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

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'; ...

Some of the concepts and theoretical techniques employed in recent ab initio studies of the electronic and structural properties of surfaces and interfaces are discussed. Results of total energy calculations for the 2 x 1 reconstructed diamond (111) surface and for stacking faults in Si are reviewed. 30 refs., 8 ...

Some of the concepts and theoretical techniques employed in recent ab initio studies of the electronic and structural properties of surfaces and interfaces are discussed. Results of total energy calculations for the 2 x 1 reconstructed diamond (111) surfa...

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

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

... 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 ...

Ab initio quantum chemical techniques have been used to investigate weakly bund complexes of H20 and SO2. An energy gradient program was used to ...

... 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. ...

We present a method for the computation of cohesive and structural properties of solids. The method is based on a local orbital description of the wavefunctions, an ab initio pseudopotential construction for the ion-core potential, and a local density tre...

This bibliography lists the following reports: Optimized pseudopotentials, Ab-initio materials science and engineering using the molecular dynamics methods for total energy pseudopotential calculations, Oxygen complexes in Si, The enchanting properties of...

A method is presented for the ab initio calculation of configuration interaction in many-electron spectra. It is based on the expansion of the total electronic wavefunction in terms of Hartree-Fock-Slater determinants, as calculated by the programs of Her...

Ab initio calculations have been performed at the SCF level in the STO-3G, 3-21G, and 6-31G* basis sets on a variety of benzenoid and nonbenzenoid aromatic hydrocarbons, ranging from benzene to coronene. It is shown that (1) the enthalpy changes for homodesmic reactions involving only benzenoid aromatics can be computed accurately in all three bases and ...

A constant-pressure ab initio technique is used to study the behavior of CdO at high pressures. A phase transformation from the NaCl-type structure to the CsCl-type structure via a rhombohedral intermediate state is successfully observed through the constant-pressure simulation. This phase change is also analyzed from total ...

We identify the binding sites for adsorption of a single Ge atom on the Si(100) surface using ab initio total energy calculations. The calculated diffusion barriers are in excellent agreement with experimental estimates. Using a large supercell we resolve the controversy regarding the binding geometry and migration ...

We present a new linear scaling ab initio total energy electronic structure calculation method based on the divide-and-conquer strategy. This method is simple to implement, easily to parallelize, and produces very accurate results when compared with the direct ab initio ...

The stability of 4H-SiC at high pressure is studied using a constant-pressure ab initio technique. For the first time, a first-order phase transformation into a rocksalt structure is observed in this material. The 4H-to-RS phase transformation is associated with the shear deformation and its transformation mechanism is different from that of the ...

Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3(-), N5(+), and N5(-) from total atomization energies. Born-Haber cycle calculations, using...

The structures and energies of the molten salt vapor complexes LiAlF[sub 4] and NaAlF[sub 4] are studied using new high level ab initio molecular orbital methods. The structures are determined using Moller-Plesset perturbation theory to second-order and the total energies are determined using a ...

The structures and energies of the molten salt vapor complexes LiAlF{sub 4} and NaAlF{sub 4} are studied using new high level ab initio molecular orbital methods. The structures are determined using Moller-Plesset perturbation theory to second-order and the total energies are determined using a ...

A new high quality three-dimensional potential energy surface for the Ne-CO van der Waals complex is developed using the CCSD(T) method and avqz/avqz+33221 basis set. The ab initio calculation is performed in a total of 1365 configurations with supermolecule method. There is a single global minimum located in a ...

A semiempirical potential energy surface is obtained for the major isotopologue of the water molecule H2 16O that allows the vibration-rotation energy levels in the range of 0-26000 cm-1 to be calculated with an accuracy almost equal to the average experimental accuracy of measurements in the infrared and visible ranges. Variational calculations using this ...

Additivity of Cation- Interactions: An ab Initio Computational Study on -Cation- Sandwich Complexes- sandwiches are the sums of the two corresponding TMA- systems. The contribution of electron correlation- sandwiches and to estimate their binding energies. Morokuma decomposition analysis on the binding energy

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. ...

Ab-initio total energy pseudopotential calculations were performed on talc and pyrophyllite to assess the success of the method in determining the structure of layered silicates. The calculated relative atomic coordinates were in good agreement with experiment. Further calculations were undertaken to determine the probable position of ...

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 ...

... Abstract : This report describes the development and application of ab initio quantum chemical methods that are especially relevant to the study of ...

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

... the potential energy surface provided by modern electronic structure ... screening approach, to determine the equilibrium geometry and composition ...

A workshop, 'Theory Meets Industry', was held on 12-14 June 2007 in Vienna, Austria, attended by a well balanced number of academic and industrial scientists from America, Europe, and Japan. The focus was on advances in ab initio solid state calculations and their practical use in industry. The theoretical papers addressed three dominant themes, namely (i) ...

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...

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 ...

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...

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...

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...

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 ...

We report on the first part of a study of electron-hydrogen scattering, using a method which allows for the ab initio calculation of total and elastic cross sections at higher energies. In its general form the method uses complex 'radial' correlation func...

This study investigates the electronic structure of Group IA cations intercalated into zeolites with the analcime (ANA) framework using ab initio periodic Hartree-Fock theory. The purpose of the study is to gain a better understanding of the role played by electron-donating species in zeolites in general, with specific applications to materials that have ...

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 initio ...

In this paper the authors show that functional groups identified previously from ab initio molecular orbital calculations lead to better UNIFAC predictions of vapor --- liquid equilibrium, especially for mixtures involving molecules in which proximity effects are important. The authors also find that, for the functional groups we have defined, in many ...

Extensive ab initio calculations using a complete active space second-order perturbation theory wavefunction, including scalar and spin-orbit relativistic effects with a quadruple-zeta quality basis set were used to construct an analytical potential energy surface (PES) of the ground state of the [H, O, I] system. A ...

The millimeter-wave rotational spectrum of ethanetellurol has been recorded and assigned for the first time. The spectroscopic study has been complemented by high level ab initio calculations. Geometries, total electronic energies, and harmonic vibrational frequencies have been determined at the MP2 level. A ...

An ab initio investigation of the Si(111)-(7�7) surface reconstruction is undertaken using the state of the art in massively parallel computation. Calculations of the total energy of an ~700 effective-atom supercell are performed to determine (1) the fully relaxed atomic geometry, (2) the ...

Ab initio total-energy calculations are used to investigate adatom vacancies on the Si(111)-(7�7) surface. In striking contrast to recent experimental estimates, vacancy formation energies are calculated to be 0.9 eV on average, with ~0.1-eV variations depending on the type of adatom. We find that faulted or ...

In the equilibrium immiscible Ru-Pd system, the total energies for five possible structures, i.e., A15, D09, D019, L12, and L60, with a stoichiometry of RuPd3 were calculated as a function of lattice constants, based on the Vienna Ab Initio Simulation Package (VASP). The calculation results predicted that the D019, ...

#12;Parallel version of Quantum-ESPRESSO package CPMDCPMD CPMD ab initio total energy calculation electronic energy unique functional of the electron density n(r) � Vanderbilt ultrasoft pseudopotentials pseudopotentials � dimension of system cell � number of electrons and bands � ...

Using a massively parallel computer, we undertake an ab initio investigation of the Si(111)-(7� 7) surface reconstruction. Calculation of the total energy of an �700 effective atom supercell at an 8 Ry plane wave cutoff allows us to determine (1) the energy difference between the (7� 7) ...

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 contributions of ...

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

Rocksalt-structured GeSbTe (GST) phase-change materials contain significant amounts of intrinsic vacancies at one sublattice. On the basis of ab initio total energy calculations, we have shown that the so-called intrinsic vacancies result from geometrical voids that originate from packing spaces for lone pairs of ...

The results of systematic theoretical studies of molecular structure, charge distribution and bond characteristics (bond lengths and bond orders) of potassium - magnesium aspartates ((Asp�)3 K+ Mg2+) in aqueous solution obtained by ab initio quantum-chemical method are presented. The supermolecules including (Asp�)3 K+ Mg2+ + nH2O + (n = 20, 40, 60, ...

Using ab initio density functional calculations, we study the microscopic mechanism of hydrogen release from ammonia borane (NH3BH3) and the reverse process leading to its subsequent recharging with hydrogen. Our total energy surfaces indicate the most favorable pathways to thermally convert the NH3BH3 molecular ...

Based on ab initio total energy calculations, the structural, electronic, mechanic, and magnetic properties of PdHx are investigated. It is found that bulk modulus of PdHx is larger than the metal Pd with the hydrogen storage except Pd4H2. The calculated results for the magnetic moments show that the hydrogen ...

We study the pressure-induced phase transition of MgSe using a constant-pressure ab initio technique and find that the rocksalt-structured MgSe transforms into a FeSi-type structure. Furthermore, we find that this phase transformation is based on a cubic intermediate state with space group of Fbar 43m. The rocksalt-to-FeSi-type phase transition is also ...

The tRNA molecule takes suitable amino acids to the ribosome for the formation of peptide bonds. In starting the peptide chain, the first amino acid taken to the ribosome is methionine. We have carried out calculations on the methionine-tRNA and alanine-tRNA complexes using mixed quantum mechanics ab-initio and molecular mechanics method. The total ...

Recent advances in ab initio quantum many-body methods and growth in computer power now enable highly precise calculations of nuclear structure. The precision has attained a level sufficient to make clear statements on the nature of 3-body forces in nuclear physics. Total binding energies, spin-dependent structure ...

Ab initio total energy calculations based on the exact muffin-tin orbitals method, combined with the coherent potential approximation, have been used to study the thermodynamical and elastic properties of substitutional refractory Ru1-xNixAl alloys. We have found that the elastic constants C' and C11 exhibit ...

We report ab initio calculations of the electronic and magnetic properties of small Co clusters. We performed pseudopotential-based and all-electron calculations. In view of the ``unwritten theorem'' that electron localization enhances the electronic correlations, we have also considered the LDA+U functional, which is tailored for the strong-correlation ...

There are many large-scale nanoscience problems that require ab initio accuracy total energy calculations and atomic relaxations. Unfortunately, the traditional direct ab initio method scales as O(N^3), where N is the number of atoms in the system, and most of the O(N) ...

In this paper we describe how the density matrix renormalization group can be used for quantum chemical calculations for molecules, as an alternative to traditional methods, such as configuration interaction or coupled cluster approaches. As a demonstration of the potential of this approach, we present results for the H{sub 2}O molecule in a standard gaussian basis. Results for the ...

It is now possible to calculate many properties including the energetics (total bond dissociation energies or heats of formation) of molecules containing light elements to high accuracy by using correlation-consistent basis sets, coupled cluster theory an...

The topological diversity of lithium-boron imidazolates LiB(imid)(4) was studied by combining topological enumeration and ab initio DFT calculations. The structures based on zeolitic rho, gme and fau nets are shown to be stable and have high total hydrogen uptake (6.9-7.8 wt.%) comparable with that of MOF-177. PMID:21125132

By use of ab initio density-functional total-energy calculations a point defect with a negative Hubbard U is identified, for the first time, in a chalcogenide system. It is found that in c-As2Se3 two non-interacting neutral Se antisite defects are unstabl...

We investigate how the insertion of an oxygen atom in an atomically thin gold nanowire can affect its rupture. We find, using ab initio total energy density functional theory calculations, that O atoms when inserted in gold nanowires form not only stable but also very strong bonds, in such a way that they can ...

Ab initio total-energy calculations are performed using a conjugate-gradients minimization technique to calculate the properties of various dimer-vacancies and dimer-vacancy complexes on the Si(100) surface. A dimer vacancy is found to be a much more prob...

An efficient first-principles-based mean-field theory is applied to study the site occupations in the Fe-Cr ? phase. It is based on the expansion of the total energy of a random alloy close to the equiatomic composition in the paramagnetic state in terms of the effective on-site interactions and takes into account longitudinal spin fluctuations at high ...

We use the method of Moebius transform introduced by one of us (Chen, Phys. Rev. Lett. 64, 1193 (1990)) to obtain pair potentials for fcc metals from first principles total energy calculations. The derivation is exact for radial potentials and it converge...

In standard treatments of atomic multipole models, interaction energies, total molecular forces, and total molecular torques are given for multipolar interactions between rigid molecules. However, if the molecules are assumed to be flexible, two additional multipolar atomic forces arise because of (1) the transfer of torque between ...

Ab initio calculations of cohesive properties, elastic constants, and phonon dispersions for CoSi2 were performed by means of the Vienna ab initio molecular-dynamics package (VAMP), which makes use of ultrasoft pseudopotentials. In addition, the all-electron full-potential linearized augmented-plane-wave method was ...

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 ...

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)

An ab initio based approach to determine energies and structures for semicoherent interfaces is developed and applied to the Fe(001)/VN(001) system. To account for elastic displacements resulting from the lattice misfit, we compare an atomistic approach using a model potential (embedded-atom method) with a continuum approach using the ...

We established a new ab initio structure optimization technique of determining the valley line on a total-energy surface accurately for the zone-center distortions of ferroelectric perovskite oxides, and applied this technique to the analysis of barium titanate (BaTiO3), lead titanate (PbTiO3), and lead zirconate (PbZrO3). The proposed ...

coupling between two QDs. We first parted the Icosahedral QDs by vaccum and calculated the Total Density

We have investigated by means of ab initio calculations the structural and electronic properties of hydrogenated graphene structures with distinct grain boundary defects. Our total energy results reveal that the adsorption of a single H is more stable at defect. Further total ...

... of ab initio quaru cheiial methtods Lhat are espe,,.ally relevant to the study of high-energy density materials species. Two major quantum chemical ...

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)

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 ...

... artifacts. 3 Miyoshi and Sakai concluded from their ab initio CI ... Quantum chemical calculations (DVM-Xt) of the nonmetallic ...

... eg, SiHl6= has a negative ionization potential. ... V. POTENTIAL ENERGY SURFACES AND DYNAMICS ... initio with effective core potentials, ab initio ...

... 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 ...

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 ...

... Abstract : Quantum chemical methods (ab initio, semiempirical, and Hartree-Fock) were used to calculate the energy of several phosphite ...

... Spectroscopy of Polyatomic Hydrogen Ions; Measurement of Charge Transfer Between D3 ... Ab Initio Calculations On High Spin States ...

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...

... previous grant period have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...

Spectroscopic constants and dissociation energies for the ground states of N2, O2, and F2 determined

... higher diffusion energy barrier and lower diffusion rate make Ti atoms stay in the middle of the hexagon ring much longer (- 1 p see) before jumping ...

... The structures of the entrance channel transition states show the four-body intermediates ... Campus Box 427 Boulder, CO 80309-0427 ...

... Title : A Comparative Study of Nonlocal Density Functional Theory and ab initio Methods: The Potential Energy Surface of sym-Triazine Reactions. ...

Reaching the native states of small proteins, a necessary step towards a comprehensive understanding of the folding mechanisms, has remained a tremendous challenge to ab initio protein folding simulations despite the extensive effort. In this work, the folding process of the B domain of protein A (BdpA) has been simulated by both conventional and replica ...

Reaching the native states of small proteins, a necessary step towards a comprehensive understanding of the folding mechanisms, has remained a tremendous challenge to ab initio protein folding simulations despite the extensive effort. In this work, the folding process of the B domain of protein A (BdpA) has been simulated by both conventional and replica ...

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 ...

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 suggests, for the ...

Vacancy formation and clustering significantly affect structural properties of transition-metal aluminides. Ab-initio quantum mechanical total-energy calculations using a full-potential linear combination of muffin-tin orbitals (LMTO) technique provide a convenient method of studying relevant characteristics such as changes in density of states, and charge ...

We present a powerful new technique for the extrapolation of {ital ab initio} data based on many-body decompositions. Using the new methodology and subtle modifications of the standard correlation consistent basis sets, the H+H{sub 2} barrier height is estimated at 9.603 kcal/mol with a precision of about 0.003 kcal/mol; this extremely accurate result is ...

We present a theoretical investigation on In-related defects in silicon, aimed at understanding In interactions with native defects, vacancy (V) and self-interstitial (I), and at determining the energy parameters needed to efficiently simulate and interpret the experimental profiles. Ab initio total-energy ...

The electronic and structural properties of substitutional and interstitial C impurities in Si, Ge, and SixGe1-x alloy have been investigated based upon ab initio total-energy calculations. For pure materials, we find that the formation energy of substitutional C in Si is 0.81 eV lower than in Ge. For interstitial ...

In this work we show a theoretical study of the electronic and transport properties of superlattices formed by a periodic structure of vacancies (antidots) on graphene nanoribbons. The systems are described by a single-band tight-binding Hamiltonian and also by ab initio total energy density-functional theory ...

The structure for the ground state of the AX deep acceptor center in II-VI semiconductors is identified and the sign of its formation energy is found to be a reliable indicator of p-type dopability. Results from ab initio total-energy calculations on ZnS, ZnSe, ZnTe, and CdTe doped with N, P, As, or Sb show that ...

We study pressure-induced phase transitions in amorphous silicon and crystalline diamond silicon from Gibbs free energies considerations using ab initio total energy calculations. We predict a pressure-induced crystallization of the amorphous network at 2.5 GPa and a first order amorphous to ...

Dimer induced reconstruction and metallicity of Ge(001) surface has been studied using SIESTA. Using slab model, we modeled our surface starting with symmetric dimerization of the surface atoms, which on optimization goes over to asymmetric(buckled) dimerization. It is found that there is a substantial decrease in the total energy of the slab. Calculated ...

Nonlocal response of the surface to the incident light is included into an ab initio one-step photoemission theory. Surface-state normal emission spectra from Be(0001) and Al(100) are calculated by a full-potential scattering method and are found to agree well with the experiment in a wide energy range. The total ...

Possible high-pressure phases of Al are examined by comparing the total energies for three structures: fcc, bcc, and hcp. The energies are calculated using the density-functional formalism and the ab initio self-consistent pseudopotential approach. At zero pressure, the most stable structure is ...

The electronic and structural properties of isolated 3d-transition metal impurities in 3C-, 4H-, and 2H-SiC polytypes have been investigated by total energy ab initio methods. The configurational stability, spin states, formation and transition energies of substitutional (Si sub-lattice) Ti, V, ...

The total energy of a grain boundary in a transition metal is calculated in an {ital ab} {ital initio} manner. Such calculations are now feasible using a plane-wave basis set provided that an optimally convergent pseudopotential is used. The investigation focuses on resolving two competing atomic models for the {Sigma}=5 (001) twist boundary in gold. It is ...

As dislocation motion is resisted by the Peierls barrier, cracks in brittle crystals can be lattice-trapped. The discrete lattice structure of a crystal under loading reflects this behavior of the defect's motion. By determining the energy barrier to crack motion at loads within the range of lattice trapping, the authors are able to obtain a merit function, which ...

The ab initio calculation of electronic energies for numerous configurations of HCO and HOC, and a novel method for fitting the energies to a global surface are reported. This surface is used to calculate all the bound vibrational states of nonrotating HCO and DCO using the Watson Hamiltonian. Some quasibound ...

Nanometer thin intergranular glassy films (IGFs) form in polycrystalline ceramics during sintering at high temperatures. The structure and properties of these IGFs are significantly changed by doping with rare earth elements. We have performed highly accurate large-scale ab initio calculations of the mechanical properties of both undoped and Yittria doped ...

A new high quality three-dimensional potential energy surface for the Ne-CO van der Waals complex is developed using the CCSD(T) method and avqz?avqz+33221 basis set. The ab initio calculation is performed in a total of 1365 configurations with supermolecule method. There is a single global minimum located in a ...

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 ...

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 ...

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 ...

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 ...

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 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 ...

We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe-Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its N�el temperature) as ...

The rhombohedral unit cells of ?-boron crystals and of hypothetical ?-boron quasicrystals were investigated by applying ab initio quantum-chemical methods. The atomic decorations of such unit cells are generally based on a suitable arrangement of eight boron icosahedra, and thus the mechanism of their cohesion was simulated by relaxing a B96 supercluster ...

We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe�Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its N�el temperature) as ...

The results of ab initio calculations for cyclic clusters of methanol, ethanol, 1-propanol, and methanethiol are presented. Dimer, trimer, and tetramer clusters of all four compounds are studied, as are pentamer and hexamer clusters of methanol. From optimized clusters at HG/6--31G**, total energies and binding ...

We present a new potential energy surface (PES) for the ground state (12A') of the chemical reaction Ne+H2+ from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. The ...

We present a new potential energy surface (PES) for the ground state (1(2)A(')) of the chemical reaction Ne+H(2) (+) from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. ...

We employ ab initio calculations of van der Waals complexes to study the potential energy parameters (C(6) coefficients) of van der Waals interactions for modeling of the adsorption of silver clusters on the graphite surface. Electronic structure calculations of the (Ag(2))(2), Ag(2)-H(2), and Ag(2)-C(6)H(6) complexes are performed ...

A general procedure is developed for the computation of the total energies of molecules at their equilibrium geometries. Ab initio molecular orbital theory is used to calculate electronic energies by a composite method, utilizing large basis sets (including diffuse-sp, double-d and ...

of Streptavidin-Biotin Interaction Energy Da W. Zhang, Yun Xiang, and John Z. H. Zhang* Department of Chemistry energies for the streptavidin-biotin binding complex. In this report, the entire streptavidin-biotin report benchmark ab initio computation of interaction energies for ...

The recent literature on the determination of minimum energy conformations by ab initio quantum mechanical techniques is reviewed. The availability of computer-coded analytical first and second derivatives of the Hartree-Fock energy makes possible calculations that will be of significant assistance in structure ...

The reconstruction process of vacancy hole in carbon nanotube is investigated by tight-binding molecular dynamics simulations and by ab initio total energy calculations. In the molecular dynamics simulation, a vacancy hole is found to reconstruct into two separated pentagon-heptagon pair defects. As the result of ...

The heats of formation of CF3, its cation and anion, CF4, C2F4, and :CFCF3 have been calculated at high levels of ab initio molecular orbital theory. Geometries and frequencies were determined, in general, with second-order perturbation theory. Total energies based on coupled cluster calculations with perturbative ...

Superhard cubic boron-carbonitrides (c-BC2N) are studied with the use of the ab initio pseudopotential density functional method. The total energy, lattice constant, bulk and shear moduli, and electronic band structures as well as the electron density of states are calculated for all the possible c-BC2N structures ...

Superhard cubic boron-carbonitrides (c-BC{sub 2}N) are studied with the use of the ab initio pseudopotential density functional method. The total energy, lattice constant, bulk and shear moduli, and electronic band structures as well as the electron density of states are calculated for all the possible c-BC{sub 2}N ...

The structural stability of the rhombohedral and simple cubic phases is studied for the group-VA elements. Using an ab initio pseudopotential total-energy method, the calculated phonon frequencies for the longitudinal acoustic mode at the corner of the simple-cubic Brillouin zone are found to soften. This suggests that all group-V ...

An empirical model and an ab initio calculation of the bulk moduli for covalent solids are used to suggest possible new hard materials. The empirical model indicates that hypothetical covalent solids formed between carbon and nitrogen are good candidates for extreme hardness. A prototype system is chosen and a first principles pseudopotential ...

A scanning tunneling microscopy study and ab initio total energy calculations have identified the atomic-level structure of novel sp;{3}-bonded carbon nanoscale domains formed dynamically from graphite by femtosecond-laser excitation. The structure is characterized by a pseudo sp;{3}-bonding configuration that ...

A comprehensive investigation of oxygen vacancy and interstitial diffusion in ZnO has been performed using ab initio total energy calculations with both the local density approximation (LDA) and the generalized gradient approximation (GGA). Based on our calculation results, oxygen octahedral interstitials are fast ...

An ab initio based model of the temperature-induced ferroelectric phase transition in Sn2P2S6 (SPS) as a prototype of an unconventional ferroelectric is developed. The order parameter in SPS is found as the valley line on a total-energy surface of the zone-center fully symmetrical Ag and polar Bu distortions. Significant nonlinear ...

The package fhi96md is an efficient code to perform density-functional theory total-energy calculations for materials ranging from insulators to transition metals. The package employs first-principles pseudopotentials, and a plane-wave basis-set. For exchange and correlation both the local density and generalized gradient approximations are implemented. The code has a low ...

for T > 10 3 K. This result was adopted by Kingdon and Ferland [24] for photoionized plasma models. Dalgarno, Proc. Phys. Soc. London 67, 1010 (1954). [24] J. B. Kingdon and G. J. Ferland, Astrophys. J. 106 10 -7 Rate coefficient (cm 3 /s) Langevin Kingdon and Ferland total 2s2p 1 P o 2s2p 3 P o 2s 2 1

The total energy of ZnS as a function of unit-cell volume has been calculated for the zinc-blende and rocksalt structures by the first-principles Hartree-Fock linear-combination-of-atomic-orbitals method. The calculated structural properties of both phases and the transition pressure between them agree very well with experiment. The band structure of the ...

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 multimode multistate vibronic interactions between the five lowest electronic states of all three isomers of the difluorobenzene radical cation are investigated theoretically, based on ab initio electronic structure data, and employing a well-established vibronic coupling model. The approach rests on the linear vibronic coupling scheme, augmented by ...

In this paper, we report our investigation of the translational energy relaxation of fast S(1D) atoms in a Xe thermal bath. The interaction potential of Xe-S was constructed using ab initio methods. Total and differential cross sections were then calculated. The latter have been incorporated into the construction ...

In this paper, we report our investigation of the translational energy relaxation of fast S((1)D) atoms in a Xe thermal bath. The interaction potential of Xe-S was constructed using ab initio methods. Total and differential cross sections were then calculated. The latter have been incorporated into the construction ...

We present ab initio calculations of the magnetic moments and magnetic anisotropy energies of small FeCo clusters of varying composition on top of a Cu(100) substrate. Three different cluster layouts have been considered, namely, 2 x 2, 3 x 3, and crosslike pentamer clusters. The ratio of Co atoms with respect to the ...

We present a methodology used to generate interatomic potentials fitted on results of ab initio calculations. Our aim is to obtain models suitable for large-scale simulations in ionic solids. We fitted a potential based on the rigid-ion model in order to investigate the high-temperature properties of lithium oxide. Density-functional theory calculations ...

We applied the fragment molecular orbital (FMO) method, which enables total electronic calculations of large molecules at ab initio level, to the evaluation of binding affinities between the human progesterone receptor ligand-binding domain (PR LBD) and various steroidal ligands. The FMO calculations were performed on the entire ...

Total, electronic, and nuclear energy loss as well as stopping cross sections are calculated for He2+ ions incident on atomic hydrogen, deuterium, and tritium at low to intermediate energies by means of an ab initio, nonadiabatic approach for solving the Schr�dinger equation incorporating ...

Multiconfiguration relativistic Dirac-Fock calculations of KLL Auger energies are reported for neon, argon, uranium, and americium. These selected examples demonstrate the feasibility of this method to calculate completely ab initio, in intermediate coupling, Auger transition energies with a precision of a few eV. ...

The g-Hartree method is adapted to the direct ab initio calculation of transition energies in atoms. For the elements He(Z=2), Li(Z=3), Be(Z=4), Ne(Z=10), Mg/Z=12) and Ar(Z=18) all ionization energies have been computed and found to agree with available e...

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 ...

Full-dimensional, three-state, surface hopping calculations of the photodissociation dynamics of formaldehyde are reported on ab initio potential energy surfaces (PESs) for electronic states S(1), T(1), and S(0). This is the first such study initiated on S(1) with ab initio-calculated ...

The interactions of a He atom with a heavier atom are examined for 26 different elements, which are consecutive members selected from three rows (Li-Ne, Na-Ar, and K,Ca, Ga-Kr) and column 12 (Zn, Cd) of the Periodic Table. Interaction energies are determined using high-quality ab initio calculations for the states of the molecule that ...

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 set with and without ...

In this work, the experimental and theoretical vibrational spectra of 1-bromonaphthalene (1-BN) were studied. FTIR and FT Raman spectra were recorded in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using ab initio Hartree-Fock and density functional ...

This paper will describe the interplay between die electronic structure and structural energetics in simple, complex, and quasicrystalline Al-transition metal (T) intermetallics. The first example is the Ll[sub 2]-DO[sub 22] competition in Al[sub 3]T compounds. Ab-initio electronic total-energy calculations reveal surprisingly large ...

Yohimbine hydrochloride (YHCl) is an aphrodisiac and promoted for erectile dysfunction, weight loss and depression. The optimized geometry, total energy, potential energy surface and vibrational wavenumbers of yohimbine hydrochloride have been determined using ab initio, Hartree-Fock (HF) and ...

We report the results of a theoretical study of resonant vibrational-excitation of N/sub 2/ by low-energy electrons. The vibrational-excitation cross sections were calculated using ab initio fixed-nuclei resonance parameters in the complex-potential or ''boomerang'' model of Dube and Herzenberg. The ...

Ab-initio methods have been employed to investigate the electronic and elastic properties of beryllium chalcogenides (namely BeS, BeSe and BeTe). The electron momentum density, autocorrelation function and energy band gap have been computed using the linear combination of atomic orbitals method. Using the full potential linearized augmented plane-wave and ...

The atomic arrangements and chemical bonding of stable Ge(3)Sb(2)Te(6), a phase-change material, have been investigated by means of ab initio total energy calculations. The results show that an ordered stacking of Ge-Te-Ge-Te-Sb-Te-Te-Sb-Te-Ge-Te- is the most stable configuration in respect that the -Sb-Te-Te-Sb- ...

The high accuracy extrapolated ab initio thermochemistry (HEAT) protocol is applied to compute the total atomization energy (TAE) and the heat of formation of benzene. Large-scale coupled-cluster calculations with more than 1500 basis functions and 42 correlated electrons as well as zero-point ...

Ab initio density functional calculations of the structural and electronic properties of V(2)O(5) bulk and its low-index surfaces are presented. For the bulk oxide and the (010) surface (the natural cleavage plane) a good agreement with experiment and with earlier ab initio calculations is found. For the first ...

This paper will describe the interplay between die electronic structure and structural energetics in simple, complex, and quasicrystalline Al-transition metal (T) intermetallics. The first example is the Ll{sub 2}-DO{sub 22} competition in Al{sub 3}T compounds. Ab-initio electronic total-energy calculations reveal surprisingly large ...

The atomic structures that develop as a function of coverage during deposition of Bi on Ag(111) have been studied using low-temperature scanning tunneling microscopy, low-energy electron diffraction, and ab initio calculations. The growth process involves two sequential stages. At low coverage, Bi atoms are incorporated into the ...

Extensive ab initio calculations using a complete active space second-order perturbation theory wavefunction, including scalar and spin-orbit relativistic effects with a quadruple-zeta quality basis set were used to construct an analytical potential energy surface (PES) of the ground state of the [H, O, I] system. A ...

The results of ab initio molecular orbital calculations of excited states and electronic couplings (for energy transfer) between the B800 and B850 bacteriochlorophyll a (Bchl) chromophores in the peripheral light-harvesting complex (LH2) of the purple photosynthetic bacterium Rhodopseudomonas acidophila are reported. Electronic ...

The project began March 13, 2006, allocated for three years, and received a one year extension from March 13, 2009 to March 12, 2010. It has now completed 48 of 48 total months. The project was focused on using ab initio methods to gain insights into radi...

A theoretical model is presented for deriving effective diabatic states based on ab initio self-consistent field valence bond (VBSCF) theory by reducing the multi-configurational VB Hamiltonian into an effective two-state model. We describe two computational approaches for the optimization of the effective diabatic configurations, resulting in two ways of ...

Direct ab initio molecular dynamics calculations have been carried out for the molecular channel of the photodissociation of propanal, C2H5CHO --> C2H6 + CO, at the RMP2(full)/cc-pVDZ level of ab initio molecular orbital theory. The initial conditions were generated using the microcanonical sampling to put the ...

Thermal Decomposition of Methyl Butanoate: Ab Initio Study of a Biodiesel Fuel Surrogate Lam K for thermal energy or converted to other high value energy sources including ethanol, biodiesel, methanol, hydrogen, or methane.1 Biodiesel is a biologically derived diesel fuel substitute created by chemically

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 ...

The use of damping functions to correct the multipole expansion at short-range is explored. Damping functions for the terms in the multipole expansion can be determined ab initio as a linear combination of analytic functions of the separation between sites, but there are additional short-range terms that have different angular dependence. The approach ...

Ab initio calculations were used to determine the equilibrium geometries and energies of lithium dimethylaminoborohydride. Relative energies of the monomeric and dimeric species were calculated in the gas phase and for the dimethyl ether microsolvated molecules. The most stable structure was a dimer in which the ...

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 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...

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...