Simulating Cl K-edge X-ray absorption spectroscopy in MCl6 2- (M = U, Np, Pu) complexes and UOCl5 - using time-dependent density functional theory

We report simulations of the X-ray absorption near edge structure at the Cl K-edge of actinide hexahalides MCl6 (2-) (M = U, Np, Pu) and the UOCl5 (-) complex using linear response time-dependent density functional theory extended for core excitations. To the best of our knowledge, these are the first calculations of the Cl K-edge spectra of NpCl6 (2-) and PuCl6 (2-). In addition, the spectra are simulated with and without the environmental effects of the host crystal as well as ab initio molecular dynamics to capture the dynamical effects due to atomic motion. The calculated spectra are compared with experimental results, where available and the observed trends are discussed.