Cumulant Green’s function calculations of the asymmetry of 4f_7/2peaks in the XPS of Au and Pt

Measurements of the 4f_7/2 quasi-particle peaks in the XPS of Au and Pt exhibit asymmetries which have been attributed to edge singularity effects in the spectral function. The goal of this work is to model these asymmetries using real-time TDDFT calculations of the low energy particle-hole excitation spectrum. In our approach a cumulant Green’s function is used to calculate the shift in spectral weight from the quasi-particle peak to the satellite features that account for the asymmetry. The cumulant is calculated using a real-time TDDFT formalism using an extension of the SIESTA code base. The computational workflow is carried out using Corvus, a recently developed python-based workflow management tool designed to integrate multiple scientific software packages. This implementation is efficient and allows for a post-processing analysis appended to the original workflow. Our calculations fit to Doniach-Sunjic line shapes are in good agreement with the experimental XPS data for Au and Pt.