Energy levels of the ground state and the 2s2pn(J=1) excited states of berylliumlike ions: A large-scale, relativistic configuration-interaction calculation

We have calculated energy levels of the ${2\mathrm{s}}^2$ ${\mathrm{}}^1$ ${\mathrm{S}}_0$ ground state and the 2s2p${\mathrm{}}^{1,3}$ ${\mathrm{P}}_1$ excited states of berylliumlike ions with Z=10–92 using the relativistic configuration-interaction method. These calculations are based on the relativistic no-pair Hamiltonian which includes Coulomb and retarded Breit interactions and employ finite B-spline basis functions. Quantum electrodynamic and mass polarization corrections are also calculated. Good agreement between theory and experiment for the ${2\mathrm{s}}^2$ ${\mathrm{}}^1$ ${\mathrm{S}}_0$-2s2p${\mathrm{}}^{1,3}$ ${\mathrm{P}}_1$ transition energies is found throughout the isoelectronic sequence.