X-ray absorption spectra at the Ca L2,3 edge calculated within multichannel multiple scattering theory -: art. no. 245120

We report a theoretical method for x-ray absorption spectroscopy (XAS) in condensed matter which is based on the multichannel multiple scattering theory of Natoli et al. and the eigen-channel R-matrix method. While the highly flexible real-space multiple scattering (RSMS) method guarantees a precise description of the single-electron part of the problem, multiplet-like electron correlation effects between the photoelectron and localized electrons can be taken account for in a configuration interaction scheme. For the case where correlation effects are limited to the absorber atom, a technique for the solution of the equations is devised, which requires only little more computation time than the normal RSMS method for XAS. The method is described and an application to XAS at the Ca L-2,L-3 edge in bulk Ca, CaO, and CaF2 is presented.