Uniform electron gas from the Colle-Salvetti functional: Missing long-range correlations - art. no. 032513

Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)] approximated the corr elation energy of a many- electron system as a functional of the Hartree-Fo ck one-particle density matrix. The most fundamental and least approximate version of this functional [their Eq. (9)] is found to yield only 25% of th e true correlation energy of a uniform electron gas, and not 100% as previo usly believed. While short-range correlations are described surprisingly we ll by this approach, important long-range correlations are missing. Such co rrelations are energetically negligible in atoms, but cannot be ignored in more extended systems, including solids as well as molecules.