A first-principle approach to X-ray scattering from solids

Abstract

In this work we have developed a first-principle nonrelativistic many-body theory of X-ray scatterings based on general scattering theory developed by Almbladh and Hedin, which allows renormalization of decaying and inelastic interaction. We separately discuss elastic and inelastic, also non-resonant and resonant X-ray scatterings. In particular the resonant X-ray scatterings are carefully studied beyond the conventional second order perturbation theory to investigate the lifetime of core-hole states on the basis of the sound theoretical background. In the present theory we should classify the stable and the unstable states. The former gives infinitesimal lifetime self-energy whereas the latter gives finite one. We also derive a new formula of the resonant Raman scatterings in terms of two different Green’s functions with different lifetimes where two core levels can contribute, which clearly demonstrate how we can measure lifetime-broadening suppressed X-ray absorption fine structures (XAFS) by use of the resonant X-ray Raman scatterings. Some new aspects of anomalous X-ray scatterings are also discussed by use of the polarization dependence.