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

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...

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...

The stability of bcc-based phases in the Ti-Al-Nb alloy system has been studied from first-principles using a combination of ab-initio total energy and cluster variation method (CVM) calculations. Total energies have been computed for 18 binary and ternar...

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'; 'Ab ...

The ab-initio calculations based on density functional theory (DFT) are performed for Fe and C in their ground state crystal structures. Heats of formation are then calculated for different Fe-C alloy compounds. The lattice constant (volume), bulk modulus and shear moduli for cementite are determined from the total energy calculations. ...

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 ...

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 ...

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 ...

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 ...

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 recently introduced ...

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 recently introduced ...

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 ...

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

The complexity of current {ital ab} {ital initio} quantum-mechanical calculations of the total energy of given distributions of atoms on a periodic lattice often limits explorations to just a few configurations. We show how such a small number of calculations can be used instead to compute the interaction energies ...

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...

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 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 ...

#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 � cut-offs plane wave ...

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 ...

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) and (2� 1) ...

The stiffness and plasticity of boron nitride nanotubes are investigated using generalized tight-binding molecular dynamics and ab-initio total energy methods. Due to boron-nitride BN bond buckling effects, compressed zigzag BN nanotubes are found to unde...

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 ...

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 ...

... 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,. ...

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 ...

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 ...

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, ...

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 ...

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 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 ...

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 ...

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 corner adatoms can be ...

... Title : AB Initio Study of the Electronic Magnetic Circular Dichroism ... functions are determined using as initio quantum chemical techniques including ...

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

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) ...

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, ...

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) ...

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 ...

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 ...

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 technique is an ...

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 ...

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 ...

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 f-polarization functions) and ...

With the aim of establishing a relationship between the electronic structure and the site occupancy within the Cu-O chains, they perform total energy calculations for the sub-stoichiometric compound YBa{sub 2}Cu{sub 3}O{sub 6.5} for various patterns of vacancy ordering. Supercells containing up to four formula units are considered. The effective ...

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 ...

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 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 ...

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 the tendency for deep ...

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 ...

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 amorphous phase ...

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 ...

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 ...

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 ...

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 fcc structure in ...

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, and Cr impurities in ...

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 ...

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 characterizes the ...

... AB-INITIO SIMULATION OF a/2110> ... 4. TITLE AND SUBTITLE AB-INITIO SIMULATION OF a/2110> SCREW DISLOCATIONS γ-TiAl 5c. ...

... ADP012740 TITLE: Ab Initio Study on Spin Polarization of III-V Compound Tips ... Ab initio study on spin polarization of III-V compound tips ...

Ab initio electronic structure methods can supplement CALPHAD in two major ways for subsequent applications to stability in complex alloys. The first one is rather immediate and concerns the direct input of ab initio energetics in CALPHAD databases. The o...

...with this part. The certificate shall be void ab initio for those vehicles causing the...issued, and the certificate may be deemed void ab initio. (C) The manufacturer...with this part. The certificate shall be void ab initio for those vehicles causing...

A new bialkali alanate K2LiAlH6 was synthesized at 320-330 degrees C and 100-700 bar. It was structurally characterized by powder X-ray diffraction. It crystallizes in space group R3m (No. 166) with unit cell parameters a = 5.62068(8) and c = 27.3986(6) A. The Li and K cation sites are mutually exclusive, and Rietveld refinement finds no cation mixing. First-principles total ...

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 treatment of exchange and correlation energies. Key elements of the method include the direct computation ...

... ADP023770. Title : ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper. ...

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

... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : New AB Initio Based Density ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Development of Ab-initio Multibody ...

... 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 ...

... from federally funded research, testing and training ... and agencies for Research Development Test and Evaluation ... Title : An Ab Initio Study of Solid ...

... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : An AB Initio Study of Dimethyl ...

... Accession Number : ADA523968. Title : Ab-initio Simulations of Molten Ni Alloys. Descriptive Note : Journal article (preprint). ...

... 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 ...

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

... Accession Number : ADA351780. Title : Ab Initio and DFT Potential Energy Surfaces for Cyanuric Chloride Reactions. Descriptive Note : Final rept. ...

... Ab initio study on atomic structures and physical properties of CdSe quantum nanodots ... Figure 2. Diagram of covered nanodots. ...

... Title : Ab Initio Study on Atomic Structures and Physical Properties of CdSe Quantum Nanodots. Descriptive Note : Final rept. ...

... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : Ab Initio Study of the Structure ...

... Rydberg I 'Flu state. Demoulin and Jungen (1974) used an ab initio quantum chemical approach, but only at the SCF level ...

... moment has been cancelled a priori for the electronic transition as a function of R(CC), using ab initio quantum chemical techniques including state ...

... from federally funded research, testing and training ... and agencies for Research Development Test and Evaluation ... Title : Ab Initio Study of Ultracold ...

1 AB INITIO STUDIES ON HEXAVALENT PHOSPHORUS COMPOUNDS Ashley L. Wilson* Aberdeen High School Aberdeen, Maryland 21001 ...

... Accession Number : ADA436055. Title : Ab Initio Studies on Hexavalent Phosphorus Compounds. Descriptive Note : Conference paper. ...

... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : Ab Initio Relativistic Study of ...

... Accession Number : ADA440631. Title : Ab Initio Quantum Chemical Study of Electron Transfer in Carboranes. Descriptive Note : Journal article. ...

... 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 ...

... 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. ...

... Ab initio direct trajectory simulation on hydrogen atom transfer in 7-azaindole in the electronic excited state with assist of water molecules ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Ab Initio Direct Trajectory Simulation on ...

... 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 ...

... from federally funded research, testing and training ... agencies for Research Development Test and Evaluation ... Title : AB Initio Propagator Theory of ...

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

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 ...

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 ...

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 structural-energy ...

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 structural-energy ...

We performed high-pressure ADXRD studies on Fe5Si3 and Ni2Si up to 75 GPa. No evidence of the occurrence of a phase transition was observed in them. Fe5Si3 was found to compress isotropically, but an anisotropic compression was observed in Ni2Si. These results are supported by ab initio total-energy calculations, which for Fe5Si3 also ...

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 topmost layer of Ag(111), ...

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 density functional ...

A hybrid computational method intended for simulations of biomolecules in solution is described. The ab initio Kohn-Sham (KS) density functional theory (DFT) method is used to describe the chemically active part of the system and its first solvation shells, while a frozen-density orbital-free (FDOF) DFT method is used to treat the rest of the solvent. The ...

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 calculations within density- ...

We perform ab initio calculations of charged graphene and single-wall carbon nanotubes (CNTs). A wealth of electromechanical behaviors is obtained. (1) Both nanotubes and graphene expand upon electron injection. (2) Upon hole injection, metallic nanotubes and graphene display a nonmonotonic behavior. Upon increasing hole densities, the lattice constant ...

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 ...

The structural and theoretical possibility of lithium vanadium oxide as next generation negative material for advanced Li-ion batteries is discussed. The initial and charged Li1.1V0.9O2 compounds show and hexagonal structures respectively from XRD analysis. The electronic structure and chemical bonding of the Li2.1V0.9O2 and Li1.1V0.9O2 are studied by two kinds of first-principles calculations, ...

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 C, we find that the ...

Using ab initio calculations, we have evaluated two structural descriptions of ?-Al(2)O(3), spinel and tetragonal hausmannite, and explored the relative stability of ?-Al(2)O(3) with respect to ?-Al(2)O(3) with 2.5 at.% of Si, Cr, Ti, Sc, and Y additives to identify alloying element induced electronic structure changes that impede the ? to ? transition. ...

Using ab initio calculations, we have evaluated two structural descriptions of ?-Al2O3, spinel and tetragonal hausmannite, and explored the relative stability of ?-Al2O3 with respect to ?-Al2O3 with 2.5 at.% of Si, Cr, Ti, Sc, and Y additives to identify alloying element induced electronic structure changes that impede the ? to ? transition. The ...

We have studied the structural and magnetic properties of the fcc Fe-Co alloy by means of first-principles calculations. For modeling the alloy we have used the ab-initio self-consistent Virtual Crystal Approximation. The ground state properties was calculated with the Fixed Spin Moment methodology and the Full-Potential LAPW method. For the exchange-correlation potential we ...

Because of the importance of mineral catalyzed decarboxylation reactions in both crude oil formation and, increasingly, biofuel production, we present a model study into the decarboxylation of the shortest fatty acid, propionic acid C(2)H(5)COOH, into an alkane and CO(2) catalyzed by a pyrophillite-like, phyllosilicate clay. To identify the decarboxylation pathway, we searched for a transition ...

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- ...

We perform extensive density-functional theory total-energy calculations and ab-initio molecular dynamics simulations to evaluate the stability and reactivity of surface oxides and hydroxides of InP(001) for photoelectrochemical water cleavage. In order to achieve maximal accuracy, our simulations include the full interface between the semiconductor ...

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 ...