Dynamical calculations of X-ray absorption and emission spectra

The authors have previously shown that one-particle calculations of X-ray spectra in simple metals give very different results depending on whether the core hole is taken into account or not. Guided by experiment and the dynamical theory of X-ray spectra developed by Nozieres and DeDominicis (ND) (1969) the authors have, however, also established the rule that rather realistic spectra can be obtained from a one-particle calculation provided final state wavefunctions are used in the transition matrix elements. They report on direct numerical evaluations of the dynamical ND theory for several different cases including the case where a bound state appears. In all cases the results support their final state rule. They also give arguments in support of the procedure used to extract threshold exponents and asymmetry indices from X-ray absorption and emission spectra and X-ray photoemission spectra.(18 refs)