Generating phase-shifts and radial integrals for multiple scattering codes

International audience; A brief derivation of the cross section in the independent particle approximation for some of the spectroscopies treated in the msspec program package is presented. We solve the related Schrödinger equation with a complex energy-dependent effective potential in the framework of multiple scattering theory to write the cross-section for photoemission and photoabsorption in a physically transparent way that provides insight in their interpretation and analysis. Relativistic corrections are also implemented. In order to be able to apply this theory to a wide variety of systems we use a kind of all-purpose optical potential, depending only on the local density of the system under investigation, and discuss its merits and drawbacks. A Green’s function approach is shown to be necessary to write the photoabsorption cross section in the case of complex potential. © 2018, Springer International Publishing AG, part of Springer Nature.