Applications of the relativistic equation of motion to photoionization of Mg-like ions

Abstract As an approximation to the relativistic equation of motion, the multiconfiguration relativistic random-phase approximation theory is applied to the valence-shell photoionization of the Mg-like ions. Photoionization cross sections between ( 2 p 6 3 s ) 2 S 1 / 2 and ( 2 p 6 3 p ) 2 P 1 / 2 0 ionization thresholds are calculated. The main feature of our results is exhibited by five Rydberg series of doubly excited states arising from fine-structure splittings. A comparative study of Al + , Si 2+ , P 3+ , S 4+ , Cl 5+ , and Ar 6+ is presented.