Results 271 to 280 of about 6,241,670 (306)

Density Functional Calculations

2010
Density functional theory is based on the two Hohenberg-Kohn theorems, which state that the ground-state properties of an atom or molecule are determined by its electron density function, and that a trial electron density must give an energy greater than or equal to the true energy (the latter theorem is true only if the exact functional could be used).
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Density functional calculations of surface free energies

The Journal of Chemical Physics, 2006
We propose a general method of thermodynamic integration to find the free energy of a surface, where our integration parameter is taken to be the strain on the unit cell of the system (which in the example presented in this paper is simply the extension of the unit cell along the normal to the surface), and the integration is performed over the thermal
H, Fox, A P, Horsfield, M J, Gillan
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Density-functional calculations for grain boundaries in aluminum

Physical Review B, 1994
The plane-wave pseudopotential (PWPP) method is used to perform density-functional-theory (DFT) calculations for two grain boundaries in aluminum studied previously using the embedded-atom method (EAM) and high-resolution transmission electron microscopy: (1) a \ensuremath{\Sigma}=11 (11\ifmmode\bar\else\textasciimacron\fi{}3)129\ifmmode^\circ\else ...
, Wright, , Atlas
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Performance of parallel TURBOMOLE for density functional calculations

Journal of Computational Chemistry, 1998
The parallelization of density functional treatments of molecular electronic energy and first-order gradients is described, and the performance is documented. The quadrature required for exchange correlation terms and the treatment of exact Coulomb interaction scales virtually linearly up to 100 nodes.
Arnim, Malte von, Ahlrichs, Reinhart
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Relativistic all-electron density functional calculations

Journal of Computational Chemistry, 1999
The current status of relativistic density functional theory is reviewed. For most applications relevant to chemistry, relativistic corrections to the electron interaction and radiative corrections are not important, and the (four-component) Dirac–Kohn–Sham model can be viewed as a reference.
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Calculation of nonadiabatic couplings in density-functional theory

The Journal of Chemical Physics, 2004
This paper proposes methods for calculating the derivative couplings between adiabatic states in density-functional theory (DFT) and compares them with each other and with multiconfigurational self-consistent field calculations. They are shown to be accurate and, as expected, the costs of their calculation scale more favorably with system size than ...
Salomon R, Billeter, Alessandro, Curioni
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Approximate occupation functions for density-functional calculations

Physical Review B, 1997
The density-functional free energy can be written in a form that is stationary with respect to variations in the occupation function. For this reason it is useful to look for approximate occupation functions that are sufficiently close to the Fermi function that accuracy is not compromised and yet have advantages for computation.
D. M. C. Nicholson, X.-G. Zhang
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Density Functional Calculations of Thermochemical Equilibria

The Journal of Physical Chemistry A, 1998
Computationally practical quantum-mechanical methods are needed in order to determine the ideal-gas thermodynamic properties of moderate-size molecules. In this work, we attempt to utilize density functional theory with B3LYP functional to calculate thermodynamic quantities of organic molecules of moderate sizes and to apply the results to characterize
Hansong Cheng, Vipul S. Parekh, John W. Mitchell, Kathryn S. Hayes   +3 more
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Accurate density functional calculations on large systems

International Journal of Quantum Chemistry, 1996
Efforts to compute accurate all-electron density-functional energies for large molecules and clusters using Gaussian basis sets are reviewed and their use in fullerene science described. The foundation of this effort, variational fitting, is described first.
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Density Functional Calculations of Molecular Bond Energies

The Journal of Chemical Physics, 1986
The calculation of molecular bond energies is a sensitive test of exchange-correlation approximations in density functional theory. The well known local density approximation (LDA) gives excellent bond lengths and vibrational frequencies, but seriously overestimates dissociation energies.
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