An investigation of the annihilated unrestricted Hartree–Fock wave function and its use in second-order Mo/ller–Plesset perturbation theory

Abstract

The recently introduced annihilated unrestricted Hartree–Fock (AUHF) wave function—in which the first spin contaminant in an unrestricted Hartree–Fock (UHF) wave function has been annihilated self-consistently—is discussed in some detail with particular attention to its use as a basis for a perturbation expansion. A series of calculations are presented highlighting the advantages and disadvantages of a second-order Mo/ller–Plesset (AUMP2) perturbation treatment.