Initial-state correlation in the electron-impact ionization of argon

Ionization of the 3p orbital of argon by 113.5 and 200 eV incident electrons is studied by means of the post version of the CDW-EIS model. Results are presented for 2, 5, and 10 eV ejected electrons and compared to recent experimental data from Lohmann and collaborators. The present results are also compared to those obtained by other state-of-the-art theoretical methods. The present system is extremely sensitive to the way in which the post-collision interaction, the electronic exchange and the initial state correlation are considered. We conclude that none of the here discussed methods provides an ultimate description of the system and further theoretical work is needed.