Comparison between Resonant Inelastic X-Ray Scattering and the Dynamical Structure Factor

Momentum dependent resonant inelastic X-ray scattering (RIXS) is an effective probe of many-body excitations. Theoretical and experimental work has shown that under certain circumstances RIXS can be viewed as an approximate probe of the dynamical structure factor $S(q,\omega)$. We perform cluster diagonalization combined with the bi-conjugate gradient stabilized method to model the RIXS spectra and $S(q,\omega)$ for the single-band and multi-orbital Hubbard models. While these two cross sections share some similar features, there are significant quantitative differences, which highlight the qualitative distinction between these two probes.