Finite-temperature effects on the x-ray absorption spectra of crystalline alumina from first principles

By including phonon-assisted transitions within plane-wave density functional theory methods for calculating the x-ray absorption spectrum (XAS), we obtain Al K-edge XAS at 300 K two crystalline Al2O3 phases. The reproduces pre-edge peak α-Al2O3, which is not visible static lattice level of approximation. Configurations from Monte Carlo sampling γ-Al2O3 phase space correctly describe out three experimental peaks. We show that second arises 1s to mixed s-p and absent in 0 XAS. This letter serves as an insight into electronic origins characteristic peaks alumina crystals.