Exact solution of a variety of X-ray probes in the Falicov-Kimball model with dynamical mean-field theory

TL;DR

This paper provides an exact theoretical analysis of various X-ray spectroscopic probes in the Falicov-Kimball model using dynamical mean-field theory, revealing their interrelations and behavior at finite temperatures.

Contribution

It introduces an exact solution framework for core-level X-ray spectra in the Falicov-Kimball model, emphasizing finite-temperature evaluation methods.

Findings

XPS measures core-hole propagator

XANES captures X-ray absorption near-edge spectra

XES reflects emitted light spectra filling the core-hole

Abstract

We examine core-level X-ray photoemission spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and X-ray emission spectroscopy (XES) in the Falicov-Kimball model by using the exact solution from dynamical mean-field theory. XPS measures the core-hole propagator, XANES measures the absorption of X-rays when the core electron is excited to an unoccupied electronic state of the solid, and not emitted, and XES measures the spectra of light emitted as electrons fill the core-hole state created via some form of X-ray excitation. These three spectra are closely related to one another and display orthogonality catastrophe behavior at T=0. We illustrate how to evaluate these spectra efficiently at finite temperature, with a primary focus on the details of XANES.