# Vibrational Effects in X-ray Absorption Spectra of 2D Layered Materials

## TL;DR

This paper investigates how vibrational coupling and lattice distortions influence X-ray absorption spectra in 2D layered materials, emphasizing the importance of including zero-point motion for accurate spectral interpretation.

## Contribution

It demonstrates the significance of vibrational effects in XANES spectra of 2D materials using advanced many-body perturbation theory including excitonic effects.

## Key findings

- Vibrational effects significantly alter XANES spectra.
- Including zero-point motion improves spectral interpretation.
- Vibrational coupling affects the $\sigma^*$-peak structure.

## Abstract

With the examples of the C $K$-edge in graphite and the B $K$-edge in hexagonal BN, we demonstrate the impact of vibrational coupling and lattice distortions on the X-ray absorption near-edge structure (XANES) in 2D layered materials. Theoretical XANES spectra are obtained by solving the Bethe-Salpeter equation of many-body perturbation theory, including excitonic effects through the correlated motion of core-hole and excited electron. We show that accounting for zero-point motion is important for the interpretation and understanding of the measured X-ray absorption fine structure in both materials, in particular for describing the $\sigma^*$-peak structure.