Atomic Dirac-Fock-Breit self-consistent field calculations

The frequency-independent Breit interaction, which gives the leading correction to the instantaneous Coulomb interaction, is treated self-consistently in matrix Dirac–Fock–Breit self-consistent field (SCF) calculations. Calculations were done on He, He-like ions, Be, Be-like ions, Ne, and Ar. Basis sets of even- and well-tempered Gaussian functions were used to expand the large and small components of Dirac 4-spinors. The results of the variational calculations are compared with Desclaux's benchmark numerical perturbative calculations.