Real-space Green's function approach for intrinsic losses in x-ray spectra

Abstract

Intrinsic inelastic losses in x-ray spectra originate from excitations in an interacting electron system due to a suddenly created core-hole. These losses characterize the features observed in x-ray photoemission spectra (XPS), as well Here we present a complementary {\it ab initio} real-space Green's function (RSGF) generalization of the Langreth cumulant in terms of the dynamically screened core-hole interaction $W_c(\omega )$ and the independent particle response function. We find that the cumulant kernel $\beta (\omega )$ is analogous to XAS, but with the transition operator replaced by the core-hole potential with monopole selection rules. The behavior reflects the analytic structure of the loss function, with peaks near the zeros of the dielectric function, consistent with delocalized quasi-boson excitations. The approach simplifies when $W_c(\omega )$ is localized and spherically symmetric. Illustrative results and comparisons are presented for the electron gas, sodium, and some early transition metal compounds.

References in corpus (3)

• Accurate X-Ray Absorption Predictions for Transition Metal Oxides: An Advanced Self-Consistent-Field Approach Inspired by Many-Body Perturbation Theory
• Real time cumulant approach for charge transfer satellites in x-ray photoemission spectra
• Non-linear response in the cumulant expansion for core hole photoemission