Accurate adapted Gaussian basis sets for helium- and beryllium-like atomic species to be used in Dirac–Fock calculations

Abstract

The closed-shell Generator Coordinate Dirac–Fock method is applied to perform Dirac–Fock–Coulomb and Dirac–Fock–Breit calculations for He- and Be-like atomic species. With the Generator Coordinate Dirac–Fock method, the integral Dirac–Fock equations are integrated numerically in order to generate accurate adapted Gaussian basis sets for the atomic species under study. The Dirac–Fock–Coulomb and Dirac–Fock–Breit energies obtained here for He- and Be-like atomic species with the Generator Coordinate Dirac–Fock formalism are in general better than the corresponding energies obtained with previous Gaussian-type functions. The Dirac–Fock–Coulomb energies obtained for the atomic species here studied are in excellent agreement with numerical-finite-difference calculations, and for several atomic species the Dirac–Fock–Coulomb energy results obtained with our adapted Gaussian basis sets are lower than the corresponding energies obtained from numerical-finite-difference calculations.