Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point
NASA Technical Reports Server (NTRS)
... from federally funded research, testing and training ... for Research Development Test and Evaluation ... of Molecular Modelling and Ab initio Molecular ...
DTIC Science & Technology
... ADP023770. Title : ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper. ...
... Title : Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper (preprint). ...
... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Ab-Initio Molecular Dynamics Simulations ...
... We carried out ab-initio quantum chemical calculations on these energetic cyclic ethers and generated the electrostatic molecular potential contour ...
Two approaches for directly computing a molecular heat of formation based on sophisticated ab initio
An ab initio centroid molecular dynamics (CMD) method is developed by combining the CMD method with the ab initio molecular orbital method. The ab initio CMD method is applied to vibrational dynamics of diatomic molecules, H2 and ...
NASA Astrophysics Data System (ADS)
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...
National Technical Information Service (NTIS)
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...
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 ...
... Molecular Orbital Studies on Nucleoside Antibodies VIII, Ab Initio Calculation of Cubic Force Constants in Formamide Monomer, Formamide Dimer ...
... Static polarizability and second hyperpolarizability tensors have also been computed for a series of polyenes, polyynes and cumulenes by ab initio ...
... Corporate Author : NATIONAL STANDARD REFERENCE DATA SYSTEM. ... observable properties including the total energy, dissociation energy ...
The adsorption energies of methane and ethane in zeolites are investigated with ab initio molecular orbital theory and density functional theory. In this work we have used zeolite cluster models containing two, three, and five tetrahedral (Si, Al) atoms a...
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...
materials, (iiii) phonon recycling in lasers, and (iv) phonon-assisted photon absorption in photovoltaics. The theoretical treatments include ab initio and molecular dynamic...
Science.gov Websites
... system organized around a common data structure. ... molecular structures; optimize structures using molecul ... ab initio quantum chemical tech- niques ...
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...
The object of this research is to characterize the energetics, spectroscopic properties, and elementary chemical reactions of molecular ions. The approach used will exploit recent developments in ab initio molecular quantum mechanics. Some of the systems ...
For some simple, but nontrivial molecular systems, the interaction potentials are now well determined from ab initio electronic structure calculations ...
NASA Website
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 ...
PubMed
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 ...
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 ...
... Phys.,63 (1975) 2356 11. J.Pople, W.Hehre, P.Schleyer and L.Radom, Ab iritio Molecular Orbital Theory, Wiley, London, 1986 13}
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 ...
Energy Citations Database
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 ...
Ab initio molecular orbital theory has been used to determine the equilibrium geometries, rotational
... 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 ...
In this review we present the techniques of ab initio molecular dynamics simulation improved to its current stage where the analysis of existing processes and the prediction of further chemical features and real-world processes are feasible. For this reason we describe the relevant developments in ab ...
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 ...
... For example, ab initio quantum chemical calculations when combined with reaction rate theory and kinetics modeling can, in principle, be capable ...
... predicting known experimental molecular properties as well as properties predicted by other ab initio studies. Quantum chemical calculations are ...
... We have also calculated further ab-initio atom class-atom class potential functions. Keywords: Quantum chemical electrostatic molecular potential ...
... Abstract : In the research on part I of this project we are carrying out ab-initio quantum chemical calculations and generating electrostatic molecular ...
... cation. Enthalpies of formation were calculated for gas phase N3, N3(-), N5+, and N3 from ab initio molecular orbital theory. ...
Nov 14, 1986 ... Ab initio molecular orbital theory has been used to compute rotational constants to guide spectroscopic searches both in the laboratory and ...
... and many-body perturbation theory (MBPT) methods for the accurate inclusion of electron correlation in ab initio quantum chemical calculations of ...
... 3. Ab initio calculations on ammonia, formamide, pyrrole and pyridine. ... The results given in Appendix II for formamide (HCONH2) are typical of the ...
., Montcourier, P., and Fort, P. (1998). RhoG GTPase controls a pathway that independently activates Rac1 and Cdc
(either ab initio methods or basis sets) for electronic structure calculations, and a graph theory procedure for identifying instantaneous molecular fragment identities...
... Project Manager ... Ab Initio Molecular Orbital Theory, Stability Predictions for N5 ... and Experimental Evidence for the Instability of N5 ...
This report presents ab initio quantum chemical studies of DR for molecular ions that are likely to be important in the atmospheric shock layer. ...
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...
................................................................................ 36 5. Glyoxal as a source of organic aerosol
... progress is reported in development of ab initio computational methods for the electronic structures of molecules employing atomic spectral-product ...
... Title : Analytic Methods Using Computer Algebra with Slater-Type Orbitals for Problems in AB Initio Quantum Chemistry and Molecular Physics. ...
... At present experimental data for ternary Ni-Al-W alloys is not available, and estimates of the accuracy of the Mukai model for liquid density in this ...
... dependent densities in the multicomponent RENE-N4 superalloy, and estimates of the accuracy of the Mukai model for liquid density in this system ...
Dec 8, 2009 ... We examine different molecular structures of nitrogen based on recent observations for analog systems. A structure with Immm symmetry and ...
... AOARD-054095 Hiroshi Mizuseki, Rodion V. Belosludov, Amir A. Farajian, Tomoki Uehara, and Yoshiyuki Kawazoe Institute ...
... Personal Author(s) : Mizuseki, Hiroshi ; Belosludov, Rodion V. ; Farajian, Amir A. ; Uehara, Tomoki ; Kawazoe, Yoshiyuki. Handle / proxy Url : ...
Through the use of a molecular pseudopotential method, we determine the a approximate magnitudes of errors that result when electron affinity determinations of polar negative ions are made through ab initio calculations in which the use of a given basis set yields inappropriate values for permanent and induced dipole moments of the ...
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 ...
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 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 molecular cluster model approach for the description of processes at surface is presented. It involves using finite clusters which contain surface atoms interacting with atomic or molecular adsorbates. Accurate ab initio wavefunctions can be obtained ...
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 energy obtained by ...
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 ...
) to applied external force. We first investigate the mechanical response using an ab initio molecular dynamics where the reaction path depends on the strength and nature of the applied force. We first investigate the response of CB under applied forces using steered molecular dynamics8 (SMD) combined with ...
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
We have calculated molecular geometries and electric polarizabilities for small cadmium selenide clusters. Our calculations were performed with conventional ab initio and density functional theory methods and Gaussian-type basis sets especially designed for (CdSe)(n). We find that the dipole polarizability per atom converges rapidly to ...
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...
Electrical conductivity data of Al for the densities from normal to a fraction of normal density and temperatures up to a few thousand Kelvin are important inputs for the hydrodynamic simulations of exploding aluminium foils. We have generated conductivity data of aluminium, by using ab-initio molecular dynamics simulations and the Kubo Greenwood formula. ...
Gaussian 76 is a general-purpose computer program for ab initio Hartree-Fock molecular orbital calculations. It can handle basis sets involving s, p and d-type gaussian functions. Certain standard sets (STO-3G, 4-31G, 6-31G*, etc.) are stored internally f...
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
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 calculation...
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...
and O�H bond length for a simple water molecule and for water in contact with NaCl surfaces. The resultsAB INITIO MOLECULAR�DYNAMICS SIMULATIONS OF ADSORPTION OF DYE MOLECULES AT SURFACES M. SUGIHARA, H molecules on the NaCl(100) surface. The investigations concentrate on the flat dye molecules trimethin, [C
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
The reaction of C(3P) with H2S to HCS/HSC isomers is investigated with high level ab initio methods. Besides reaction energies to form HCS/HSC, the energetics and properties of different singlet/triplet H2CS reaction intermediates are studied. The combination of ab initio theory and crossed ...
We have developed an ab initio path integral molecular dynamics method based on the fragment molecular orbital method. This �FMO-PIMD� method can treat both nuclei and electrons quantum mechanically, and is useful to simulate large hydrogen-bonded systems with high accuracy. After a benchmark calculation for ...
