Strengths of plasmon satellites in XPS: Real-time cumulant approach

Abstract

Plasmon satellites observed in x-ray photoemission spectra (XPS) reflect many-body effects beyond the single-electron approximation. However, theoretical calculations are challenging and simplified theories based on electron gas models are not always satisfactory. Here, a cumulant Green’s function approach with a real-time time-dependent density functional theory calculation of the cumulant is described for calculations of these effects, without the need for adjustable parameters. The approach yields good agreement with experimental XPS results, as illustrated for Ge and Al. Corrections due to extrinsic losses and interference are also briefly discussed.