L. NEDINt and B. I. LUNDQVIST fS t
Department of theoretical physics, University of Lund. Lund, Sweden f Laboratory of Solid State and Atomic Physics. Cornell University, Ithaca, NY 14850, MS.
received 29th March 1971
Abstract:
The possibilities of the Hohenberg-Kohn-Sham local density theory are explored in view of recent advances in the theory of the interacting electron gas. We discuss and provide numerical data for the effective exchange-correlation potentials pxc for ground state problems and V,, for excitation spectra. The potential pxc(v) is written as a factor p(p(v)), which depends on the local density p(v), times the Kohn-Sham-Gaspar potential px = - e2k,/7r. The factor p, which is represented by a simple analytical formula, varies between 1 for very high densities and about 1.5 for very low densities, where pxc thus approaches the Slater approximation. The potential V,, is given in the form of a table. The explicit predictions of the approximate theories are mapped in their linearized versions, and found to compare favourably with recent work by Geldart and Taylor, Singwi et al. and others. The theory is also developed for the case when the ion cores are treated separately, and the local density approximation is applied only to the valence electrons.
The schemes proposed here are no more difficult to apply than presently used local approximations for exchange, but they should be much more accurate.
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