ELASTIC PHOTON SCATTERING AND PHOTOEFFECT BY K-SHELL ELECTRONS IN NEUTRAL ATOMS *

A screening model based on nonrelativistic Hartree-Fock central field is elaborated for the K-shell Rayleigh amplitudes and the total photoeffect cross section. It is valide in a large energy range from a few hundred eV up to hundreds of keV for intermediate and large atomic numbers. Multipoles, retardation as well as relativistic kinematics effects are taken into account. A good agreement with full relativistic numerical calculations is found.