Correlation Energy Functionals of One-Matrices and Hartree-Fock Densities

Abstract

Only a small piece of the exact universal variational functional of the 1-matrix is actually unknown. The unknown piece, Ec[.gamma.], is identified and several rigorous properties of it are derived. Based upon these derived properties, approx. forms of Ec[.gamma.] are displayed for the purpose of actual calcns. Existence theorems are then proved which allow the single-shot detn. of exact correlation energies directly from Hartree-Fock and exchange-only densities. All ground-state and excited-state properties of the system are detd. by these densities. The existence theorems do not generally apply to finite basis sets. Ec[.gamma.] Is compared with ~Ec[.rho.], which is the single-shot universal correlation energy functional of the Hartree-Fock d. which is put forth as the correction to the Hartree-Fock energy.