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arXiv · 2606.09440

First-principles description of pumped inelastic X-ray scattering: example of K-edge RIXS in graphite

Elias Richter·Benedikt Maurer·Claudia Draxl
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Abstract

We present an $\textit{ab initio}$ framework for predicting resonant inelastic X-ray scattering (RIXS) in optically pumped materials. Our methodology is based on the Kramers-Heisenberg formula for the double-differential cross section formulated using the results of the Bethe-Salpeter equation (BSE) from many-body perturbation theory. To extend this approach to the time domain, we incorporate non-equilibrium charge-carrier distributions obtained from real-time, time-dependent density-functional theory (RT-TDDFT). Generalizing the RIXS implementation with respect to arbitrary polarizations, allows us to consider different orientations of incoming and outgoing light. We demonstrate our method's capabilities by studying RIXS at the K-edge of graphite for various non-equilibrium charge-carrier distributions, representing different delay times after optical pumping. Our results reveal angular dependencies in $\pi$- and $\sigma$-orbital-derived spectral regions, in good agreement with experiment.

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Elias Richter, Benedikt Maurer, Claudia Draxl. 2026-06-08. First-principles description of pumped inelastic X-ray scattering: example of K-edge RIXS in graphite. https://arxiv.org/abs/2606.09440

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