BETHE-SALPETER EQUATION CALCULATIONS OF RESONANT INELASTIC X-RAY SCATTERING AT THE NITROGEN K EDGE

John Vinson, Terrence Jach, Tim Elam, and Jonathon Denlinger

We present theoretical calculations of resonant inelastic x-ray scattering (RIXS) at the nitrogen K edge of several materials along with direct comparison to experimental results. Our approach is based on a Bethe-Salpeter equation formalism, and our calculations are carried out using an extension of the OCEAN package, including both intermediate and final-state excitonic effects. By building upon a DFT basis we include ground-state effects without system-dependent fitting parameters. Quasi-particle corrections to the valence- and conduction-band states are included through a GW self-energy. We are able to account for the general trends and features seen in experiment. A more ad hoc account of other contributions to the measured spectra, primarily phonon coupling, is attempted, but this highlights some current shortcomings limiting fully ab initio calculations of the near-edge x-ray spectra of extended systems.