نتایج جستجو برای: ab initio calculation
تعداد نتایج: 143349 فیلتر نتایج به سال:
We have performed quantum-chemical ab initio in various basis sets at the Hartree-Fock andB3LYP levels for Adenine and Thymine with the program GAUSSIAN98. The Dipole,Quadrupole, Octapole and Hexadecapole moments and primitive in nine basis sets for thesemolecules are presented. The most stabilized forms of these molecules are observed in 6-311++G** basis set. We have evaluated coefficient hybr...
An ab initio Wannier-function-based approach to electronic groundstate calculations for crystalline solids is outlined. In the framework of the linear combination of atomic orbitals method the infinite character of the solid is rigorously taken into account. The Hartree-Fock groundstate energy, cohesive energy, lattice constant and bulk modulus are calculated in a fully ab initio manner as it i...
From ultracold atoms to quantum chromodynamics, reliable ab initio studies of strongly interacting fermions require numerical methods, typically in some form of quantum Monte Carlo calculation. Unfortunately, (non)relativistic systems at finite density (spin polarization) generally have a sign problem, such that those ab initio calculations are impractical. It is well-known, however, that in th...
We have performed an ab initio study of BaF2 by employing different program packages. Ground-state and lattice-dynamical properties are obtained from ab initio density-functional theory within local-density approximation LDA and generalized-gradient approximation GGA employing pseudopotentials and plane-wave basis sets, the electronic properties also from full-potential LAPW+LMTO methods. The r...
We present an ab initio pseudopotential local density functional calculation for stoichiometric high-Tc cuprate YBa2Cu3O7 using the plane-wave basis set. We have overcome well-known difficulties in applying pseudopotential methods to first-row elements, transition metals, and rare-earth materials by carefully generating norm-conserving pseudopotentials with excellent transferability and employi...
We establish a method for exploring the dynamics of molecular quantum-dot cellular automata QCA devices by hierarchically combining the techniques of quantum chemistry with the nonequilibrium time-dependent coherence vector formalism. Single QCA molecules are characterized using ab initio quantum chemistry methods. We show how to construct a simple model Hamiltonian for each QCA cell based on p...
The crystal structures and hydraulic activities of β and γform dicalcium silicates (β-C2S, γ-C2S) were analyzed by ab-initio calculation based on quantum mechanics. The mean distances less than 4 Å to the neighboring Ca atoms for all of independent Ca atoms were calculated within unit cell. Ca-Ca mean distances are 3.56 Å in β-C2S and 3.75 Å in γ-C2S. The shortening of Ca-Ca distance causes ins...
Citation Ceresoli, D. et al. " Ab initio converse NMR approach for pseudopotentials. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We extend the recently develop...
Classical simulations of the reactions between HCO+/COH+ and hydrogen atoms, as well as their deuterated variants, have been carried out on an ab initio interpolated potential energy surface. The surface is constructed at the quadratic configuration interaction with single and double excitation level of ab initio calculation. At low energies we observe reaction channels associated with the isom...
We review the young field of ab initio molecular dynamics applied to molecule-surface reactions. The techniques of ab initio molecular dynamics include methods that use an analytic potential energy function fit to ab initio data and those that are fully ab initio. In this review, we focus on the insights provided by ab initio-based molecular dynamics that are currently unavailable from experime...
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