Calculation of quasi-degenerate energy levels of two-electron ions

Abstract: Accurate QED calculations of the interelectron interaction corrections for the $(1s2p)2 {}¹ P_1$, $(1s2p)2 {}³ P_1$ two-electron configurations for ions with nuclear charge numbers $10\le Z \le 92$ are performed within the line profile approach. Total energies of these configurations are evaluated. Employing the fully relativistic treatment based on the {$j$--$j$} coupling scheme these energy levels become quasi-degenerate in the region $Z\le 40$. To treat such states within the framework of QED we utilize the line profile approach. The calculations are performed within the Coulomb gauge.