Relativistic many-body calculations of energies of n = 3 states for boron-like sodium

Energies of 2s23l, 2s2p(1P)3l, 2s2p(3P)3l and 2p23l states (with l = s, p, d) for B-like Na are calculated. These perturbation-theory calculations make use of a frozen-core relativistic Hartree-Fock basis sets. The calculations include Coulomb and Breit contributions from first- and second-order diagrams for both diagonal and non-diagonal matrix elements. Corrections for the frequency-dependent Breit interaction are taken into account in lowest order and corrections for the Lamb shift are also included. Contributions from three-electron diagrams are compared with those from one- and two-electron diagrams. Comparisons are made with available experimental data; we find good agreement in most cases with experimental term-splitting values in ions with small nuclear charge.