Recently, ...
In this work we present a theoretical and experimental study of the acetylene-hydrogen system. An ab initio potential surface has been obtained by ab initio quantum chemistry methods. This 4-dimensional potential is further used to compute pressure broadening coefficients ...
The lattice constants and cohesive energies of some possible metastable Cu-W compounds are obtained by ab initio calculation and the formation of a metastable phase at Cu75W25 is predicted for the equilibrium immiscible Cu-W system. The prediction is in agreement with the fact that a metastable hcp phase was indeed observed in the Cu75W25 multilayer films ...
A new exchange-Coulomb semiempirical model potential energy surface for the He-N2 interaction has been developed. Together with two recent high-level ab initio potential energy surfaces, it has been tested for the reliability of its predictions of second-virial coefficients and bulk transport phenomena in binary ...
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 ab initio full ...
We have calculated the melting temperature of tungsten by two ab initio approaches. The first approach can be divided into two steps. In the first step, we simulate a large coexisting solid and liquid system by the classical embedded-atom method potential and obtain an approximate melting temperature. In the second step, we compute the ...
An accurate and efficient molecular alignment technique is presented based on first principle electronic structure calculations. This new scheme maximizes quantum similarity matrices in the relative orientation of the molecules and uses Fourier transform techniques for two purposes. First, building up the numerical representation of true ab initio ...
PubMed Central
Potential energy curves for electronic states of Hg/sub 2/ and TlHg are presented and analyzed. They are derived using large scale configuration interaction procedures for the valence electrons, with the core electrons represented by ab initio relativistic effective potentials. The effect of spin-orbit coupling are ...
Ab initio and density functional theory (DFT) methods at the HF/6-31G*, B3LYP/6-31G*, MP2/6-31G*, and MP2/TZVP levels of theory were applied to the investigation of the relative stability of six fullerene isomers of C32. Full geometry optimization of the systems was carried out and electrostatic potential distributions were calculated. ...
