... Title : Ab Initio Calculation of Vibrational Circular Dichroism Spectra Using Accurate Post-Self-Consistent-Field Force Fields: trans-2,3 ...
DTIC Science & Technology
... furnished keywords include: nitroaromatic; nucleophilic attack; electrostatic potential; nitrobenzene; ab initio self-consistent-field calculations; and ...
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...
National Technical Information Service (NTIS)
The addition and abstraction reaction pathways on the potential energy surface for H + HCO have been characterized by an ab initio four electron, complete active space, self-consistent field electronic structure calculation. The elimination pathway to go ...
The electronic structure of a vacancy in Al was calculated self-consistently using norm-conserving ionic pseudopotentials obtained from ab initio atomic calculations. A 27-atom-site supercell containing 1 vacancy and 26 atoms was used to simulate the envi...
This report briefly summarizes the research developments in ab initio dynamics made possible by this augmentation award to the parent ONR grant. A full description of the research accomplishments will appear in the final technical report of the parent gra...
The relaxations of hydrogenated Silicon and Germanium (111) surfaces are determined using ab initio self consistent calculations in a slab configuration. The Si-hydrogen and Ge-H bonds are found to be considerably larger than the sum of covalent radii. Th...
The dipole moment and hyperfine constants of OD (and OH) A2?+ have been obtained from ab initio calculations, using self-consistent field and configuration ...
NASA Website
A computational study of 48 nitroaromatic molecules has been carried out with the objective of developing an understanding of how chemical structural features are related to the shock/impact sensitivities of these molecules. An ab initio self-consistent-f...
... MgPc) and its radical anion doublet (MgPc-), using both ab-initio (6-13G**) and semiemperical (INDO/1) self-consistent field approaches. ...
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
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...
Ab-initio study of zone centre phonons in rare-earth hexaborides, MB6, has been made using self-consistent density functional method based on norm-conserving pseudo-potentials and numerical atomic orbitals as basis set. Calculated values of zone centre phonons are in fair agreement with the experimental results.
NASA Astrophysics Data System (ADS)
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 ...
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 ...
We report an {ital ab initio} evaluation of the surface energy of a simple metal, performed via a coupling-constant integration over the dynamical density-response function. The rapid rate of change of the electron density at the surface is treated exactly. Long-range correlations are treated self-consistently in the random-phase ...
The theoretical foundations and the implementation of a computer program for generalized self-consistent field (GSCRF) calculations are described. The GSCRF model takes the microscopic structure of the environment of a solute explicitly into account; it models electrostatic interaction between the ab initio described solute and the ...
We have carried out self-consistent reaction field (SCRF) calculations on the bacteriochlorophyll (BChl) and bacteriopheophytin (BPh) molecules at the Hartree-Fock level using the ab initio electronic structure code PSGVB together with an accurate numerical Poisson-Boltzmann solver. These are by far the largest ab ...
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...
We applied the locally self-consistent multiple scattering (LSMS) method to the study Fe-based bulk amorphous metals. The LSMS method is an order- N approach to the electronic structure calculation for solid state materials based on density functional the...
Ab initio molecular orbital theory has been used to evaluate several chemical systems. The applicability of the current standard models has been explored. Within the Hartree-Fock self-consistent-field (SCF) and configuration interaction (CI) approaches, t...
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...
as implemented in the Vienna ab initio simulation package (VASP) [6�9]. For the GGA exchange-correlation 0925 All model parameters were evaluated using the Parrot module in Thermo-Calc software [37]. This program
E-print Network
The results of ab-initio molecular self-consistent field calculations with atomic optimized Gaussian bases are reported for the B2O3 molecule. These distinguish between several plausible structures and yield a V-shaped structure as the minimum energy geom...
A recently developed self-consistent ab initio lattice dynamical method has been applied to the high temperature body centered cubic (bcc) phase of La and Th, which are dynamically unstable at low temperatures. The bcc phase of these metals is found to be stabilized by phonon-phonon interactions. The calculated high temperature phonon ...
Formulae are derived for the configuration interaction (CI) energy gradient where the CI is based upon a two-configuration self-consistent-field (TCSCF) reference wave function. A derivation of the analytic CI energy second derivative is presented in Chap...
The coreless Hartree--Fock effective potential (CHFEP) method is used to replace the core orbitals for atoms of the first three rows of the periodic table. Self-consistent field (SCF) calculations indicate that these effective potentials give Hartree--Foc...
We present a generalized definition of subspace occupancy matrices in ab initio methods for strongly correlated materials, such as DFT+U (density functional theory + Hubbard U) and DFT+DMFT (dynamical mean-field theory), which is appropriate to the case of nonorthogonal projector functions. By enforcing the tensorial consistency of all matrix operations, ...
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 ...
Cubic zirconia exhibits a soft phonon mode (X{sup -}{sub 2}), which becomes dynamically unstable at low temperatures. Previous ab initio invest.igations into the temperature-induced stabilization of the soft mode treated it as an independent anharmonic oscillator. Calculations presented here, using the self ...
Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus three-dimensional (3D) structures in Co clusters deposited on Cu(001) finding that the magnetism plays a relevant role. For the magnetic Co25 supported cluster, the influence of such a 2D to 3D structural change on the magnetic properties (magnetic-moment ...
Ab initio calculations for the strongly exoergic Li2+F harpoon reaction are presented using density-functional theory, complete active space self-consistent field, and multireference configuration interaction methods to argue that this reaction would be an ideal candidate for investigation with ultracold molecules. The lowest six ...
... This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and ...
The physical reliability and foundations of the Hund-H�ckel MO-LCAO model, in which a molecular orbital (MO) is represented as a linear combination of atomic orbitals (LCAO), are examined in light of ab initio self-consistent field (SCF) computations with bases of various sizes. It is shown that appropriate linear transformations of ...
A minimum basis set of Slater orbitals has been used for ab initio self-consistent field (SCF) wave functions for B8H12, B9H15, B6H6(2-), B10H10(2-), and B10H14(2-). Bond midpoint densities, overlap populations, atomic charges, molecular dipole moments, d...
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. Formaldehyde was used as a test ...
PubMed
Ab-initio, self-consistent electronic energy bands of zinc blende CdS are reported within the local density functional approximation (LDA). Our first principle, non-relativistic and ground state calculations employed a local density potential and the linear combination of atomic orbitals (LCAO). Within the framework of the Bagayoko, Zhao, and Williams ...
Ab initio self-consistent field results at the UHF/6-31G* and UHF-DZP levels for harmonic vibrational frequencies of symmetric NO{sub 3} with C{sub 2v}, C{sub s}, and D{sub 3h} symmetry; cis and trans forms of OONO are reported. At both levels of calculations (6-31G* and DZP), the theoretical vibrational frequencies for C{sub 2v} ...
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...
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 ...
Ab-initio SCF (self-consistent field) calculations are reported for the optimized geometries of bicyclobutane and the radicals formed by removal of hydrogen from the methylene group and bridgehead C-H bond of bicyclobutane, respectively. The results indicate that the exo, endo, and bridgehead radicals are stable structures on the C/sub 4/H/sub 5/ potential ...
We present a fault tolerant task pool execution environment that is capable of performing fine-grain selective restart using a lightweight, distributed task completion tracking mechanism. Compared with conventional checkpoint/restart techniques, this system offers a recovery penalty that is proportional to the degree of failure rather than the system size. We evaluate this system using the ...
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 ...
The electronic structure of a vacancy in Al was calculated self-consistently using norm-conserving ionic pseudopotentials obtained from ab initio atomic calculations. A 27-atom-site supercell containing 1 vacancy and 26 atoms was used to simulate the environment of the vacancy. A vacancy formation energy of 1.5 eV was also calculated ...
DOE Information Bridge
The extended Lagrangian formulation of time-reversible Born-Oppenheimer molecular dynamics (TR-BOMD) enables the use of geometric integrators in the propagation of both the nuclear and the electronic degrees of freedom on the Born-Oppenheimer potential energy surface. Different symplectic integrators up to the 6th order have been adapted and optimized to TR-BOMD in the framework of ...
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. Effects due to ...
The conductance of a family of ruthenium-octene-ruthenium molecular junctions with different pi conjugation are investigated using a fully self-consistent ab initio approach which combines the nonequilibrium Green's function formalism with density functional theory. Our calculations demonstrate that the continuity of the pi conjugation ...
The conductance of a family of ruthenium-octene-ruthenium molecular junctions with different ? conjugation are investigated using a fully self-consistent ab initio approach which combines the nonequilibrium Green's function formalism with density functional theory. Our calculations demonstrate that the continuity of the ? conjugation ...
Possible high-pressure phases of Al are examined by comparing the total energies for three structures: fcc, bcc, and hcp. The energies are calculated using the density-functional formalism and the ab initio self-consistent pseudopotential approach. At zero pressure, the most stable structure is the fcc structure in agreement with ...
The band structure of tetraza porphin nickel(II) is investigated using semiempirical crystal orbital (CO) calculations for transition metal systems that are based on the INDO approximation. The model Hamiltonian is designed to reproduce the results of ab initio calculations of double-zeta quality at low computational expense. Results show that the various ...
... 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 pseudofunction energy-band method is a full potential, ab initio technique with no adjustable parameters. The basis function is related to the pseudofunction used to create ab initio pseudopotentials. Orthogonalization of the pseudofunction to the core states is accomplished as in the augmented plane-wave ...
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 ...
The results of valence-only self-consistent field calculations on Hgn+ (n = 0, 1, 2) and HgHn+ (n = 0, 1) using nonrelativistic and quasirelativistic energy-adjusted ab initio pseudopotentials for Hg are compared with corresponding all-electron values from nonrelativistic (Hartree-Fock) and relativistic (Dirac-Fock) atomic as well as ...
First-principle studies of magnetic materials at finite temperature are an ultimate step in understanding of mechanisms defining the change of the magnetization and susceptibility with temperature, magnetic phase transition and other magnetic properties and phenomena. We developed an accurate ab-initio method for simulation of magnetic materials at finite temperature. The ...
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 ...
Structures of the ground state pyrrole-(H2O)n clusters are investigated using ab initio calculations. The charge-transfer driven femtosecond scale dynamics are studied with excited state ab initio molecular dynamics simulations employing the complete-active-space self-consistent-field method ...
... 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)
In order to further improve the accuracy and applicability of combined quantum mechanical/molecular mechanical (QM/MM) methods, we have interfaced the ab initio QM method with the classical Drude oscillator polarizable MM force field (ai-QM/MM-Drude). Different coupling approaches have been employed and compared: 1. the conventional dual ...
PubMed Central
We give an account of some recent advances in the development of ab initio methods for the calculation of molecular response properties, involving electric, magnetic, and geometric perturbations. Particular attention is given to properties in which the basis functions depend explicitly both on time and on the applied perturbations such as perturbations ...
We have developed a parameterized semi-empirical Hamiltonian for phosphorous for simulation studies of phosphorous-based nanostructures including phosphorous-doped silicon nanowires.This Hamiltonian models the environment-dependent electron-ion and ion-ion interactions and electron-electron correlations, by capturing the salient features of ab initio ...
Using a diabatic state formalism and pseudospectral numerical methods, we have developed an efficient {ital ab initio} quantum chemical approach to the calculation of electron transfer matrix elements for large molecules. The theory is developed at the Hartree{endash}Fock level and validated by comparison with results in the literature for small systems. ...
The ab initio pseudopotential method is used to study transient-enhanced-diffusion (TED) related processes. The electronic degrees of freedom are included explicitly, together with the fully self-consistent treatment of the electron charge density. A large supercell and a fine k-point mesh are used to ensure numerical convergence. Such ...
An ab initio nonorthogonal valence bond program, called XMVB, is described in this article. The XMVB package uses Heitler-London-Slater-Pauling (HLSP) functions as state functions, and calculations can be performed with either all independent state functions for a molecule or preferably a few selected important state functions. Both our proposed ...
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. ...
Time-reversible ab initio molecular dynamics based on a lossless multichannel decomposition for the integration of the electronic degrees of freedom [Phys. Rev. Lett. 97, 123001 (2006)] is explored. The authors present a lossless time-reversible density matrix molecular dynamics scheme. This approach often allows for stable Hartree-Fock simulations using ...
This article presents an application of the accurate calculation scheme proposed recently for the inner-sphere reorganization energies of molecules of the type AH{sub 2} (A = Al, Si, P, and S). A reasonable extension has been made. The inner-sphere reorganization energies for the title thermal electron self-exchange reactions are calculated in terms of ab ...
Based on {ital ab initio} quantum-chemical methods, accurate calculations on small boron clusters B{sub n} (n=2{endash}14) were carried out to determine their electronic and geometric structures. The geometry optimization with a linear search of local minima on the potential-energy surface was performed using analytical gradients in the framework of the ...
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 of the ...
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 ...
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 ...
A method is presented for expressing the occupied self-consistent-field (SCF) orbitals of a molecule exactly in terms of chemically deformed atomic minimal-basis-set orbitals that deviate as little as possible from free-atom SCF minimal-basis orbitals. The molecular orbitals referred to are the exact SCF orbitals, the free-atom orbitals referred to are the exact atomic SCF ...
We present an implicit solvent model for ab initio electronic-structure calculations which is fully self-consistent and is based on direct solution of the nonhomogeneous Poisson equation. The solute cavity is naturally defined in terms of an isosurface of the electronic density according to the formula of Fattebert and Gygi (J. Comput. ...
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 ...
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 ...
Modern ab initio theories of the magnetic phase transition (Curie Temperature, TC) of Fe and Ni based on the Disordered Local Moment (DLM) type models generally rely on (constrained) density functional theory calculations performed at 0K and assume that the atoms occupy their equilibrium lattice sites. Here we point out that finite temperature lattice ...
We present a new potential energy surface (PES) for the ground state (12A') of the chemical reaction Ne+H2+ from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. The ...
We present a new potential energy surface (PES) for the ground state (1(2)A(')) of the chemical reaction Ne+H(2) (+) from a set of accurate ab initio data, which were computed using highly correlated complete active space self-consistent field and multireference configuration interaction wave functions with a basis set of aug-cc-pV5Z. ...
Intermolecular interaction potentials of the silane dimer in 12 orientations have been calculated by using the Hartree-Fock (HF) self-consistent theory and the second-order M�ller-Plesset (MP2) perturbation theory. We employed basis sets from Pople's medium-size basis sets [up to 6-311++G(3df, 3pd)] and Dunning's correlation consistent basis sets (up to the triply augmented ...
We report a comparison between experimental and theoretical electronic transition dipole moment values for the 7Li2 A 1?u+-X 1?g+ system. The experimental results are based on measuring the absolute magnitude of the transition dipole matrix elements from Autler-Townes splitting of rovibrational transitions for different R-centroid values. The ab initio ...
We report a comparison between experimental and theoretical electronic transition dipole moment values for the (7)Li(2) A (1)Sigma(u) (+)-X (1)Sigma(g) (+) system. The experimental results are based on measuring the absolute magnitude of the transition dipole matrix elements from Autler-Townes splitting of rovibrational transitions for different R-centroid values. The ab ...
The mechanistic photodissociations of several series of aliphatic and aryl halides have been theoretically investigated using multireference ab initio calculations. The photodissociations of halomethanes were also investigated by spin-orbit ab initio calculations. Based on the calculated results of complete active ...
The rhombohedral unit cells of ?-boron crystals and of hypothetical ?-boron quasicrystals were investigated by applying ab initio quantum-chemical methods. The atomic decorations of such unit cells are generally based on a suitable arrangement of eight boron icosahedra, and thus the mechanism of their cohesion was simulated by relaxing a B96 supercluster ...
We report a fragment-based electronic structure method, intended for the study of clusters and molecular liquids, that incorporates electronic polarization (induction) in a self-consistent fashion but treats intermolecular exchange and dispersion interactions perturbatively, as post-self-consistent field corrections, using a form of pairwise symmetry-adapted perturbation theory. The computational ...
We have studied the structural and magnetic properties of the fcc Fe-Co alloy by means of first-principles calculations. For modeling the alloy we have used the ab-initio self-consistent Virtual Crystal Approximation. The ground state properties was calculated with the Fixed Spin Moment methodology and the Full-Potential LAPW method. For the ...
The observations by Farman et al. revealed remarkable depletions in the total atmospheric ozone content in Antarctica. The observed total ozone decreased smoothing during the spring season from about 1975. Satellite observations have proved Antarctic ozone depletions over a very extended region, in general agreement with the local ground-based data of Farman et al. It was suggested that ...
On-the-fly, ab initio classical molecular dynamics are demonstrated with an underlying dual basis set potential energy surface. Dual-basis self-consistent field (Hartree-Fock and density functional theory) and resolution-of-the-identity second-order M�ller-Plesset perturbation theory (RI-MP2) dynamics are tested for small systems, ...
The magnetic properties of transition metal (TM) doped ZnO (TM = Mn2+, Co2+, and Ni2+) were determined by an embedded cluster approach using ab initio methods. We performed CASSCF (complete active space self-consistent field) calculations on clusters with one and two transition metal centers, respectively. In particular, we were ...
Completely self-consistent ab initio calculations of scattering of electrons between the lowest minima of the conduction band by short-wavelength phonons are performed for the first time for a group of А III В V semiconductor crystals. The structure constants, electron and vibrational spectra, and probabilities 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...
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The complete set of 134 isolated-pentagon-rule isomers of C94 has been first investigated by various quantum-chemical approaches. Twenty low-energy cage structures are computed by the ab initio Hartree-Fock self-consistent field method and hybrid density functional theory treatment. All the methods point out a C2 species as the system ...
The crystal structure of the Zr1?xYxNiSn half-Heusler solid solutions is synthesized and their crystal structure is determined. Electrical resistivity and thermoelectric Seebeck coefficient are measured in the 80-380 K temperature range, whereas magnetic susceptibility is measured at 290 K. It is established that substitution of Zr host atoms by Y in the ZrNiSn intermetallic semiconductor is ...
We have generalized the approach for solving the multi-band Gutzwiller variational problem with density-density interaction to an arbitrary local interaction. The main advantage of our formulation is that it allows for a self-consistent numerical implementation which doesn't require any additional computational effort as compared to the simpler case of density-density interaction. Combined with ...
Self-consistent-field calculations have been carried out for the systems AlH and AlH/sup +/ in their ground and excited states. Distances considered range from separated atoms and ions to 0.1 bohr, or ..delta..Eapprox. =2700 eV. Additional calculations were performed to determine the effect of core and valence electrons at small internuclear separations. A comparison was made ...
The relaxation of the prototypical metal oxide surface, rutile TiO{sub 2}(110)1x1, has been elucidated using quantitative low-energy electron diffraction. Successful structure determination entailed the development of adjustable parameter free self-consistent phase shifts, which provide a more reliable description of the electron scattering than traditional approaches. The ...
Superconductivity and magnetism in the new group of rare-earth ternary borides, MRh/sub 4/B/sub 4/, has been reported recently by Matthias et al. Particularly striking has been their observation of reentrant magnetism accompanying the return to a normal state at low temperatures (T = 0.9/sup 0/K) in the superconductor ErRh/sub 4/B/sub 4/ which has a superconducting transition temperature of ...
The structural phase transition at high pressure of heavy rare earth monoantimonides (RESb RE = Ho, Er and Tm) compounds have been studies theoretically using self-consistent tight binding linear muffin tin orbital method. These compound show metallic behavior under ambient condition and undergo a structural phase transition from B1 to B2 phase at high pressure. We predict a ...
With nonequilibrium Green's function approach combined with density functional theory, we perform an ab initio calculation to investigate transport properties of graphene nanoribbon (GNR) junctions self-consistently. Tight-binding approximation is applied to model the zigzag (ZGNR) electrodes, and its validity is confirmed in ...
Ab initio self-consistent field calculations with 4-31G and STO-3G basis sets show that Na+ are able to damage the H bonds in the formamidine\\cdot formamide complex, modeling the adenine-thymine base pair (both H bonds in the complex investigated are the same as in adenine\\cdot thymine). If a water molecule is placed between the ...
We present first-principles calculations for the optical properties of titanium dioxide in the rutile structure. The electronic band structure has been calculated self-consistently within the local-density approximation using {ital ab} {ital initio} pseudopotentials and a plane-wave basis. Optical properties are determined from the ...
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 ...
We applied the locally self-consistent multiple scattering (LSMS) method to the study of Fe-based bulk amorphous metals. The LSMS method is an order-N approach to the electronic structure calculation for solid state materials based on density functional theory and local (spin) density approaximation. Using LSMS method, we performed electronic structure calculations for the ...
The addition and abstraction reaction pathways on the potential energy surface for H + HCO have been characterized by an ab initio four electron, complete active space, self-consistent field electronic structure calculation. The elimination pathway to go from the excited adduct H/sub 2/CO to products H/sub 2/ + CO has already been ...
The addition and abstraction reaction pathways on the potential energy surface for H+HCO have been characterized by an ab initio four electron, complete active space, self-consistent field electronic structure calculation. The elimination pathway to go from the excited adduct H/sub 2/CO to products H/sub 2/+CO has already been ...
Detailed results are reported of ab-initio self-consistent LMTO energy band studies of several Chevrel phase ternaries, EuMo/sub 6/S/sub 8/ and SnMo/sub 6/S/sub 8/. In these unique calculations, all electrons of the full 15 atoms/unit cell are treated explicitly with a self-consistent Hedin-Lundqvist exchange and correlation potential in the relativistic ...
We present calculated, electronic and related properties of wurtzite cadmium sulfide (w-CdS). Our ab-initio, non-relativistic calculations employed a local density functional approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). Following the Bagayoko, Zhao, and Williams (BZW) method, we solved self-consistently both the ...
Ab initio DFT electronic structure calculations involve an iterative process to solve the Kohn-Sham equations for an Hamiltonian depending on the electronic density. We discretize these equations on a grid by finite differences. Trial eigenfunctions are improved at each step of the algorithm using multigrid techniques to efficiently reduce the error at all ...
We have performed ab initio self-consistent calculations based on full potential linear augmented plane-wave method (FP-LAPW) with the local density approximation (LDA) and generalised gradient approximation (GGA) to investigate the relativistic effects on the structural, electronic, transport and optical properties of II-VI compounds. ...
Water at elevated temperatures and pressures in attracting interest as a reaction medium and an environmentally benign alternative to organic solvents. The fugacity coefficients of the hydroperoxyl radical in supercritical water are estimated through molecular simulations. A potential function for the radical is first derived from ab initio ...
We describe ab initio, self-consistent, 3D, fully electromagnetic numerical simulations of current drive and field-reversed-configuration plasma formation by odd-parity rotating magnetic fields (RMF{o}). Magnetic-separatrix formation and field reversal are attained from an initial mirror configuration. A population of ...
We describe ab initio, self-consistent, 3D, fully electromagnetic numerical simulations of current drive and field-reversed-configuration plasma formation by odd-parity rotating magnetic fields (RMFo). Magnetic-separatrix formation and field reversal are attained from an initial mirror configuration. A population of ...
We use a combination of molecular dynamics (MD) and first-principles techniques to study the structure and energies of twin boundaries in hcp zirconium. The empirical many-body potential of Zr is used to test the stability of various possible twin structures, but the final relaxed positions are accurately determined using fully self-consistent ab ...
Decomposition of energetic molecules such as pentaerythritol tetranitrate is accompanied by extensive changes in their electronic configuration and thus is challenging for ab initio Born-Oppenheimer molecular dynamics simulations. The performance of single-determinant methods (in particular, density-functional theory) is validated on electronic structure ...
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 ...
In support of tokamak edge plasma studies, we calculate the electron-impact ionization cross section for the ground state of the diatomic carbon molecule. Bound orbitals for C2 and C+2 are calculated using a single-configuration self-consistent-field method based on a linear combination of Slater-type orbitals. Continuum distorted-wave orbitals are calculated using a ...
This report describes an alternative to MD (molecular dynamics) and the empirical methods based on treating the solvent as a polarizable, continuous medium (PCM). This model excludes many important properties of water such as explicit hydrogen bonding and size effects, but includes other properties of water that would otherwise only be accessible from computationally intensive MD. This report ...
Conventional first principle methods for calculating lattice dynamics are unable to calculate high temperature thermophysical properties of materials containing modes that are entropically stabilized. In this presentation we use a relatively new approach called self-consistent ab initio lattice dynamics (SCAILD) to study the hcp to bcc ...
A new two-configuration self-consistent field (SCF) plus dispersion potential for the interaction of OH with H[sub 2] is presented. The ground state of OH is a [sup 2][Pi] state leading to a two component potential which is diagonal in the adiabatic electronic basis in which the quantum chemical calculations are done. The transformation between the adiabatic basis and the ...
Analytical potential energy derivatives, based on the Hellmann-Feynman theorem, are presented for any pair of isoelectronic compounds. Since energies are not necessarily monotonic functions between compounds, these derivatives can fail to predict the right trends of the effect of alchemical mutation. However, quantitative estimates without additional self-consistency ...
We compute the linear optical properties of different reconstructions of the clean and hydrogenated Si(100) surface within DFT-LDA, using norm conserving pseudopotentials. The equilibrium atomic geometries of the surfaces, determined from self-consistent total energy calculations within the Car-Parrinello scheme, influence strongly the Reflectance Anisotropy Spectra, showing ...
The coreless Hartree--Fock effective potential (CHFEP) method is used to replace the core orbitals for atoms of the first three rows of the periodic table. Self-consistent field (SCF) calculations indicate that these effective potentials give Hartree--Fock quality orbitals and orbital energies. Optimized small basis sets for use with these effective potentials are presented ...
Self-consistent field calculations have been performed on the compounds FNO{sub x} (x = 1, 2, 3) using 4-31G, 6-31G*/MP2, and PDZ/MP2 basis sets. Dipole moments, Koopman's ionization potentials, and predicted geometries are reported. The predicted relative stability for FNO{sub 2} isomers is FNO{sub 2} > c-FONO > t-FONO. FONO{sub 2} is predicted to only slightly ...
Catalytic, chemical, optical and electronic properties of nanocrystals are strongly influenced by their faceting. A variational approach based on quantum mechanical energies is introduced to evaluate stable and metastable shapes of nanocrystals. The method leads to a nanoscale equation of state, which is solved self-consistently. Using platinum as example, it is found that the ...
Two kinds of junctions based on doped graphene nanoribbons (GNRs) are designed and studied in this article. One is the N-doped armchair GNR (AGNR) joined directly by B-doped AGNRs, and another is similar, but there is an undoped AGNR between them. The transport properties are calculated using the full self-consistent ab initio ...
We present a theoretical method for locating the lowest free-energy points on conical intersections (CIs) in solution using the reference interaction site model self-consistent field (RISM-SCF) theory. Based on the linear-response theory, the nonequilibrium free energy is defined as a quadratic function of solvation coordinates, the parameters in which are directly obtained by ...
Ab initio Hartree-Fock (HF), density functional theory (DFT) and second-order M�ller-Plesset (MP2) methods were used to perform harmonic and anharmonic calculations for the biomolecule cytosine and its deuterated derivative. The anharmonic vibrational spectra were computed using the vibrational self-consistent field (VSCF) and ...
The sensitivity of Pt L-edge XANES to local geometric and electronic structure in various Pt(n) clusters is investigated using the ab initio self-consistent FEFF8 code. Calculations based on FEFF8 are found to be in good agreement with experiment. For pure Pt clusters the XANES can distinguish between 2- and 3-dimensional clusters. ...
We present a new ab initio method for electronic structure calculations of materials at finite temperature (FT) based on the all-electron quasiparticle self-consistent GW (QPscGW) approximation and Keldysh time-loop Green's function approach. We apply the method to Si, Ge, GaAs, InSb, and diamond and show that the band gaps of ...
Analytical energy gradient formula was derived for reference interaction site model self-consistent field explicitly including spatial electron density distribution (RISM-SCF-SEDD). RISM-SCF-SEDD is a combination method of ab initio electronic structure theory and statistical mechanics for molecular liquids [D. Yokogawa et al., J. ...
... 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 ...
... Abstract : Results are presented from ab initio quantum chemical calculations on the ground state potential energy surface for the open shell ...
... 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). ...
... We carried out ab-initio quantum chemical calculations on these energetic cyclic ethers and generated the electrostatic molecular potential contour ...
Ab initio quantum chemical techniques have been used to investigate weakly bund complexes of H20 and SO2. An energy gradient program was used to ...
... Accession Number : ADA351780. Title : Ab Initio and DFT Potential Energy Surfaces for Cyanuric Chloride Reactions. Descriptive Note : Final rept. ...
... Ab initio study on atomic structures and physical properties of CdSe quantum nanodots ... Figure 2. Diagram of covered nanodots. ...
... Title : Ab Initio Study on Atomic Structures and Physical Properties of CdSe Quantum Nanodots. Descriptive Note : Final rept. ...
... 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 ...
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. ...
... 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 ...
