DYNAMIC IMAGE POTENTIAL AT AN AL(111) SURFACE

We evaluate the electronic self-energy Sigma(E) at an Al(111) surface using the GW space-time method. This self-energy automatically include s the image potential V-im not present in any local-density approximat ion for exchange and correlation. We solve the energy-dependent quasip article equations and calculate the effective local potential experien ced by electrons in the near-surface region. The relative contribution of exchange proves to be very different for states above the Fermi le vel. The image-plane position for interacting electrons is closer to t he surface than for the purely electrostatic effects felt by test char ges, and, like its classical counterpart, is drawn inwards by the effe cts of atomic structure.