... Title : Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields. ...
DTIC Science & Technology
... 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 ... agencies for Research Development Test and Evaluation ... Title : Ab Initio Study of the Structure ...
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)
The equilibrium structure, dipole moment, harmonic vibrational frequencies, and infrared intensities
NASA Technical Reports Server (NTRS)
Dynamical calculations are performed on an ab initio potential energy surface for KCN. Approximate variational solutions of the vibrational Eckart hamiltonian are presented for several states. Fundamental vibrations are found to lie at 302�7 cm-1 and 119�7 cm-1. An effective rotational hamiltonian is solved for ...
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 ...
Energy Citations Database
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 ...
... More recently, extensive calculations on the nitrogen oxides were conducted employing the density functional method (ref 2) in conjunction with a ...
... The results are in perfect qualitative and good quantitative agreement with existing experimental VCD spectra except in the CH stretching region of ...
... nucl, electr) degrees of freedom are decoupled from the vibrational/rotational (vib, rot) ones (Born- Oppenheimer approximation), and further that ...
The unimolecular decay lifetimes of several vibrational states of HN2 are determined on the basis of
We compare calculations of infrared (IR) spectra of water confined between non polar surfaces, carried out using ab initio and classical simulations. Ab-initio results show important differences between IR spectra and vibrational density of state, unlike classical simulations. These differences originate from ...
The vibrational frequencies of the electronic ground state of resorcinol have been determined via laser-induced dispersed fluorescence spectroscopy. An assignment based on comparison with ab initio calculations on the MP2 and B3LYP (6-311 G (d,p)) level is presented.
Vibrational frequency shift upon the 1 : 1 acetone-iodine complex formation was determined from geometries optimized at the SCF (Self Consistent Field) and MP2 (Moeller-Plesset Second Order Perturbation) levels using the ab initio MO (Molecular Orbital) t...
National Technical Information Service (NTIS)
Theoretically determined frequencies and absorption intensities are reported for the vibrational spectrum of the covalent HOOOH and hydrogen bonded HO---HOO intermediates that may form in the reaction of the hydroxyl and hydroperoxyl radicals. Basis sets ...
Iodine heptafluoride, the most studied prototype of a heptacoordinated molecule, had presented many mysteries concerning its spectroscopic and structural properties. It is shown by ab initio calculations and a reexamination of the vibrational spectra and ...
This report does a complete vibrational spectal analysis of 2-methylpropionyl fluoride using microwave, infrared, and Raman spectra.
In-situ FT-IR vibrational spectra of thiocyanate ions absorbed on polycrystalline Ag electrodes as a function of electrode potential and electrolyte concentration are reported. Interpretation of the results are performed with the help of ab initio SCF cal...
An analysis of the vibrational spectra of the bent triatomic molecules HCO and DCO has been performed using algebraic methods. A model based on coupled U(2) algebras has been proposed for the description of the vibrational spectrum of HCO. The vibron model, based on the U(4) Lie algebras, has then been applied for the calculation of the ...
the first few lines in the P, Q, and R branches of the rotation-vibration spectra of the equilateral-triangle molecular ions H/sub 3//sup +/ and D/sub 3//sup +/, obtained by ab initio nonperturbative calculations, are reported. Comparison with observations indicates an accuracy better than 1% was obtained for both the infrared-active ...
The phonon dispersion relations of bulk hexagonal boron nitride have been determined from inelastic x-ray scattering measurements and analyzed by ab initio calculations. Experimental data and calculations show an outstanding agreement and reconcile the controversies raised by recent experimental data obtained by electron-energy loss spectroscopy and ...
PubMed
In this work, the structure of symmetric N2O3 was investigated using ab initio methods. Bond lengths and bond angles were determined using the 6-31 G* and the 6-311 G* basis sets using both SCF and MP2 theory. At the highest level of theory considered in ...
Ab initio calculations using the Molier-plesser perturbation theory were carried out on the H-atom abstraction reaction from dibromomethane by hydroxyl radical attack. Geometry optimization and vibrational frequency calculations at the MP2 level were perf...
The ab initio calculation of harmonic force fields using post-self-consistent (post-SCF) methods has recently increased greatly in efficiency. As a result, accurate post-SCF harmonic force fields are now achievable for experimentally accessible chiral mol...
Ab initio calculations using the Molier-plesser perturbation theory were carried out on the H-atom abstraction reaction from dibromomethane by hydroxyl radical attack. Geometry optimization and vibrational frequency calculations at the MP2 level were performed on all reactants, p...
EPA Science Inventory
The vibrational Stark effect together with nuclear relaxation and vibrational contributions to the static molecular electric properties of the N{sub 2}O molecular are computed using ab initio molecular orbital theory. Contributions to the molecular properties are computed by finite-difference techniques involving ...
can estimate vibrational activity for every separate atom, examining the components of the eigenvector it decays more slowly and a whole cluster of vibrationally active atoms to the side of the void. Vibrational density of states upper panel and inverse participation ratio lower panel for 216-atom DTW model
E-print Network
We report a highly correlated multireference configuration interaction calculation of the near-equilibrium potential energy surface of ozone using a large correlation consistent basis set. Three-dimensional analytical expressions are obtained for the potential energy and dipole moment functions using least-squares fits to ab initio points near the C{sub ...
State-of-the-art, calibrated ab initio quantum chemical calculations have been performed to obtain accurate structures, energies, and vibrational frequencies of the lowest singlet states of HNS and NSH, which are closed-shell states. Enthalpies of formati...
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 ...
Assisted by prior ab initio correlated predictions of the vibrational spectral, the first experimental observation of the H2-BH3 complex was recently reported by Tague and Andrews (TA). However, H2-BH3 has been calculated to have Cs symmetry, following th...
We described our theoretical advances that influenced the experimental creation of vibrationally and translationally cold polar molecules. Our analysis includes multi-channel bound states of ground and excited electronic states. We excellent agreement wit...
The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determine...
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... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
The vibrational frequencies of a seris of XY sub 4 /sup -n/ anions (BeF sub 4-2 , BF sub 4- , AlF sub 4- , MgCl sub 4-2 , and AlCl sub 4- ) have been calculated by ab initio molecular orbital theory using the 3-21G and 6-31G* basis sets. The predicted har...
We present a new technique which allows the fully {\\em ab initio} calculationof the chemical potential of a substitutional impurity in a high-temperaturecrystal, including harmonic and anharmonic lattice vibrations. The techniqueuses the combination of thermodynamic integration and reference modelsdeveloped recently for the {\\em ...
The infrared spectrum of methyl tert-butyl ether (MTBE) in liquid water has been studied using both FTIR absorption and FTIR-ATR spectroscopy in conjunction with ab initio calculations. Compared to the liquid MTBE IR spectrum, the C-O and C-C stretching vibrational frequencies of MTBE in water are found to shift to the red and blue by ...
We have used high resolution neutron vibrational spectroscopy to study the vibrations of the model compound for arene-to-metal bonding, benzene chromium tricarbonyl, and its mesityl analogue. It is shown that all previously published assignment schemes, based on optical spectroscopy alone, are wrong, and new assignments are given in agreement with ...
A general expansion is derived for the transition moment between two nondegenerate vibrational states of a polyatomic molecule. This analysis is combined with ab initio surfaces for the potential energy and the dipole moment of water vapor to predict integrated band absorption intensities. Calculations are compared with experiment for ...
Structural and spectroscopic properties of hydrazine, H(2)N-NH(2), it being a floppy or fluxional molecule in a vacuum, are investigated by means of ab initio molecular dynamics, ab initio path integral molecular dynamics, and ab initio ring polymer molecular dynamics ...
... 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 Quantum Chemical Investigations of Solubilities in Supercritical Solutions. Descriptive Note : Conference Paper,. ...
... Title : AB Initio Study of the Electronic Magnetic Circular Dichroism ... functions are determined using as initio quantum chemical techniques including ...
We present full-dimensional potential energy surfaces (PESs) for hydrated chloride based on the sum of ab initio (H(2)O)Cl(-), (H(2)O)(2), and (H(2)O)(3) potentials. The PESs are shown to predict minima and corresponding harmonic frequencies accurately on the basis of comparisons with previous and new ab initio ...
In this paper it is shown that the complex Shavitt functions Fn(z) can be interpolated in the same way as the real Shavitt functions Fn(x) in electronic structure theory. This greatly accelerates the evaluation of exchange integrals in a mixed Gaussian and plane-wave basis. Together with other approximations reported previously this extends applications of ab ...
We present a combined computational and experimental study on structural and electric properties of recently synthesized heteroaromatic dyes and their simple aggregates. Ab initio and density functional theory calculations are carried out to investigate ground state and excited state properties along with their modulation induced by the solvent described ...
The results of ab initio calculations of the vibronically averaged components of the anisotropic magnetic hyperfine tensor in the low-lying vibronic species of the X2? electronic state of the HCCS radical are reported. The electronically averaged hyperfine coupling constants for hydrogen, deuterium, 13C and 33S are obtained as functions of two bending ...
Zinc oxide is a key material for optoelectronic applications, whose transport properties are typically dominated by the lattice vibrations. We report here the phonon-dispersion relations of wurtzite ZnO at 10 K, as determined by using inelastic neutron scattering. The experimental data are analyzed with the aid of ab initio ...
The study and prediction of chemical reactivity is one of the most influential contributions of quantum chemistry. A central concept in the theoretical treatment of chemical reactions is the reaction pathway, which can be quite difficult to integrate accurately and efficiently. This talk will outline our developments in the integration of these pathways on ab ...
The INS spectra of several azines have been analyzed starting from force constant matrix calculated via ab initio and DFT methods. In order to reproduce both vibrational frequencies and intensities, the initial force constants must be fitted until the spectral profile is reproduced. We have checked the various ways which can be ...
The structures and relative energies of Pt(PH/sub 3/)XY isomers are investigated with use of ab initio molecular orbital theory and effective potentials. In particular, the cis and trans isomers of the dihydride, dichloride, and hydrochloride are studied. In all cases, the trans isomer is the more stable. Available experimental information is in good ...
An ab initio calculation of a secondary isotope effect on a bond length has been carried out for the first time. Single determinant molecular orbital computations indicate that the mean C--C bond length at 0 degreeK is longer in C$sub 2$H$sub 6$ than in C$sub 2$D$sub 6$ by 0.0015 A. A comparison with model calculations supports a steric ...
Following our recent studies of the thermodynamic properties of azaspiropentane and borospiropentane, in consideration of their usefulness as new potential high energy materials, we follow up with ab initio calculations on the thermodynamic properties of azaborospiropentanes. Properties reported in this study include optimized structural parameters, ...
The energies and molecular structures of the highly coordinated species PH5, SH4, SH6, C1H3, and C1H5 have been derived by ab initio computations. Of particular interest are C1H3, which is of C2v symmetry, and C1H5, which is C4v. MP2 vibrational frequenci...
The aim of the study was to explore the limits of initio methods towards the description of excited vibrational levels up to the dissociation limit for molecules having more than two electrons. To this end a high level ab initio potential energy function was constructed for the four-electron LiH molecule in order ...
Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point
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) ...
The infrared spectra (3500-50 cm(-1)) of the gas and solid and the Raman spectra (3500-50 cm(-1)) of the liquid and solid have been recorded for 1-fluoro-2-butyne, CH3-C-triple bond-C-CH2F. Equilibrium geometries and energies have been determined by ab initio and hybrid DFT methods using a number of basis sets. A vibrational assignment ...
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 ...
Incoherent inelastic neutron scattering is used to probe the effects of dihydrogen bonding on the vibrational dynamics in the molecular crystal of ammonia borane. The thermal neutron energy loss spectra of (11)B enriched ammonia borane isotopomers ((11)BH(3)NH(3), (11)BD(3)NH(3), and (11)BH(3)ND(3)) are presented and compared to the vibrational power ...
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 ...
Three-dimensional quantum mechanical calculations on the vibrational predissociation dynamics of HeI2 B state complex are performed using a potential energy surface accurately fitted to unrestricted open-shell coupled cluster ab initio data, further enabling extrapolation for large I2 bond lengths. A Lanczos iterative method with an ...
Ion association of solutions of lithium perchlorate in N,N-dimethylformamide, acetonitrile, tetrahydrofuran, acetone, methyl acetate and other organic solvents have been investigated by infrared and Raman spectroscopy, respectively. The spectroscopically free ion, contact ion pair and dimer are fingerprint by the curve fitting of upsilon1 band of. The most stable geometries of contact ion pairs ...
A quantum mechanical investigation of the vibrational and rotational deactivation of NO(+) in collisions with He atoms in the cold and ultracold regime is presented. Ab initio potential energy calculations are carried out at BCCD(T) level and a new global 3D potential energy surface (PES) is obtained by fitting ab ...
A quantum mechanical investigation of the vibrational and rotational deactivation of NO+ in collisions with He atoms in the cold and ultracold regime is presented. Ab initio potential energy calculations are carried out at BCCD(T) level and a new global 3D potential energy surface (PES) is obtained by fitting ab ...
We present an in-depth analysis of the electronic and vibrational band structure of uniaxially strained graphene by ab initio calculations. Depending on the direction and amount of strain, the Fermi crossing moves away from the K point. However, graphene remains semimetallic under small strains. The deformation of the Dirac cone near ...
Properties of the ground electronic states of neutral p-benzoquinone and the related p-benzosemiquinone radical anion are determined by ab initio calculations. The structures, vibrational frequencies, and frequency assignments of the neutral are found to be in good agreement with the most recent experimental determinations. Good ...
Vibrational eigenfunctions are calculated on-the-fly using semiclassical methods in conjunction with ab initio density functional theory classical trajectories. Various semiclassical approximations based on the time-dependent representation of the eigenfunctions are tested on an analytical potential describing the chemisorption of CO ...
We have performed an approximate ab initio calculation of vibrational properties of hydrogenated amorphous silicon (a-Si:H) using a molecular dynamics method. A 216-atom model for pure amorphous silicon (a-Si) has been employed as a starting point for our a-Si:H models with voids that were made by removing a cluster of silicon atoms ...
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 ...
An automatic procedure for the generation of potential energy surfaces based on high level ab initio calculations is described. It allows us to determine the vibrational wave functions for molecules of up to ten atoms. Speedups in computer time of about four orders of magnitude in comparison to standard implementations were achieved. ...
Ab initio calculations have been performed to study the molecular structures and the vibrational levels of the low-lying ionic states (2A2, 2B1, 2A1 and 2B2) of thiophene. The equilibrium molecular structures and vibrational modes of these states are presented. The theoretical ionization intensity curves including ...
The interaction between the triplet state of the lithium dimer, (7)Li(2), with (4)He is obtained from accurate ab initio calculations where the vibrational dependence of the potential is newly computed. Vibrational quenching dynamics within a coupled-channel quantum treatment is carried out at ultralow energies, ...
Computational calculations of Becke's three-parameter hybrid method using the LYP correlation functional (B3LYP) have been performed on (B12H12)2? dodecaborane anions with different boron isotopic compositions. This was done in order to investigate isotopic dependence of vibrational spectral properties of B12 icosahedra, and for comparison of the optical ...
The structure, potential energy functions and vibrational spectra of several cyclic and bicyclic molecules have been investigated using several spectroscopic techniques and high-level ab initio and density functional theory (DFT) calculations. Laser induced fluorescence and Raman spectroscopies were used to study the conformation of 2- ...
The vibrational spectrum of B2C has been observed for the first time in solid argon by Fourier-transform infrared spectroscopy. Absorption frequencies of the three boron isotopomers of cyclic symmetric B2C, previously deduced by ab initio theory, are in accord with measured frequencies, which enables assignment of an absorption at ...
The structure and harmonic vibrational frequencies of Be sub 4 have been predicted using ab initio molecular electronic structure theory. A better than double zeta plus polarization (DZ+P) basis set was used in conjunction with self-consistent-field (SCF)...
The authors report molecular orbital calculations and experimental observations of the vibrational properties of CHF{sub 2} and CDF{sub 2} radicals and cations. This molecule is a reaction product of the atmospheric reaction of OH with CH{sub 2}F{sub 2}. REMPI measurements provide vibrational frequencies for the molecules, along with spectroscopic ...
A three-dimensional time-dependent quantum dynamics approach using a recently developed ab initio potential energy surface is applied to study ro-vibrational excitation in N+N2 exchange scattering for collision energies in the range 2.1- 3.2 eV. State-to-...
The calculation of thermochemical data requires accurate molecular energies and heat capacities. Traditional methods rely upon the standard harmonic normal-mode analysis to calculate the vibrational and rotational contributions. We utilize path-integral Monte Carlo for going beyond the harmonic analysis and to calculate the vibrational and rotational ...
The calculation of thermochemical data requires accurate molecular energies and heat capacities. Traditional methods rely upon the standard harmonic normal mode analysis to calculate the vibrational and rotational contributions. We utilize path integral Monte Carlo (PIMC) for going beyond the harmonic analysis, to calculate the vibrational and rotational ...
DOE Information Bridge
The vibrational spectra of 1,2-dibromoethane and the meso and chiral forms of 1,2-dideuterio-1,2-dibromoethane are presented. The experimental spectra were obtained for neat liquid samples as well as for the molecules isolated in low-temperature matrices....
In this work we continue studying the ethane vibrational spectra, being considered as a non-rigid molecule. The ? internal rotational angle and the symmetric and anti-symmetric CH stretching normal modes will be the variables under study. Using ab-initio calculations a three dimentional potential is obtained, and finally a three dimentional Far-infrared ...
The complete cubic and quartic force fields of H3SiF and H3SiC1 are predicted from ab initio SCF calculations using the 6-31G basis set. The computed geometries, rotational constants, vibrational wavenumbers, anharmonicity constants, vibration-rotation in...
Anharmonic vibrational frequencies and intensities are computed for hydrogen fluoride clusters (HF)n
We have demonstrated the use of ab initio molecular dynamics (AIMD) trajectories to compute the vibrational energy levels of molecular systems in the context of the semiclassical initial value representation (SC-IVR). A relatively low level of electronic structure theory (HF/3-21G) was used in this proof-of-principle study. ...
We report a new ``spectroscopic'' potential energy surface (PES) of formaldehyde (H212C16O) in its ground electronic state, obtained by refining an ab initio PES in a least-squares fitting to the experimental spectroscopic data for formaldehyde currently available in the literature. The ab initio PES was computed ...
We report a new "spectroscopic" potential energy surface (PES) of formaldehyde (H(2) (12)C(16)O) in its ground electronic state, obtained by refining an ab initio PES in a least-squares fitting to the experimental spectroscopic data for formaldehyde currently available in the literature. The ab initio PES was ...
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 structures and vibrational spectra of adenine in two tautomeric forms (N{sub 9}-H and N{sub 7}-H) and 9-methyladenine have been calculated at the Hartree-Fock level with a 4-21G basis set and are in good agreement with experimental structural data. The ab initio normal modes have been used to interpret experimental ...
We have applied the ab initio path integral molecular dynamics simulation to study hydronium ion and its isotopes, which are the simplest systems for hydrated proton and deuteron. In this simulation, all the rotational and vibrational degrees of freedom are treated fully quantum mechanically, while the potential energies of the ...
Emission spectra of WO have been observed in the 4000-35 000 cm?1 region using a Fourier transform spectrometer. Molecules were produced by exciting a mixture of WCl6 vapor and He in a microwave discharge lamp. A 3?? state has been assigned as the ground state of WO based on a rotational analysis of the observed bands and ab initio calculations. After ...
Results are presented of observations of the vibrational spectrum of Si3C in the Fourier transform IR study of the products of the vaporization of carbon/silicon mixtures trapped in Ar at 13 K. Five of the six fundamental modes are assigned; the assignments are supported by C-13, Si-29, and Si-30 isotopic data and are in excellent agreement with the predictions of an ...
The vibrational spectrum of Ca3Fe2Si3O12 andradite is calculated at the Gamma point by using the periodic ab initio CRYSTAL program that adopts an all-electron Gaussian-type basis set and the B3LYP Hamiltonian. The full set of frequencies (17 IR active, 25 Raman active, and 55 inactive modes) is calculated. The effect of the basis set ...
A pair of peptide groups in space, as modeled by formamide dimer, was used to evaluate vibrational coupling between the amide-I modes and the spatial behavior of the coupling using ab initio quantum chemical calculations. It was found that the coupling between two C=O groups, which is electrostatic in nature, is still quite significant ...
The vibrational spectrum of calcite (CaCO3) is evaluated at an ab initio periodic quantum-mechanical level by using the CRYSTAL package. A localized basis set of Gaussian-type functions and the B3LYP hybrid Hamiltonian are adopted. The dynamical matrix is obtained by differentiating numerically the analytical first derivatives of the ...
The structures, interaction energies and vibrational spectra of the electron donor-acceptor complexes formed between boron trifluoride, as Lewis acid, and methanol and methanethiol, as Lewis bases, have been determined by means of ab initio calculations at the level of second order M�ller Plesset perturbation theory, using a ...
We report a full dimensional, ab initio-based global potential energy surface (PES) and dipole moment surface for Cl-H2O. Both surfaces are symmetric with respect to interchange of the H atoms. The PES is a fit to thousands of electronic energies calculated using the coupled-cluster method [CCSD(T)] with a moderately large basis (aug-cc-pVTZ). ...
We computed the Raman spectrum of amorphous GeTe by ab initio simulations and empirical bond polarizability models. The calculated spectrum is in very good agreement with experimental data and contains the signatures of all the peculiar local structures of the amorphous phase revealed by recent ab initio ...
Hydrogen arranges at dislocations in palladium to form nanoscale hydrides, changing the vibrational spectra. An ab initio hydrogen potential energy model versus Pd neighbor distances allows us to predict the vibrational excitations for H from absolute zero up to room temperature adjacent to a partial dislocation ...
Raman spectra of binary sodium silicates are calculated by self-consistent field (SCF) molecular orbital ab initio calculation of the quantum chemical method with several poly silicon-oxygen tetrahedral model clusters when both the basis sets of 6-31 G and 6-31 G(d) are applied. The symmetric stretching vibrational frequency of ...
A new global potential energy surface for the lowest triplet electronic state (a3A'') of HNO has been developed by a three-dimensional cubic spline interpolation of more than 13 000 ab initio points, which were calculated at the multireference configuration interaction level with Davidson correction using the augmented correlation-consistent polarized ...
A new global potential energy surface for the lowest triplet electronic state (a(3)A") of HNO has been developed by a three-dimensional cubic spline interpolation of more than 13,000 ab initio points, which were calculated at the multireference configuration interaction level with Davidson correction using the augmented correlation-consistent polarized ...
We study the relation between the hydrogen bonding and the vibrational frequency spectra of water on the (110) surface of rutile ({alpha}-TiO{sub 2}) with three structural layers of adsorbed water. Using ab initio molecular dynamics simulations at 280, 300, and 320 K, we find strong, crystallographically controlled adsorption sites, in ...
We study the relation between hydrogen bonding and the vibrational frequency spectra of water on the (110) surface of rutile (α-TiO2) with three structural layers of adsorbed water. Using ab-initio molecular dynamics simulations at 280, 300 and 320K, we find strong, crystallographically-controlled adsorption sites, in general agreement with ...
The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed ...
The geometries and vibrational frequencies of Se{sub n} clusters (n=2-8) are calculated using ab initio molecular orbital theory at various levels of approximation. The computed vibrational frequencies are in satisfactory agreement with the available experimental data on matrix isolated clusters and have small ...
Anharmonic vibrational frequencies and intensities are calculated for 1:1 and 2:2 (HCl)(sub n)(NH3)(sub n) and (HCl)(sub n)(H2O)(sub n) complexes, employing the correlation-corrected vibrational self-consistent field method with ab initio potential surfac...
We present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a Grueneisen equation of state and a quasiharmonic approximation to the vibrational energies, we derive a simple, post-processing method for calculation of the quantum corrected Hugoniot ...
We present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a Griineisen equation of state and a quasi-harmonic approximation to the vibrational energies, we derive a simple, post-processing method for calculation of the quantum corrected Hugoniot ...
Fourier transform vibrational circular dichroism (FT-VCD) spectra of the small pharmaceutical molecules propanolol, ibuprofen and naproxen have been measured in the hydrogen stretching and mid-infrared regions to obtain information on solution conformation and to identify markers for absolute configuration determination. Ab initio ...
Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 mum and 10.6 mum regions of CO_2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low resolution IR spectra. The ab ...
The ?4 fundamental vibration spectrum of the weakly bound complex Ar-CH4 in the 7?m region was discovered, analyzed, and compared with a synthesized spectrum, derived from ab initio calculations. The measurements were made by probing a supersonic gas expansion with a tunable diode laser (TDL) spectrometer. Several bands of Ar-CH4 ...
... ADP012740 TITLE: Ab Initio Study on Spin Polarization of III-V Compound Tips ... Ab initio study on spin polarization of III-V compound tips ...
...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...
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