نتایج جستجو برای: functional theories
تعداد نتایج: 689388 فیلتر نتایج به سال:
We introduce a short-range correlation density functional defined with respect to a multi-determinantal reference which is meant to be used in a multi-determinantal extension of the Kohn–Sham scheme of density functional theory based on a long-range/short-range decomposition of the Coulomb electron–electron interaction. We construct the local density approximation for this functional and discus...
The importance of including spin-orbit interactions for the correct description of structures and vibrational frequencies of haloiodomethanes is demonstrated by density functional theory calculations with spin-orbit relativistic effective core potentials (SO-DFT). The vibrational frequencies and the molecular geometries obtained by SO-DFT calculations do not match with the experimental results ...
A screening study of the steam reforming reaction on clean and oxygen covered early transitionmetal carbides surfaces is performed by means of density-functional theory calculations. It is found that carbides provide a wide spectrum of reactivities, from too reactive via suitable to too inert. Several molybdenum-based systems are identified as possible steam reforming catalysts. The findings su...
The self-assembly of sphere-forming triblock copolymers confined between two thin homogeneous surfaces is investigated based on mean-field dynamic density functional theory. The morphologies deviating from the bulk sphere-forming phase are revealed, including cylinders oriented perpendicular to the surface, cylinders oriented parallel to the surface, perforated lamellae and lamellae by varying ...
The reliability of density functional theory ~DFT! for the prediction of equilibrium molecular properties is assessed for several challenging molecules (F2 , O2 , O2, O4 , F4 , and NO3) which tend to artifactually break spatial symmetry in the Hartree–Fock approximation. DFT appears to be among the more robust methods for such cases, but it is not immune to anomalous property predictions. The B...
We consider the pairing Hamiltonian and systematically construct its density functional in the strong-coupling limit and in the limit of large particle number. In the former limit, the functional is an expansion into central moments of occupation numbers. In the latter limit, the functional is known from BCS theory. Both functionals are nonlocal in structure, and the nonlocalities are in the fo...
First-principles calculations of substitutional defects and vacancies are performed for zigzag-edged hybrid C/BN nanosheets and nanotubes which recently have been proposed to exhibit half-metallic properties. The formation energies show that defects form preferentially at the interfaces between graphene and BN domains rather than in the middle of these domains, and that substitutional defects d...
Approximate solution of the ensemble representability problem for density operators of arbitrary order is obtained. This solution is closely related to the " Q condition " of A. J. Coleman. The representability conditions are formulated in orbital representation and are easy to use. They are tested numerically on the base of CI calculation of simple atomic and molecular systems. General scheme ...
In this article, we describe a C/C++ program called SurfKin (Surface Kinetics) to construct microkinetic mechanisms for modeling gas-surface reactions. Thermodynamic properties of reaction species are estimated based on density functional theory calculations and statistical mechanics. Rate constants for elementary steps (including adsorption, desorption, and chemical reactions on surfaces) are ...
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