HYLLERAAS-TYPE CALCULATIONS OF THE RELATIVISTIC CORRECTIONS FOR THE GROUND-STATE OF THE LITHIUM ATOM

Calculations of the principal Breit-Pauli relativistic corrections for the ground-state energy of the lithium atom have been carried out. Th e corrections have been determined using first-order perturbation theo ry. Only the non-fine-structure components of the Breit-Pauli Hamilton ian in the infinite nuclear mass approximation are considered. The wav e function employed is an extensively optimized large-scale Hylleraas- type expansion. Comparisons are made with the few available relativist ic corrections for the lithium atom that are available in the literatu re. A reevaluation of the first ionization potential for the ground st ate of Li is presented. [S1050-2947(98)05911-3].