2008/12/03 by Paola Gori-Giorgi, Giovanni Vignale, Michael Seidl · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.other
published as J. Chem. Theory Comput. 5, 743 (2009) · 11 pages, submitted to J. Chem. Theory Comput
arxiv created 2008/12/03 · arxiv updated 2009/12/01
The exchange-correlation energy in Kohn-Sham density functional theory can be expressed exactly in terms of the change in the expectation of the electron-electron repulsion operator when, in the many-electron hamiltonian, this same operator is multiplied by a real parameter λ varying between 0 (Kohn-Sham system) and 1 (physical system). In this process, usually called adiabatic connection, the one-electron density is kept fixed by a suitable local one-body potential. The strong-interaction limit of density functional theory, defined as the limit λ→∞, turns out to be, like the opposite non-interacting Kohn-Sham limit (λ→ 0) mathematically simpler than the physical (λ=1) case, and can be used to build an approximate interpolation formula between λ→ 0 and λ→∞ for the exchange-correlation energy. Here we extend the exact treatment of the λ→∞ limit [Phys. Rev. A \bf 75, 042511 (2007)] to the next leading term, describing zero-point oscillations of strictly correlated electrons, with numerical examples for small spherical atoms. We also propose an improved approximate functional for the zero-point term and a revised interpolation formula for the exchange-correlation energy satisfying more exact constraints.