SURFACE RESPONSE OF AN ELECTRON-GAS CONFINED BY A PARABOLIC BARRIER

The parameters that characterize the surface screening response of an electron gas can be exactly found if the electron gas in a jellium model is confined by a barrier whose unscreened form is parabolic, as occurs when the electron gas is embedded in an excess of positive, uniform background charge, forming a wide parabolic quantum well. We obtain for the linear response d(perpendicular to) - d(parallel to) = 0 and at the second harmonic a = -2, independent of driving frequency and bulk density.