The results of ab initio multi-configuration self-consistent field (MSCF) calculations on 1,2-cyclohexadiene are reported. These calculations support the contention that the compound's equilibrium geometry is strongly bent and chiral but can easily racemize. Structures are proposed for the ground state, diradical, and ...
Energy Citations Database
Multiconfiguration relativistic Dirac-Fock calculations of KLL Auger energies are reported for neon, argon, uranium, and americium. These selected examples demonstrate the feasibility of this method to calculate completely ab initio, in intermediate coupling, Auger transition energies with a precision of a few eV. Comparison of our ...
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; however, existing ...
NASA Astrophysics Data System (ADS)
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 ...
Realistic electronic-structure calculations for correlated Mott insulators are notoriously difficult. Here we present an ab initio multiconfiguration scheme that adequately describes strong correlation effects involving Cu 3d and O 2p electrons in layered cuprates. In particular, the O 2p states giving rise to the Zhang-Rice band are ...
The broad goal of our research program was to study excited state chemistry, and electronic energy transfer and chemical energy redistribution processes, using the methods of ab initio electronic structure theory. Over the period of this grant we have stu...
National Technical Information Service (NTIS)
Our program concerns the theoretical investigations of the dynamic effects of relativity and electron correlations on atomic processes, and the developments of relativistic many-body techniques for atomic structure calculations. Currently, we are studying atomic hyperfine structures (hfs) with the multiconfiguration Dirac-Fock (MCDF) technique. This is a very general ...
DOE Information Bridge
The multiconfigurational CASSCF/CASPT2 approach, along with various functionals of density functional theory, is applied to selected iron(II)-nitrosyl ({FeNO}(7)) complexes, both with heme and nonheme groups. The energetics of the lowest doublet and quartet spin states at the correlated ab initio (CASPT2) level is presented for the ...
PubMed
The scattering length for electron-argon scattering is calculated very accurately by an [ital ab] [ital initio] method with wave functions computed exactly at zero energy. The multiconfiguration Hartree-Fock method, which takes into account the effects of target polarization and electron correlation through the ...
Ab initio calculations at the multiconfiguration self-consistent field level followed by a multireference configuration interaction were carried out along the two possible collinear approaches of the [LiHHe]+ system, while a three-dimensional calculation of the structures of that complex with LiH+ kept at its equilibrium geometry was ...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
DTIC Science & Technology
Nonrelativistic and quasirelativistic energy-adjusted ab initio pseudopotentials are presented for element 105 (hahnium, Ha) together with corresponding energy-optimized valence basis sets. The method of energy adjustment of pseudopotentials is extended to a two-component formalism and to multiconfiguration wave functions. The accuracy ...
This commentary focuses on the conceptual interpretation of the bonding of O(2) and NO to heme in oxyheme and nitrosylheme complexes, using high-level ab initio complete active space self-consistent field (CASSCF)/molecular mechanical (MM), gas-phase CASSCF, and CASSCF followed by second-order perturbation theory (CASPT2) calculations as well as density ...
The atomic-beam laser-rf double-resonance method has been used to measure precisely the dipole and quadrupole hyperfine structure (hfs) of 11 levels of the 5d/sup 2/6s configuration and four levels of the 5d/sup 3/ configuration of /sup 139/La I. The results, together with earlier results for lower-lying levels, are compared in detail with new multiconfiguration Dirac-Fock ...
The aromatic excimers of benzene, naphthalene, anthracene, pyrene, and perylene are systematically investigated using the multiconfiguration quasi-degenerate perturbation theory (MCQDPT) method, which is one of high-level ab initio quantum chemical methods. The reference configuration space for MCQDPT is carefully designed for an ...
A fewest switches trajectory surface hopping algorithm based on linear response time-dependent density-functional theory is developed and implemented into the plane wave ab initio molecular dynamics package CPMD. A scheme to calculate nonadiabatic couplings using a multi determinantal approximation of the excited state wave function is introduced. The ...
The electronic structure of the model compounds U(NH{sub 2}){sub 3} and Np(NH{sub 2}){sub 3} is investigated with the aid of ab initio electronic structure techniques. The electronic ground states and equilibrium geometries of these complexes are determined using multi-configuration SCF techniques. Comparisons are made to their ...
The importance of relativistic effects on chemical and spectroscopic properties of molecules containing very heavy atoms is considered. Recent developments that combine large scale ab initio multiconfiguration self-consistent field/configuration interaction (MCSCF/CI) methods with relativistic configuration interaction (RCI) methods ...
Ab initio molecular orbital studies that include variational (with a multiconfiguration reference state of 200 states) and perturbational (including over 3 million configurations) configuration interaction calculations were addressed to the interaction of nitrogen molecules with copper. The Cu ground state {sup 2}S and first two ...
In this paper we report a theoretical study of the static dipole polarizability of two one-dimensional structures: (a) linear carbon chains Cn (n=2-10) and (b) ladderlike planar boron chains Bn (n=4-14). The polarizabilities of these chains are calculated both at the Hartree-Fock and the correlated levels by applying accurate ab initio quantum-chemical ...
... 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,. ...
The multiconfiguration Hartree-Fock method has been applied to study low-energy scattering of electrons from argon atoms. The polarization of the argon atoms due to the scattered electron and the electron-correlation effects that are very important in the calculation are taken into account in the {ital ab} {ital nitio} way more accurately through the ...
... 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
NASA Technical Reports Server (NTRS)
A detailed analysis of the value of zero-field splitting for the di- and trivalent chromium hexaquo complexes is presented. The effect of the Jahn-Teller distortion was studied, for the case of the divalent complex, through the use of state-averaged CASSCF calculations, for the mapping of the potential energy surface along the e(g) normal modes. At the minima of the surface, ...
The following topics are contained in this volume: how can materials theory benefit from supercomputers and vice-versa; the materials of xerography; relationship between ab initio and semiempirical theories of electronic structure and renormalization group and the statistical mechanics of polymer systems; ab initio ...
The SC3 H radical is known by experiment to have a linear equilibrium structure, but even rather high-level ab initio computations give a bent equilibrium geometry. A theoretical study of the SCCCH radical has been carried out in order to analyse the influence of several factors in the computed equilibrium structure. Quadratic configuration interaction ...
The short-time photodynamics (1 ps) of formamide in its low-lying singlet excited n(O)-pi(*) and pi-pi(*) states have been investigated by the direct trajectory surface-hopping method based on multiconfigurational ab initio calculations. The simulations showed that in both states, the primary deactivation process is C-N bond ...
The short-time photodynamics (1 ps) of formamide in its low-lying singlet excited nO-?* and ?-?* states have been investigated by the direct trajectory surface-hopping method based on multiconfigurational ab initio calculations. The simulations showed that in both states, the primary deactivation process is C-N bond dissociation. In ...
A new implementation of nonadiabatic excited-state dynamics using hybrid methods is presented. The current approach is aimed at the simulation of photoexcited molecules in solution. The chromophore is treated at the ab initio level, and its interaction with the solvent is approximated by point charges within the electrostatic embedding approach and by a ...
Isotope fractionation in the U(III)-U(IV) reaction system was investigated by a series of atomic relativistic ab initio calculations using the multiconfigurational Dirac-Coulomb Hartree-Fock method. To evaluate the nuclear volume effect on the fractionation, the Fermi statistical distribution function was adopted for nuclear charge ...
Intermolecular potentials for the three lowest multiplet states (singlet, triplet and quintet) of the O2(3Sigma)-O2(3Sigma) dimer have been investigated in detail by means of high level ab initio calculations. The methods used include MRCI, ACPF, CASPT2, using different active spaces and basis sets. The results for the quintet state are compared with ...
In this work, we report on our full results of the spectroscopic analysis of the quasi-linear S2 state of the prototypical halocarbene, CHF, and its deuterated isotopomer CDF using optical-optical double resonance spectroscopy through the S1 state. A total of 51 S2 state vibrational levels with angular momenta in the range l = 0-3 were observed for CHF, and 76 levels for CDF. Progressions ...
Multiconfiguration self-consistent-field calculations have been carried out on the X /sup 1/S/sup +/ and a /sup 3/S/sup +/ states of LiH, NaH, KH, RbH, and CsH, and on the X /sup 2/S/sup +/ states of their respective anions. Pseudopotentials, including core polarization terms, have been used to replace the core electrons, resulting in simple two- and three-electron ...
Relativistic pseudopotentials (PPs) of the energy-consistent variety have been generated for the post-d group 13-15 elements, by adjustment to multiconfiguration Dirac-Hartree-Fock data based on the Dirac-Coulomb-Breit Hamiltonian. The outer-core (n-1)spd shells are explicitly treated together with the nsp valence shell, with these PPs, and the implications of the small-core ...
The development of fusion reactors has generated a demand for improved knowledge of the atomic properties of tungsten. Using a multi-configuration Dirac�Fock (MCDF) method with a restricted active space treatment, the wavelengths and transition probabilities of the M1 and E2 transitions in the visible light region are calculated for the ground state multiplets of W26 + ions. ...
Energy levels and radiative transition probabilities have been calculated for states within the 6pk (k = 1-5) configurations in the thallium, lead, bismuth, polonium and actinium sequences up to radon. Magnetic dipole (M1) and electric quadrupole (E2) transition probabilities have been obtained using average energies, electrostatic and spin-orbit integrals adjusted so as to fit the observed energy ...
The application of computational chemistry in resolving photochemical and photobiological problems depends on theoretical models and calculation strategies that allow an understanding of how and when the energy contained in a photon can be used or dissipated by a molecule. Progress in this arena has been the result of a scientific journey that can be traced from the 1960s and 1970s with the ...
This work is an ab initio study of the 2p34S3/2o, and 2D3/2,5/2o states of C- and 2p23P0,1,2, 1D2, and 1S0 states of neutral carbon. We use the multiconfiguration Hartree-Fock approach, focusing on the accuracy of the wave function itself. We obtain all C- detachment thresholds, including correlation effects to about 0.5%. Isotope ...
Ab initio Hartee--Fock (HF) and multiconfiguration Hartee--Fock (MCHF) calculations have been carried out to characterize the reactants, transition state, and products of the electrophilic addition of O(/sup 3/P) to the ..pi.. bond of ethylene. The results show that the diradical product CH/sub 2/CH/sub 2/O is stable with respect to ...
Gas-phase absorption properties of chromophores of several photoactive proteins have been studied experimentally at the electrostatic heavy-ion storage ring ELISA in Aarhus. The absorption wavelength has been calculated using an augmented effective Hamiltonian technique based on the multiconfigurational quasi-degenerate perturbation theory. The results have been compared to ...
The potassium trimer is investigated in its lowest electronic doublet states, employing several high-level ab initio methods (coupled cluster with single, double, and noniterative triple excitations, multiconfiguration self-consistent field, and multireference Rayleigh-Schr�dinger perturbation theory of second order). One-dimensional ...
Collinear laser--ion-beam spectroscopy has been used to measure hyperfine structure (hfs) in three levels of the 3d/sup 2/ and six levels of the 3d4p configuration of Sc II. The results combine with earlier measurements of hfs within these configurations to give a fairly complete picture of hfs in these configurations. The combined results are compared with multiconfiguration ...
Electronic circular dichroism (ECD) parameters of the disulphide chromophore have been calculated for dihydrogen disulphide, dimethyl disulphide, and cystine using density-functional theory, coupled-cluster theory, and multiconfigurational self-consistent field theory. The objective is twofold: first, to examine the performance of the Coulomb-attenuated CAM-B3LYP functional ...
We report on large ab initio calculation for the 4s^2- 4s4p transitions in the Zinc-like sequence, using the multi-configuration Dirac-Hartree-Fock method. Results for fine-structure energy levels, the wavelengths, transition rates and lifetimes between Z = 70 (Yb) and Z= 92 (U) are presented and compared with other theories and ...
In concert with the latest experiment of velocity imaging technique [X. P. Zhang et al., ChemPhysChem 9, 1130 (2008)], quantum chemical calculations with relativistic effect were performed on the photodissociation of bromobenzene (BrPh) and iodobenzene (IPh) at 266 nm. The method of multistate second order multiconfigurational perturbation theory in conjunction with spin-orbit ...
We present highly correlated multi-configuration Hartree�Fock (MCHF) calculations of the hyperfine structure of the 3p5 2PoJ levels of 33S? and 35, 37Cl. We obtain good agreement with observation. The hyperfine structure of the neutral sulphur 33S 3p4 3PJ lowest multiplet that has never been measured to the knowledge of the authors is also estimated theoretically. We discuss ...
... 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
... 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 ...
The electronic structure of the ScN and ScP molecules is a subject of controversy and turns out to be a challenging problem in quantum chemistry. We show that the ground-state electronic structure for both molecules depends critically on the choice of methods used which incorporate different ways of accounting for electron correlation. A parallel ab ...
We report on the determination of a high quality ab initiu potential energy surface (PES) and dipole
The spin distribution of the neutral soliton in {ital trans}-polyacetylene is controversial, as evidenced by the markedly different interpretations given by the various active experimental groups to their ENDOR measurements of proton hyperfine coupling (hfc) constants. To help resolve the discrepancies, {ital ab} {ital initio} electronic structure ...
A theoretical model is presented for deriving effective diabatic states based on ab initio self-consistent field valence bond (VBSCF) theory by reducing the multi-configurational VB Hamiltonian into an effective two-state model. We describe two computational approaches for the optimization of the effective diabatic configurations, ...
PubMed Central
Ab initio quantum chemical strategies for quantitatively predicting the lowest (1Ag rarr 1T1g) vertical d-d excitation energy of hexaammineruthenium(II) ion in aqueous solution are discussed. The scalar-relativistic ECP/valence basis set on Ru atom developed by the Stuttgart group in a combination with the state-average CASSCF(d) approach, followed by ...
This paper discusses the nuclear volume dependence of uranium isotope fractionations in the U3+-U4+ and U4+-UO22+ systems by reference to a series of ab initio molecular orbital calculations. Nuclear volume-dependent terms (?ln Knv) in isotope fractionation coefficients (??) are calculated from the energetic balance of the isotopomers involved in the ...
