... eg, SiHl6= has a negative ionization potential. ... V. POTENTIAL ENERGY SURFACES AND DYNAMICS ... initio with effective core potentials, ab initio ...
DTIC Science & Technology
... goals of this program have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...
... Abstract : This final technical report summarizes research on application of ab initio quantum chemical techniques to enzyme inhibitors such as ...
... Abstract : Contents: Ab-initio quantum chemical investigations of the mechanism of cationic polymerization; Development of theoretical procedures ...
... index to significant articles, news items, and ... Author : INSTITUTE OF THEORETICAL PHYSICS AND ASTRONOMY VILNIUS (LITHUANIA). ...
This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and electrostatic molecular potential contour maps for cationic polymerization; Prediction of crystal density;...
National Technical Information Service (NTIS)
In this paper we review the existing theoretical literature on hydrogen storage in single-walled carbon nanotubes. The importance of theoretical simulations for understanding the adsorption procedure and for improving the storage capacity of these nano-materials is underlined. We report two different categories of theoretical approach ...
NASA Astrophysics Data System (ADS)
Ab initio calculations have been carried out on the first- and second-row transition-metal mono- and
NASA Technical Reports Server (NTRS)
... goals of this program have been to develop new, more effective methods for perform in accurate ab initio electronic structure calculations and to ...
... Abstract : Ab initio quantum chemical simulations were coupled with variational transition state theory in estimating rate constants for the H + C3H3 ...
... Andrew Ichimura Ph. ... AS Ichimura, A. R. Matlin, PM Lahti, "An Ab Initio Study of Methano and Ethano Bridged Derivatives of Oxyallyl.", J. Am. Chem. ...
... Andrew Ichimura Ph. ... AS Ichimura, AR Matlin, PM Lahti, "An Ab Initio Study of Methano and Ethano Bridged Derivatives of Oxyallyl.", J. Am. Chem. ...
materials, (iiii) phonon recycling in lasers, and (iv) phonon-assisted photon absorption in photovoltaics. The theoretical treatments include ab initio and molecular dynamic...
Science.gov Websites
... This is being done by carrying out theoretical high quality three-dimensional ab-initio quantum chemical calculations on the oximes and from these ...
... 31,37,38). A recent theoretical ab initio quantum mechanics study predicts that the cysteinyl-FMN adduct may ... ...
NBII National Biological Information Infrastructure
... substantial impact; these tools are now incorporated in many ab initio codes ... Most commonly used quantum chemical methods possess one or the ...
An ab initio calculation is needed to obtain a more reliable theoretical estimate. .... piezoelectric properties of [II-V semiconductors ...
NASA Website
The objective of this research was to investigate fundamental aspects of the fracture and deformation behavior of ordered intermetallic aerospace alloys on the basis of the ab-initio determination of the parameters needed for further (1) model theoretical...
piezoelectric parts. The spontaneous part is modeled with an ab initio result of a theoretical calculation, while the piezoelectric ...
Aug 17, 2010 ... Theoretical cross sections for the pressure broadening by hydrogen of rotational transitions of water are compared to the latest available ...
... Abstract : Electronic structure calculations using theoretical methods based on the linked-diagram theorem are reported for a series of dissociation ...
... previous grant period have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to ...
Using a theoretical quantum chemical approach, we .... completion of the ab initio calculation of the Rydberg and valence potential ...
Ab-initio quantum chemical investigations of the mechanism of cationic polymerization; Development, implementation testing of theoretical procedures for prediction of crystal structures and densities; Ab-initio quantum chemical MODPOT/VRDDO/MERGE calculat...
Contents: Ab-initio quantum chemical investigations of the mechanism of cationic polymerization; Development of theoretical procedures for prediction of crystal structures and densities; Ab-initio quantum chemical MODPOT/VRDDO/MERGE calculations on nitro-...
This research concerned the development of new ab initio nonempirical quantum-theoretical methods and computational techniques for studying molecular properties related to those of advanced materials. Extensive computations were performed to demonstrate t...
The oxidation of the trichlorooxyphosphorus anion (POCl3(-)), which takes place in combustion flames, has been examined experimentally at a variety of temperatures and theoretically via ab initio and density functional methods. The reaction was examined i...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
The rotational mechanism of the NH{sub 4}{sup +} ion in water is analyzed by using both semiempirical (AM1) and ab initio (6-31G* SCF level) methods. AM1 predicts rapid rotation at any degree of first solvent shell hydration from n = 1-6. These results are considered artifactual since AM1 favors ion-water structures of a type not found in ...
Energy Citations Database
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 previous ab initio results on lattices of K atoms for coordination numbers z 8, 4, and 2 are analyzed these DFT results for K into contact with a simple and physically appealing quantum-chemical model proposed conclusions are given at the end of the paper. II. THEORETICAL METHOD We have performed the ab ...
E-print Network
The electric dipole transition moment has been cancelled a priori for the electronic transition as a function of R(C-C), using ab initio quantum chemical techniques including state averaged, complete active space MCSCF and multireference CI. The transitio...
We present a theoretical investigation of the electronic structure of an InAs monomolecular plane inserted in bulk GaAs. Our calculations are based on the ab initio self-consistent pseudopotential method. Both electrons and holes are found to be strongly ...
Ab-initio calculations within the DFT and GGA have been carried out in an attempt to understand better which property sets the activity of transition metal sulfides (TMS) in the hydro-desulfurization reaction (HDS), a most important step in the refining o...
The potential barriers for the internal rotation of silole dimers are studied theoretically using the ab initio molecular orbital method at the RHF/6-31G** level of calculations. In 2,2{prime}-bisilole, it is found that the anti-conformation is the most stable structure in the ground state and that the potential barrier height for ...
There has been an interest in the study of hydrogen ion clusters. However, only positive clusters, Hn +, where n = 3m 5, 7, ..., have been discovered and successfully analyzed by meand of both experimental and ab initio theoretical methods (cf. Hirao and ...
High-level quantum-chemical ab initio coupled-cluster and multiconfigurational perturbation methods have been used to compute the vertical and adiabatic electron affinities of the five canonical DNA and RNA nucleobases: uracil, thymine, cytosine, adenine, and guanine. The present results aim for the accurate determination of the intrinsic electron acceptor ...
... 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,. ...
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 ...
UTChem is a quantum chemistry software developed by Hirao's group at the University of Tokyo. UTChem is a research product of our work to develop new and better theoretical methods in quantum chemistry.
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 figs.
DOE Information Bridge
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...
A theoretical model of Thomson scattering in a magnetized plasma, taking spatial dispersion into account, is developed ab initio. The resulting expressions allow thermal motion to be included in the description of the plasma and remain valid for frequenci...
Hydrozirconization of acetylene and ethylene was studied for Cp{sub 2}Zr(H)Cl. The study was based on ab initio MO theory calculations. Hydrozirconation by Cl{sub 3}ZrH was presented for comparison with the Cp analog.
The structure of atomic clusters is investigated using methods of ab initio quantum chemistry in conjunction with scanning tunneling microscopy (STM). Gold sols are imaged via STM and their sizes characterized. Atomic resolution reveals facets, steps, and...
Ab initio (MP2/6-31G**//MP2/3-21G) calculations yield a value of about 729 kJ/ mole, ... Quantum chemical; Lubricants; Modelling; Semiempirical; Lubrication; ...
... Abstract : Using ab initio (6-31G(*)) and semiempirical (AM1, PM3) electronic structure calculations and force field (MM3) determinations, we have ...
The main goals of this program have been to develop new, more effective methods for perform in accurate ab initio electronic structure calculations and to use these methods for the prediction of molecular structure, bonding and reactivity, especially for ...
The main goals of this program have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to use these methods for the prediction of molecular structure, bonding and reactivity, especially for ...
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...
The reaction of methyl radicals with hydrogen atoms is studied with a combination of ab initio quantum chemistry, variational transition state theory, and classical trajectory simulations. The interaction between the two radicals, including the umbrella m...
We develop and apply an ab-initio approach to nuclear structure. Starting with the NN interaction, that fits two-body scattering and bound state data, and adding a theoretical NNN potential, we evaluate nuclear properties in a no-core approach. For presen...
This final technical report summarizes research on application of ab initio quantum chemical techniques to enzyme inhibitors such as acetylcholinesterase. Computational techniques have been developed, tested and applied to (1) chemically related series of...
A theoretical research investigation of materials that are potential additives for solid hydrogen rocket fuels is investigated. The ab initio calculations show that mixed clusters of boron and lithium prefer to have an electronegative boron atom at the mi...
elucidate the properties of these molecular systems. Alkali-doped buckminsterfullerene(A$@) has been shownto
Theoretical heats of formation at 298 K for several alkylsilanes, predicted at the MP2/6-31G(d) level of theory, are compared with recently obtained experimental and additivity values. Excellent agreement is obtained between the ab initio and additivity v...
The study of phase stability, including order-disorder phenomena and structural transformations, in substitutional alloys is of great theoretical and technological interest. The goal is to perform ab-initio calculations of thermodynamical properties of al...
We present a combined experimental and theoretical study on carbon nanodiamonds using Raman and DAC experimentation and ab initio calculations. Our calculations confirm the surface reconstruction to a fullerene-like structure, and indicate compression of ...
We present a combined experimental and theoretical study on carbon nanodiamonds (NDs) using Raman and DAC experimentation and ab initio calculations. Our calculations confirm the surface reconstruction to a fullerene-like structure, and indicate compressi...
Powder diffraction has developed into an important crystallographic tool over the past thirty years largely because of the success of the Rietveld profile method in structure refinement. The improvements in instrumentation in this period have led to the s...
Ab initio quantum chemical calculations are presented for the energy of dimerization of the borane molecule (2BH3 B2H6). The calculations are superior to previous theoretical treatments both in the level of treatment of electron correlation and in the one...
Density Functional Theory (DFT) is one of the most used {\\em ab initio} theoretical frameworks in materials science. It derives the ground state properties of multi-atomic ensembles directly from the computation of their one-particle density \
We compare ab initio broad spectrum calculations of the K-edge X-ray absorption spectra of copper and molybdenum against accurate experimental measurements and tabulated standards on an absolute scale. Comparisons are also presented for the fine structure in the spectra.
A simple procedure is described for estimating the effective errors in molecular energies calculated by ab initio methods with respect to use of the latter in studies of chemical reactions. The procedure is illustrated by application to the STO-3G, 3-21G,...
The catalytic properties of cobalt oxide (Co0) were investigated theoretically. The interactions of atomic hydrogen with small clusters of atoms, representing cobalt oxide surfaces, were calculated using the ab initio Unrestricted Hartree-Fock (UHF) metho...
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...
This report results from a contract tasking Institute of Theoretical Physics and Astronomy as follows: The contractor will investigate quantum mechanical design of light-driven, single supermolecular logically-controlled machines and molecular computing d...
The main goals in the previous grant period have been to develop new, more effective methods for performing accurate ab initio electronic structure calculations and to use these methods for the prediction of molecular structure, bonding and reactivity, es...
In this work we present a theoretical and experimental study of the acetylene-hydrogen system. An ab initio potential surface has been obtained by ab initio quantum chemistry methods. This 4-dimensional potential is further used to compute pressure broadening coefficients of C2H2 isotropic ...
... 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
Ab initio Hartree--Fock calculations were performed on FeAr and FeAr/sup +/ in order to determine the interaction of both neutral and singly-ionized Fe atoms trapped in Ar, and on ArFeCO and FeCOAr in order to ascertain the effect of an Ar matrix on the FeCO molecule. Quadrupole splittings and isomer shifts are computed using ab ...
We review the recent research on the functional mechanisms of biological macromolecules using theoretical methodologies coupled to ab initio quantum mechanical (QM) treatments of reaction centers in proteins and nucleic acids. Since in most cases such biological molecules are large, the computational costs of performing ...
PubMed
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 ...
Structure and dynamics of HeI2 van der Waals (vdW) complex are analyzed from first principles. Ab initio technology, at CCSD(T) and MRCI level of theories, was employed for constructing potential energy surfaces of the ground and excited electronic states, and a full quantum mechanical treatment for studying its dynamics was applied. Spectroscopy in the ...
The ability of simple levels of ab initio molecular orbital theory to describe with reasonable accuracy the energetics of isotopic exchange processes is demonstrated. Three levels of ab initio molecular orbital theory have been surveyed. The first two levels are single-determinant Hartree-Foch methods utilizing the ...
Solid State Nuclear Magnetic Resonance (NMR) is a powerful tool in crystallography when combined with theoretical predictions. So far, empirical calculations of spectra have been employed for an unambiguous identification. However, many complex systems are outside the scope of these methods. Our implementation of ultrasoft and projector augmented wave pseudopotentials within ...
An ab initio study based on local-density-functional (LDF) theory is presented for the chemisorption of hydrogen on the Pd(111) surface. Our calculation uses the Vienna ab initio molecular-dynamics program (VAMP) based on (i) finite-temperature LDF, (ii) exact calculation of the electronic ground state and ...
The methodology of ab initio molecular dynamics, wherein finite-temperature dynamical trajectories are generated by using forces computed "on the fly" from electronic structure calculations, has had a profound influence in modern theoretical research. Ab initio molecular dynamics allows ...
The methodology of ab initio molecular dynamics, wherein finite-temperature dynamical trajectories are generated by using forces computed �on the fly� from electronic structure calculations, has had a profound influence in modern theoretical research. Ab initio molecular dynamics allows ...
PubMed Central
The structural, electronic and dynamic properties of cesium chloride, ZrRu and ZrZn were studied by employing an ab initio pseudopotential method and a linear response scheme, within the generalized gradient approximation. The calculated lattice constant, bulk modulus and first-order pressure derivative of the bulk modulus were reported in B2 structure and ...
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 respective atomic ...
Theoretical Insight into the Interactions of TMA-Benzene and TMA-Pyrrole with B3LYP Density theoretical investigation of the tetramethylammonium(TMA)-benzene and TMA-pyrrole complexes has been performed density in the 5 6 aromatic system of pyrrole is larger than that in the 6 6 system of benzene
By means of solid-state linear-dichroic infrared (IR-LD) spectroscopy the stereo-structures of dipeptides methionyl-histidine (Met-His) and histidyl-methionine (His-Met) are predicted, accompanied with a detailed experimental IR-characteristic bands assignment. The experimental results are compared and confirmed with theoretical structural ones, obtained by ...
Ab initio band structure calculations have been performed for the spin-orbit interaction effects at the top of the valence bands for GaAs and InSb. Relativistic, norm-conserving pseudopotentials are used with no correction made for the gaps from the local density approximation. The spin-orbit splitting at GAMMA and linear terms in the /rvec char/k ...
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 energy calculations. Our ...
The authors present a newly developed, ab-initio, self-consistent procedure for predictive calculations of electronic and related properties of ferroelectric materials. Known as the Bagayoko, Zhao, and Williams (BZW) procedure, this approach resolves the long-standing disagreement between experimental and theoretical conduction bands, in general, and band ...
Experimental single-molecule stretching curves for three backbone architectures (single-stranded DNA, various types of peptides, polyvinylamine) are quantitatively compared with corresponding quantum-chemical (zero-temperature) ab-initio calculations in the high-force range of up to two nanonewtons. For high forces, quantitative agreement is obtained with the contour length of ...
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 ...
A new ab initio potential energy surface of the Ne�CO complex is developed using single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD(T)]. The potential has a minimum value of ?49.396 cm?1 at Re = 6.40a0 with approximately T-shaped geometry (?e = 82.5�). Bound state energies are calculated up to J ...
The total energy of a grain boundary in a transition metal is calculated in an {ital ab} {ital initio} manner. Such calculations are now feasible using a plane-wave basis set provided that an optimally convergent pseudopotential is used. The investigation focuses on resolving two competing atomic models for the {Sigma}=5 (001) twist boundary in gold. It is ...
This paper presents results obtained in ab initio calculations of the thermodynamic properties of B1 and B2 lithium fluoride under pressure. The data were used to calculate LiF isotherms and isochors at pressures from 0 to 500 GPa and temperatures up to the melting point. Calculated results are compared with available theoretical and ...
Ab initio theoretical investigations of the dynamics and thermodynamics of a compressed Ne crystal performed using a model that explicitly takes account of the deformation of the electronic shells in the dipole approximation are presented. A dynamical matrix based on a non-empirical short-range repulsive potential and integration over ...
In the present work we report the results of ab initio studies of electronic and dynamic properties of nickel based Heusler alloy Ni2MnAl. The total magnetic moment and elastic constants were also evaluated and compared to experimental results where possible. We found that the phonon dispersion relations calculated in this work within the linear response ...
The desorption potential energies of a hydrogen molecule from hydrogenated diamond C(100) surfaces have been calculated by the ab initio pseudopotential method.We found that a dihydride surface is less stable than a monohydride surface and that hydrogen desorption can be expected to occur from the dihydride instead of the monohydride phase of a C(100) ...
Following atomic photoionization, the abrupt change in potential can lead to secondary ionization of an outer-shell electron in a phenomenon known as shake-off, a process which gives rise to the asymmetric K? profile and satellite lines. Investigation of chemical effects and relativistic quantum mechanics requires a theoretical determination of these satellite intensities; ...
... 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
Theoretical studies supporting the Livermore photolytic Group VIA laser project were initiated early in 1977. Results of numerous theoretical studies which deal with the photolysis process, losses in the upper laser level and the photolytic pumps are described. Results of ab initio calculations on OCS have been ...
A new method of incorporating ab initio theoretical data dynamically into the gas-phase electron diffraction (GED) refinement process has been developed to aid the structure determination of large, sterically crowded molecules. This process involves calculating a set of differences between parameters that define the positions of ...
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 frequencies are scaled using ...
The theoretical principles underpinning the calculation of infrared spectra for condensed-phase systems in the context of ab initio molecular dynamics have been recently developed in literature. At present, most ab initio molecular dynamics calculations are restricted to relatively small ...
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 ...
The study of materials properties under extreme conditions has made considerable progress over the past decade due to both improvements in experimental techniques and advanced modeling methods. The availability of accurate models is crucial in order to analyze experimental results obtained in extreme conditions of pressure and temperature where experimental data can be scarce. Among ...
... ADP023770. Title : ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper. ...
... Ab initio Energies Calculated Using 3 ... of the Transition States (TS ... Descriptors : *TRANSITIONS, *MOLECULES, COMPUTATIONS, COMPARISON ...
... Title : Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper (preprint). ...
... 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. ...
... Accession Number : ADA270577. Title : Ab Initio Potential Energy Surface for the H + OCS Reaction. Descriptive Note : Final rept. ...
... Ab initio direct trajectory simulation on hydrogen atom transfer in 7-azaindole in the electronic excited state with assist of water molecules ...
... Title : Ab Initio Calculation of Vibrational Circular Dichroism Spectra Using Accurate Post-Self-Consistent-Field Force Fields: trans-2,3 ...
