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 HF. For the H2 ...
NASA Astrophysics Data System (ADS)
An earlier calculation of hydrocarbon radical hyperfine coupling constants, using the spin-projected unrestricted Hartree Fock (PuHF) method is updated. Unprojected uHF calculations are performed for all the systems studied before. (AIP)
Energy Citations Database
The predicted high pressure superionic phases of water and HF are investigated via ab initio molecular dynamics. These phases could potentially be achieved through either static compression with heating or through shock compression. We study water at dens...
National Technical Information Service (NTIS)
Ab initio molecular electronic structure theory has now progressed to the point where it is capable of making genuine contributions to the understanding of simple chemical reactions. Especially noteworthy examples are the elementary fluorine hydrogen reactions pertinent to the HF chemical laser. The reactions F + H/sub 2/ ..-->.. FH ...
with ab initio studies. The hafnium aluminate thin films with thickness of about 20 nm were deposited of a representative pseudobinary Hf-based material-hafnium aluminate as a function of aluminum concentration in the band gap of the nominally pure HfO2 films referred to as pure HfO2 therein , ...
E-print Network
Accurate binding energies cannot usually be obtained from Hartree-Fock (HF) calculations because the changes in correlation energy are often of the same orders of magnitude as the corresponding changes in the HF energy. The HF binding energies are still o...
Anharmonic vibrational frequencies and intensities are computed for hydrogen fluoride clusters (HF)n
NASA Technical Reports Server (NTRS)
... The optimized geometry of I, C2 H5 -0-ý-N(NO 2 )2 , a precursor to ammonium dinitramide, has been computed at the ab initio HF/6-31G* level. ...
DTIC Science & Technology
... of 1, C2H5-0-C(double bonds oxygen)N(NO2)2, a precursor to ammonium dinitramide, has been computed at the ab initio HF/6-31G* level. ...
The principles that form the basis of all quantum mechanics were first introduced in 1926 by Schroedinger. Since that time these principles have been extended to become the framework of the theory used today. Although the simplicity of the theory cannot b...
Small clusters of group 1 metal complexes with hydrogen fluoride molecules M(HF)n, M = Li, Na, and K, are studied with the ab initio molecular orbital method. The trimer M(HF)3 forms a C3v cluster, in which the metal atom is ionized and the ejected electron is trapped on the top of three equivalent ...
PubMed
The structures and relative stabilities of furoxan and some of its isomers, e.g. the 1,2-dinitrosoethylenes, have been determined by means of ab initio Hartree-Fock and Moller-Plesset calculations. Geometries were optimized at the HF/3-21G, HF/6-31G* and ...
The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, ...
Ab initio calculations for properties of MAX phases Ti2TlC, Zr2TlC, and Hf2TlC J. A. Warner and total density of states of the MAX phases, Ti2TlC, Zr2TlC, and Hf2TlC in the hexagonal P63/mmc space the bulk modulus and structural and electronic properties of M2TlC, with M=titanium Ti , zirconium Zr
Ultra high temperature ceramics including ZrB2 and HfB2 are characterized by high melting point, good strength, and reasonable oxidation resistance. These materials are of interest for use as sharp leading edges for hypersonic vehicles among other applications. Progress in computational modeling of UHTCs has been limited in part due to the absence of suitable interatomic ...
Using ab initio calculations we have computed the lattice constants, bulk moduli, and local and total density of states of the MAX phases, Ti2TlC, Zr2TlC, and Hf2TlC in the hexagonal P63/mmc space group. The results for lattice constants are within 2% of experimental results. The bulk moduli are predicted to be 125, 120, and 131 GPa, ...
The FT-IR and FT-Raman spectra of 3-Bromo phenol (3-BP) molecule have been recorded using Bruker IFS 66V spectrometer in the range of 4000-100 cm(-1). The molecular geometry and vibrational frequencies in the ground state are calculated by using the ab initio Hartree-fock (HF) and DFT (B3LYP) methods with 6-31G (d, p) and 6-311G (d, p) ...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
Ab initio theoretical computations have been performed to reveal the mechanism of the etching reaction of silicon oxide (SiO2) by HF molecules. The probable reaction paths, in which the etching reaction proceeds through four sequential steps to remove a single fragment of SiO2, are presented with their potential energy curves. In every ...
Quantum chemical calculations of energies, geometrical structure and vibrational wave numbers of 3,4-dimethoxybenzonitrile (DMBN) were carried out by the ab initio Hartree-Fock (HF) and density functional theory (DFT) with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The computed values of ...
HF, H2O, CN- and their hydrogen-bonded complexes were studied using state-of-the-art ab initio quantum mechanical methods. A large Gaussian one particle basis set consisting of triple zeta plus double polarization plus diffuse s and p functions (TZ2P + di...
Ab initio calculations at the MP2/6-31G*//HF/3-21G* level have been carried out to study Diels-Alder reactions of 2-substituted-1,3-dienes with sulfur dioxide. The CH ... O electrostatic interaction detected in some of the transition structures located could be decisive in the control of the exo/endo stereoselectivity of this type of ...
Ab initio and density functional theory (DFT) methods at the HF/6-31G*, B3LYP/6-31G*, MP2/6-31G*, and MP2/TZVP levels of theory were applied to the investigation of the relative stability of six fullerene isomers of C32. Full geometry optimization of the systems was carried out and electrostatic potential distributions were calculated. ...
Conformations of trimethoxymethylsilane were studied using matrix isolation infrared spectroscopy and ab initio computations. Trimethoxymethylsilane was trapped in both argon and nitrogen matrixes using heated nozzle effusive sources and a supersonic jet source, in an effort to alter the conformational population in the matrix. Ab ...
The equilibrium structure and the three-dimensional potential energy surface of the Mg-HF van der Waals complex in its ground electronic state have been determined from accurate ab initio calculations using the coupled-cluster method, CCSD(T), in conjunction with the basis sets of triple- through quintuple-zeta quality. The ...
MP2/6-31++G(d,p) ab initio calculations have been performed to estimate the effect of the H-bond on the vibrational properties of HF due to its complexation with aromatic azines (CnN6-nHn, with n = 5, 4 or 3). Our calculations have revealed that the greater is the number of nitrogen atoms in the aromatic ring, the smaller will be the ...
The structure and energetics of the isomeric H-bonded complexes OCxxxHF and COxxxHF have been investigated by ab initio molecular orbital theory and by natural bond orbital analysis. Only with the inclusion of electron correlation is a significant preference for the experimentally observed ...
Ab initio techniques are used to calculate the effective work function (Weff) of a TiN/HfO2/SiO2/Si stack representing a metal-oxide-semiconductor (MOS) transistor gate taking into account first order many body effects. The required band offsets were calculated at each interface varying its composition. Finally, the transitivity of ...
... 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,. ...
We apply ab initio quantum-chemical methods to calculate correlation effects on cohesive properties of Mg, thereby extending the method of increments to metallic systems. Metals require special treatment because of two distinct features. Since the conduction bands are only partially filled, we cannot construct well localized orbitals from them. ...
The optimized geometry and vibrational frequencies of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) were obtained by ab initio HF and DFT/B3LYP levels with complete relaxation in the potential energy surface using 6-31++G(d,p) and 6-311++G(d,p) basis sets. The Fourier-transform infrared (FT-IR) spectrum of DBM has been recorded in ...
A new stable structure has been found for the anion clusters of hydrogen fluoride. The ab initio method was used to optimize the structures of the (HF)(3)(-), (HF)(4)(-), (HF)(5)(-), and (HF)(6)(-) anion clusters with an excess "solvated" electron. Instead of the well-known ...
... Title : AB Initio Study of the Electronic Magnetic Circular Dichroism ... functions are determined using as initio quantum chemical techniques including ...
Computational materials science based on ab initio calculations has become an important partner to experiment. This is demonstrated here for the effect of impurities and alloying elements on the strength of a Zr twist grain boundary, the dissociative adsorption and diffusion of iodine on a zirconium surface, the diffusion of oxygen atoms in a Ni twist ...
Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point
The electronic and optical properties of the 1T-HfX2 (X=S, Se and Te) compounds have been studied using the full potential linear augmented plane wave (FPLAPW) method within the local density formalism. Our calculations show that 1T-HfS2 and 1T-HfSe2 are semiconductors with indirect Kohn Sham gaps of 0.62 and 0.55 eV, respectively, ...
By means of ab initio simulations we investigate the influence of dopants (Si, C, Ge, Sn, Ti, and Ce) on the transition from the monoclinic to the tetragonal phase in HfO2. In this study we focus first on the internal energy only, an approach common to ab initio simulations. In the second step ...
The molecular vibrations of xanthine were investigated in polycrystalline sample, at room temperature by Fourier transform infrared (FTIR) and FT-Raman spectroscopies. The spectra of the molecule have been recorded in the regions 4000-50 cm(-1) and 3500-100 cm(-1), respectively. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were ...
The Fourier transform infrared (FTIR) and FT-Raman spectra of p-cyanobenzoic acid (CBA) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with theoretical ...
The Fourier transform infrared (FTIR) and FT-Raman spectra of 4-amino-2-methylquinoline (AMQ) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The experimental vibrational frequency was compared with the wavenumbers obtained theoretically by ab initio HF and DFT-B3LYP gradient calculations employing the ...
The Fourier transform infrared (FTIR) and FT Raman spectra of p-toluenesulfonyl isocyanate (p-tosyl isocyanate) have been measured. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges have been calculated by using ab initio HF and density functional theory calculation (B3LYP) with ...
We present results from electron paramagnetic resonance (EPR) studies of the EI4 EPR center in 4H - and 6H-SiC . The EPR signal of the EI4 center was found to be drastically enhanced in electron-irradiated high-purity semi-insulating materials after annealing at 700�750�C . Strong EPR signals of the EI4 center with minimal interferences from other radiation-induced defects in irradiated ...
In high resistance AlN irradiated with 2 MeV electrons, an electron paramagnetic resonance (EPR) spectrum, labeled EI-1, with an electron spin S=1/2 and a clear hyperfine (hf) structure was observed. The hf structure was shown to be due the interaction between the electron spin and the nuclear spins of four 27A nuclei with the hf ...
Electronic band gaps and dielectric constants are obtained for amorphous hafnium silicates using first-principles methods. Models of amorphous (HfO2)x(SiO2)1-x for varying x are generated by ab initio molecular dynamics. The calculations show that the presence of Hf gives rise to low-lying conduction states which ...
Hydrogen bonding in DNA bases was investigated using reliable nonempirical ab initio computational methods. Gradient optimization was carried out on 30 DNA base pairs using the Hartree Fock (HF) approximation and the 6-31G basis set. The optimizations wer...
The X-NO2 rotational energy barriers of nitromethane, nitroethylene, nitrobenzene and and a group of nitramines have been computed using a density functional (LDF) procedure, using ab initio Hartree-Fock (HF)-optimized structures of the ground and rotatio...
We have investigated the protonation and reversible covalent hydration of quinazoline in the presence of Li+, Na+, and Ca2+ ions using ab initio quantum mechanical calculations at the MP2/6-31G**//HF/6-31G*level of theory. Proton affinities, enthalpies of hydration at 298.15K (DH...
EPA Science Inventory
In this work, we introduce a new analytical form based on the q-exponential function to build three-dimensional reactive surfaces. The quality of this new function is tested by fitting the ab initio potential energy surface (PES) to the ground state Na+HF reaction. The thermal rate constant and reactive probabilities were determined ...
In sarin (isopropyl methylphosphonofluoridate) there are ten nonequivalent CH oscillators. Ab initio calculations at the HF / 6-311++G(2d, 2p) level have been used to determine the vapour phase local mode parameters, w and wx, for each oscillator in the t...
Dispersion is well known to be important in biological systems, but the effect of electron correlation in such systems remains unclear. In order to assess the relationship between the structure of a protein and its electron correlation energy, we employed both full system Hartree-Fock (HF) and second-order M�ller-Plesset perturbation (MP2) calculations in conjunction with ...
PubMed Central
The present paper reports the energy loss near-edge structure (ELNES) study of monoclinic HfO2 (m-HfO2) and tantalum doped m-HfO2 (Ta0.1Hf0.9O2) thin films prepared by radio frequency magnetron co-sputtering method. A change in the O K-ELNES spectra was observed as the amount of dopant increases. In order to ...
The structural and energetic properties of A2Hf2O7 (A = Dy, Ho, Er) compounds have been investigated by means of ab initio total energy calculations. For Er2Hf2O7 the defect fluorite structure is predicted to be more stable than pyrochlore structure, agreeing well with previous experimental [J. Inorg. Nucl. Chem. ...
The introduction of high-permittivity gate dielectric materials into complementary metal oxide semiconductor technology has reopened the interest in Ge as a channel material mainly due to its high hole mobility. Since HfO(2) and ZrO(2) are two of the most promising dielectric candidates, it is important to investigate if Hf and Zr may diffuse into the Ge ...
Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and ...
Comparison of Hartree-Fock (HF) and Heitler-London (HL) ground-state computations for H2, LiH, Li2, BH, HF, and F2 leads to an approach that is a variational combination of the two approximations. This new HF-HL ab initio method is implemented at three levels. The first level variationally ...
The peptide bond energy variation of methionine-alanine dipeptide was calculated using HF, DFT and MP2 ab-initio methods with 6-31G and 6-31++G** basis sets. The energy variation for MP2 method shows that as the distance between the two amino acid moieties is increased, the interaction energy between them decreases to negative infinity. The Hartree-Fock ...
Temperature and pressure dependent decomposition kinetics of HS2O7-(H2SO4)x (x=1-3) cluster ions were measured in a quadrupole ion trap mass spectrometer. The kinetic data were analyzed with a master equation model to obtain the decomposition energies and energy transfer parameters for channels leading to elimination of sulfur trioxide and in some cases sulfuric acid. The ion cluster structures, ...
Hydrogen bonding in infinite (HF)_infinity and (HCl)_infinity bent (zig-zag) chains is studied using the ab initio coupled-cluster singles and doubles (CCSD) correlation method. The correlation contribution to the binding energy is decomposed in terms of non-additive many-body interactions between the monomers in the chains, the ...
Density functional theory (DFT) was examined for computing energies of temporary anions having negative electron affinities ranging from -8.0 to -0.2 eV. The calculated electron affinities are in good agreement with experiment for {pi}* states and low-energy {sigma}* states. The dependence of the DFT results on basis set was investigated. Comparisons are made with results from traditional ...
Ab initio calculations at the MP2/6-31G* level have shown that variously substituted di- and trifluorobenzenes form non-covalent complexes with benzene that adopt either aromatic-aromatic or H--F binding, the choice being determined by the pattern of fluorination. The binding energies of these structures are from 3.4 to 4.5 kcal ...
The combination of quantum mechanics (QM) and molecular mechanics (MM) methods has become an alternative tool for many applications for which pure QM and MM are not suitable. The QM-MM method has been used for different types of problems, for example, structural biology, surface phenomena, and the liquid phase. In this paper, we have implemented these methods for vitamins, an important kind of ...
... 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...
Code of Federal Regulations, 2010
The interaction between oxygen vacancies and La atoms in the La doped HfO2 dielectric were studied using first principles total energy calculations. La dopants in the vicinity of a neutral oxygen vacancy (VO) show lower formation energy compared to the La defects far from VO centres. La doping in HfO2 leads to the shift of the defect states of oxygen ...
This paper studies the influence of the reagent vibration on the reaction O(1D)+HF?HO+F by using a quasi-classical trajectory method on the new ab initio 1A' ground singlet potential energy surface (G�mez-Carrasco et al 2007 Chem. Phys. Lett. 435 188-193). The product angular distributions which reflect the vector correlation are ...
The charge transfer in collisions of C{sup 2+} ions with the HF molecule has been studied by means of ab initio quantum chemistry molecular methods followed by a semiclassical dynamical treatment in the keV collision energy range. The mechanism of the process, in particular its anisotropy, has been investigated in detail in connection ...
The anisotropic shear moduli and strengths of hard fcc-TMN (TM=Ti, Zr, Hf) have been calculated by ab initio density functional theory in order to better understand their shear resistance. TiN shows the largest shear strength among the three nitrides, being consistent with the known facts that TiN is harder than ...
The molecular geometry, the normal mode frequencies and corresponding vibrational assignment of melaminium phthalate (C3H7N6+.C8H5O4(-)) in the ground state were performed by HF and B3LYP levels of theory using the 6-31G(d) basis set. The optimized bond length numbers with bond angles are in good agreement with the X-ray data. The vibrational spectra of melaminium phthalate ...
The interaction between oxygen vacancies and La atoms in the La doped HfO(2) dielectric were studied using first principles total energy calculations. La dopants in the vicinity of a neutral oxygen vacancy (V(O)) show lower formation energy compared to the La defects far from V(O) centres. La doping in HfO(2) leads to the shift of the defect states of ...
We report ab initio calculations of the phonon spectra for hafnium nitride (HfN) at ambient and high pressures. The calculation of phonon density of states using the density functional perturbation theory including external perturbations like strains and electric fields in periodic systems carried out for full Brillouin zone. The ...
The influence of polar molecules on the proton transfer potential within a H-bonded system is studied by ab initio methods, An external HF molecule is placed in various locations in the vicinity of the (H{sub 2}OH {center dot} {center dot} OH{sub 2}){sup +} system. It was found that for most positions the effects on the proton transfer ...
The quadrupolar hyperfine interactions of in-diffused (111)In --> (111)Cd probes in polycrystalline isostructural Zr(4)Al(3) and Hf(4)Al(3) samples containing small admixtures of the phases (Zr/Hf)(3)Al(2) were investigated. A strong preference of (111)In solutes for the contaminant (Zr/Hf)(3)Al(2) minority phases was observed. ...
The quadrupolar hyperfine interactions of in-diffused ^{111}\\mathrm {In} \\to {^{111}\\mathrm {Cd}} probes in polycrystalline isostructural Zr4Al3 and Hf4Al3 samples containing small admixtures of the phases (Zr/Hf)3Al2 were investigated. A strong preference of 111In solutes for the contaminant (Zr/Hf)3Al2 minority phases was ...
The electronic structure and relative stability of monoclinic, tetragonal, and cubic phases of HfO2 with Ti doping in the range of 3.125%-37.5% are studied by means of first-principles calculations. The dielectric response, and electron and hole trapping properties of Ti-doped monoclinic HfO2 are calculated using a hybrid density-functional B3LYP. The ...
High-resolution infrared laser spectroscopy is used to study the CH{sub 3}...HF and CD{sub 3}...HF radical complexes, corresponding to the exit-channel complex in the F+CH{sub 4}{yields}HF+CH{sub 3} reaction. The complexes are formed in helium nanodroplets by sequential pickup of a methyl radical and a HF molecule. ...
In the equilibrium immiscible Hf-Nb system characterized by a positive heat of formation, five Hf-Nb metallic glasses with overall compositions of Hf{sub 84}Nb{sub 16}, Hf{sub 65}Nb{sub 35}, Hf{sub 45}Nb{sub 55}, Hf{sub 38}Nb{sub 62}, and Hf{sub ...
... 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 ...
NASA Website
... 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 ...
Intermolecular interaction potentials of the trifluoromethane dimer in 15 orientations have been calculated using the Hartree-Fock (HF) self-consistent theory and the second-order M�ller-Plesset (MP2) perturbation theory. Single point energies at important geometries were also calibrated by the coupled cluster with single and double and perturbative triple excitation ...
We present refinements of the SIBFA molecular mechanics procedure to represent the intermolecular interaction energies of Zn(II). The two first-order contributions, electrostatic (E(MTP)), and short-range repulsion (E(rep)), are refined following the recent developments due to Piquemal et al. (Piquemal et al. J Phys Chem A 2003, 107, 9800; and Piquemal et al., submitted). Thus, E(MTP) is augmented ...
Time-dependent density functional theory (TD-DFT) and correlated ab initio methods have been applied to the electronically excited states of vitamin B12 (cyanocobalamin or CNCbl). Different experimental techniques have been used to probe the excited states of CNCbl, revealing many issues that remain poorly understood from an electronic structure point of ...
Several variations of ab initio based molecular models for hydrogen fluoride (HF) are examined by Monte Carlo molecular simulation to determine their bulk-phase properties. The models are taken from the literature, and represent fits of functional forms to the potential energy surface of the HF dimer as given by ...
We report on the determination of a high quality ab initiu potential energy surface (PES) and dipole
The reaction of HF molecules with brucite, Mg(OH)(2), leading to the formation of Mg(OH)(2-x)F(x), was theoretically studied by ab initio density functional theory (DFT) with periodic boundary conditions. We proposed as mechanism for this reaction four elementary steps: adsorption of the HF molecule, OH(-) ...
The FT-IR and FT-Raman spectra of m-Xylol molecule have been recorded using Bruker IFS 66V spectrometer in the range 4000-100cm(-1). The molecular geometry and vibrational frequencies in the ground state are evaluated using the Hartree-fock (HF) and B3LYP with 6-31+G (d, p), 6-31++G (d, p) and 6-311++G (d, p) basis sets. The computed frequencies are scaled using a suitable ...
In a crossed molecular-beam study we have measured angular and time-of-flight distributions of the product LiF from the reaction Li + HF(upsilon = 0)-->LiF + H at various collision energies ranging from 97 to 363 meV for three markedly different rotational state distributions of HF obtained at nozzle temperatures close to 315, 510, and 850 K. ...
Dispersion is well-known to be important in biological systems, but the effect of electron correlation in such systems remains unclear. In order to assess the relationship between the structure of a protein and its electron correlation energy, we employed both full system Hartree-Fock (HF) and second-order M�ller-Plesset perturbation (MP2) calculations in conjunction with ...
We perform a systematic ab initio study of the electronic and atomic structure of semicoherent interfaces between bcc Fe and NaCl MX ( M=Sc , Ti, V, Cr, Zr, Nb, Hf, Ta; X=C or N). The interface energetics is accessed by using a Peierls-Nabarro framework, in which ab initio data for the ...
The FT-IR and FT-Raman vibrational spectra of 1,3-dichlorobenzene (1,3-DCB) have been recorded using Bruker IFS 66V Spectrometer in the range 4000-100cm(-1). A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry, vibrational ...
The impact of quantum nuclear effects on hydrogen (H-) bond strength has been inferred in earlier work from bond lengths obtained from path integral molecular dynamics (PIMD) simulations. To obtain a direct quantitative assessment of such effects, we use constrained-centroid PIMD simulations to calculate the free energy changes upon breaking the H-bonds in dimers of HF and ...
The isomer shift for the 23.87 keV M1 resonant transition in the 119Sn nucleus is calibrated with the help of ab initio calculations. The calibration constant ?(119Sn) obtained from Hartree-Fock (HF) calculations (?HF(119Sn)=(0.081+/-0.002)a0-3 mm/s) and from second-order M�ller-Plesset (MP2) calculations ...
The mechanism of scandium cation Sc+(1D) insertion into HF, HCl, H2O, H2S, NH3, PH3, CH4, and SiH4 has been investigated by ab initio molecular theory. All these reactions involve the initial formation of intermediate complexes followed by an H-atom migration process via a transition state to insertion products. The Sc+(1D) insertion ...
The FT-IR and FT-Raman vibrational spectra of alpha-chlorotoluene have been recorded using Perkin-Elmer 180 spectrometer in the range 3600-10 cm(-1) in the solid phase. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry, ...
Deleterious effects of radiation in nuclear reactor systems cause material degradation and the potential for component failure. Radiation damage is fundamentally due to freely migrating point defects produced in collision cascades. A reduction in the freely migrating point defect population should, then, reduce radiation damage and increase component lifetime. The addition of oversized solute ...
Ab Initio polarizabilities of thiophene, fulvene and cyclopentadiene based conducting oligomers and polymers and their cyano derivatives have been calculated using the Hartree-Fock (HF), configuration interaction (singles) (CIS ) and density functional (DF) theories with 3-21G* basis using Gaussian software. The main motivation of this ...
The ground state of odd-N polyynic oligomers CNH2 features kink solitons in carbon-carbon bond-length alternation (BLA) patterns. We perform a systematic first-principles computational study of neutral and singly charged kinks in long oligomers addressing relationships between BLA patterns, electron energy gaps, and accompanying distributions of spin and charge densities, both in vacuum and in the ...
Recently developed ab initio pseudopotentials are employed to examine the molecular electronic structure of ZnF/sub 2/ in an LCAO-HF treatment. Comparison with a previous all-electron study reveals excellent agreement. Comparison with a pseudopotential treatment of ZnCl/sub 2/ shows, as expected, that the fluoride is far more ionic ...
Ab initio quantum chemistry methods based upon many-body perturbation theory (MBPT) and coupled-cluster (CC) theory have been developed and applied to potential energy surfaces for transient molecules. Studies included decomposition pathways for formaldehyde, methanol, the formyl radical and the inorganic radical HIF. MBPT/CC methods were extended to ...
Thermal stability of small cage clusters known as Platonic hydrocarbons (tetrahedrane, cubane) was studied over a wide temperature range using tight-binding molecular dynamics simulation. Activation energies and frequency factors in the Arrhenius equation were obtained for these clusters. Ab initio calculations using HF, and B3LYP ...
Vibrational spectral analysis aided by ab initio computations at HF/6-31G (d) level of an anti-inflammatory drag, ethenzamide, has been carried out using NIR FT-RAMAN and FT-IR spectra. The present investigation deals with the analysis of structural and bonding features responsible for biological activities, nature of hydrogen bonding, ...
The optimized geometry of 1, C2H5-O-C(double bonds oxygen)N(NO2)2, a precursor to ammonium dinitramide, has been computed at the ab initio HF/6-31G* level. We find no structural evidence that 1 exists in the ionic form, C2H5-O-C(triple bonds)O + N(NO2)2(-...
