Relativistic many-body calculations of energies of n=3 states in aluminumlike ions

Energies of 3l3l^′3l^″ states of aluminumlike ions with Z=14–100 are evaluated to second order in relativistic many-body perturbation theory starting from a 1s²2s²2p⁶ Dirac-Fock potential. Intrinsic three-particle contributions to the energy are included in the present calculation and found to contribute about 10–20 % of the total second-order energy. Corrections for the frequency-dependent Breit interaction and the Lamb shift are included in lowest order. A detailed discussion of contributions to the energy levels is given for aluminumlike germanium (Z=32). Comparisons are made with available experimental data. We obtain excellent agreement for term splitting, even for low-Z ions. These calculations are presented as a theoretical benchmark for comparison with experiment and theory.