Excitation energies and transition rates in the3d2states of Ca-like ions

Abstract

Energies, transition probabilities, and lifetimes are calculated for ${3d}^{2}$ states in Ca-like ions with nuclear charges Z ranging from 22 to 100. Relativistic many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded $M1$ and $E2$ matrix elements. The calculations start from a ${1s}^{2}{2s}^{2}{2p}^{6}{3s}^{2}{3p}^{6}$ Dirac-Fock potential. First-order perturbation theory is used to obtain intermediate coupling coefficients and second-order MBPT is used to determine matrix elements. Contributions from negative-energy states are included in the second-order $M1$ and $E2$ matrix elements. The resulting transition energies and lifetimes are compared with experimental values and with results from other recent calculations.