Exchange and correlation in open systems of fluctuating electron number

John P. Perdew, Adrienn Ruzsinszky, Gábor I. Csonka, Oleg A. Vydrov, Gustavo E. Scuseria, Viktor N. Staroverov, Jianmin Tao

Research output: Contribution to journalArticle

124 Citations (Scopus)


While the exact total energy of a separated open system varies linearly as a function of average electron number between adjacent integers, the energy predicted by semilocal density-functional approximations is concave up and the exact-exchange-only or Hartree-Fock energy is concave down. As a result, semilocal density functionals fail for separated open systems of fluctuating electron number, as in stretched molecular ions A2+ and in solid transition-metal oxides. We develop an exact-exchange theory and an exchange-hole sum rule that explain these failures and we propose a way to correct them via a local hybrid functional.

Original languageEnglish
Article number040501
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number4
Publication statusPublished - Oct 10 2007

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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