GENERALIZED GRADIENT APPROXIMATION TO THE ANGLE-AVERAGED AND SYSTEM-AVERAGED EXCHANGE HOLE

Citation
M. Ernzerhof et Jp. Perdew, GENERALIZED GRADIENT APPROXIMATION TO THE ANGLE-AVERAGED AND SYSTEM-AVERAGED EXCHANGE HOLE, The Journal of chemical physics, 109(9), 1998, pp. 3313-3320
Citations number
48
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
ISSN journal
0021-9606
Volume
109
Issue
9
Year of publication
1998
Pages
3313 - 3320
Database
ISI
SICI code
0021-9606(1998)109:9<3313:GGATTA>2.0.ZU;2-V
Abstract
A simple analytic model is proposed for the angle- and system-averaged exchange hole of a many-electron system. The model hole depends on th e local density and density gradient. It recovers a nonoscillatory loc al-spin density (LSD) approximation to the exchange hole for a vanishi ng density gradient. The model hole reproduces the exchange energy den sity of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approxim ation (GGA) for;exchange, and facilitates a detailed understanding of the PBE GGA. The hole model is applied to atoms and molecules, and a c omparison is made to exact and LSD angle- and system-averaged exchange holes. We fmd that the GGA hole model significantly improves upon the LSD model. Furthermore, the GGA hole model accurately describes the c hange in the exchange hole upon the formation of single bonds, but is less accurate for the formation of multiple bonds, where it misses the appearance pf a long-range tail. (C) 1998 American Institute of Physi cs.