Relativistic multireference Moller-Plesset perturbation theory based on multiconfigurational Dirac-Fock reference functions

Relativistic multireferencee Moller-Plesset perturbation theory is developed and implemented with analytic basis sets of Gaussian spinors. The theory takes multiconfigurational Dirac-Fock self-consistent field wavefunctions as reference functions. A procedure is described by which to perform multireference second-order Moller-Plesset perturbation theory calculations for a general class of reference functions constructed from one-particle Dirac spinors. Multireference perturbation calculations are reported for the ground and low-lying excited states of oxygen-like iron, Fe18+ (Z = 26), and ground-state Zn-0, in which the near degeneracy of a manifold of strongly interacting configurations mandates a multireference treatment. (C) 1998 Elsevier Science B.V. All rights reserved.