Self-consistent optical potential for atoms in solids at intermediate and high energies

We develop an approximation for the optical potential in a solid valid at i ntermediate and high energies, say, energies from 50 eV and larger. The app roximation builds on the GW expression. We separate the random phase approx imation polarization propagator in a core electron and a valence electron p art, and then have a corresponding separation of the optical potential. For the valence electron optical potential we use a local density approximatio n because the charge density changes fairly slowly, whereas we use a nonloc al optical potential for the core electron part. We apply this method to el ectron-Ar and -Kr elastic scattering, and also to electron scattering from atoms in van der Waals solids, semiconductors, and metals. We find satisfac tory agreement with the observed results. We also study the importance of u sing a nonlocal potential for the core part and the sensitivity to a parame ter, the average excitation energy. We compare the present results with tho se calculated by the Hartree-Fock, Dirac-Hara, and Hedin-Lundqvist potentia ls. The Hedin-Lundqvist potential is rather good for the description of lar ge-angle scattering, whereas none of the local potentials can describe smal l-angle scattering well.