I want to use pwscf for the calculation of theoretical XES spectra for some materials (SiO2, Si3N4 and others) where it is not always possible to use simple model of one predominant transition type -for example, in Si L2,3 spectra (transition to Si 2p states) both Si 3S and Si 3D states make contribution. Even worse, some results indicate that non-local transitions are also non-negligible.
So i need to explicitly calculate dipole matrix element for this transition. Could somebody point me to some theoretical background, specific for planewaves and pseudopotentials? Thanks in advance.
