<i>Ab initio</i> Maxwell-Bloch approach for x-ray excitations in two-dimensional materials

The combination of Maxwell and Bloch equations is an ideal framework to describe ultrafast time-resolved x-ray experiments on an attosecond timescale in crystals. However, broadband experiments such as x-ray absorption near-edge spectroscopy or resonant inelastic x-ray scattering require detailed knowledge of the electronic structure and transition matrix elements. Here, we show how to fill this gap by combining the Maxwell-Bloch formalism with first-principles calculations treating explicitly the core states. The resulting x-ray absorption spectrum recovers key spectral signatures which were missing in previous work relying on a semiempirical tight-binding approach.