Accurate exchange-correlation potentials and total-energy components for the helium isoelectronic series
- Cornell Theory Center and Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853 (United States)
- Unite de Physico-Chemie et de Physique des Materiaux, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium)
Starting from very accurate many-body wave functions, we have constructed essentially exact densities, exchange-correlation potentials, and components of the total energy for helium and two-electron ions. These density-functional results are compared to the corresponding quantities obtained from a variety of commonly used approximate density functionals, namely, the local-density approximation and various generalized gradient approximations, in order to test the accuracy of the approximate functionals. Although the generalized gradient approximations yield improved energies compared to the local-density approximation, the exchange and correlation potentials (especially the latter) obtained from the generalized gradient approximations are in poor agreement with the corresponding exact potentials. The large-distance asymptotic behavior of the exact exchange-correlation potential to [ital O](1/[ital r][sup 4]) is found to agree with theoretical predictions. The short-range behavior of the exchange-correlation potential is very close to quadratic. The prospects for improved generalized gradient approximations are discussed.
- OSTI ID:
- 6836867
- Journal Information:
- Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 50:5; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
ASYMPTOTIC SOLUTIONS
ATOMS
CALCULATION METHODS
CHARGED PARTICLES
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY
FLUIDS
FUNCTIONS
GASES
HARTREE-FOCK METHOD
HELIUM
IONS
ISOELECTRONIC ATOMS
MULTICHARGED IONS
NONMETALS
RARE GASES
WAVE FUNCTIONS