SURFACE-PLASMON DISPERSION OF AG

The time-dependent density functional approach is used to calculate th e wave-vector dispersion of the surface plasmon of Ag. The 5s conducti on electrons are treated as a semi-infinite homogeneous electron gas a nd the influence of the 4d electrons is described in terms of a polari zable medium. It is shown that the reduction of the s-d screening inte raction in the surface region leads to a positive dispersion of the su rface plasmon in agreement with recent electron energy loss measuremen ts.