RELATIVISTIC MANY-BODY PERTURBATION-THEORY FOR GENERAL OPEN-SHELL MULTIPLET STATES OF ATOMS

A relativistic many-body perturbation theory, which accounts for relat ivistic and electron-correlation effects for general open-shell multip let states of atoms and molecules, is developed and implemented with a nalytic basis sets of Gaussian spinors. The theory retains the essenti al aspects of Moller-Plesset perturbation theory by employing the rela tivistic single-Fock-operator method of Koc and Ishikawa [Phys. Rev. A 49, 794 (1994)] for general open-shell systems. Open-shell Dirac-Fock and relativistic many-body perturbation calculations are reported for the ground and low-lying excited states of Li, B2+, Ne7+, and Ca11+.