Electron emission diffraction and x-ray absorption in the presence of Coulomb-like potentials: theoretical formulation in the muffin-tin potential approach

Electron emission diffraction and x-ray absorption in the presence of an unscreened excited atom core hole - responsible for a long-range Coulomb force distorting the outgoing electron waves - are described within the muffin-tin potential model by means of the Green's operator multiple-scattering formalism: a case especially relevant for molecules and polyatomic clusters. The approach has the merit of allowing analytical and closed-form expressions to be obtained for all amplitudes and of yielding the possibility of expanding the scattering amplitudes in multiple-scattering terms. The treatment is mathematically consistent avoiding the appearance, in the expanded scattering amplitudes, of terms which are either indefinite or divergent.