Random-phase approximation with exchange for the photoionization of an atom with an inner open shell

Abstract

A random-phase approximation with exchange method has been developed for the photoionization of atoms (ions) with an inner open shell. The method allows for the inclusion of both intrashell and intershell correlations in the calculation and has been used to study the photoelectron asymmetry parameter and the cross sections of the Sc $4s$ photoionization in which the Sc $3p\text{\ensuremath{-}}3d$ transitions have been successfully included. The results demonstrate that the inclusion of the $3p\text{\ensuremath{-}}3d$ transitions is extremely important in the intershell coupling, which significantly influences the calculated asymmetry parameter and the cross sections of the Sc $4s$ photoionization. Comparison of our calculated asymmetry parameter and the cross sections with the measured data and available calculation is made and discussed. Possible improvements to the present calculated data are offered as well.