Strong-Electric-Field Effect on the Optical-Response Properties of a Metal Surface in p -Polarized Light

We present the first microscopic calculation of nonlocal effects on the optical-response properties of a jellium surface in an applied electric field of the order of 1 V/Å, which is based on a self-consistent density functional calculation of electron density and effective potential. We find drastic field effects on the optical spectra and discuss them in terms of a plasmon excitation in diffuse surfaces. Experiments on nearly-free-electron metals in nonaqueous electrolytes can check our predictions.