Relativistic configuration-interaction calculation of Kα transition energies in beryllium-like argon

Relativistic configuration-interaction calculations have been performed for energy levels of the low-lying and core-excited states of beryllium-like argon, Ar¹⁴⁺. These calculations include the one-loop quantum electrodynamics (QED) effects as obtained by two different methods: the screening-potential approach and the model QED operator approach. The calculations are supplemented by a systematic estimation of the uncertainties of the theoretical predictions. (paper)