Relativistic many-body perturbation calculations for open-shell systems

Relativistic correlation energies have been computed for the open-shell ground states of group I B and III A elements up to Z = 79 (B, Al, Ga, In, Cu, Ag, Au), as well as their singly ionized closed-shell ions, by means of a recently developed relativistic many-body perturbation theory for open-shell multiplet states. All electrons are included in the correlation calculations. Analytic basis sets of Gaussian spinors are employed to expand the upper and lower components of the Dirac four-spinors in open-shell matrix Dirac-Fock and relativistic many-body perturbation procedures. The state-specific relativistic many-body perturbation theory for open-shell multiplet states involves a full implementation of generalized Moller-Plesset perturbation theory and accounts for both relativistic and electron correlation effects. The ionization energies have been calculated for the atoms, and the effects of relativity, electron correlation, and the nonadditive interplay of these effects on the ionization energies are analyzed.