Calculations off second-harmonic generation for a jellium metal surface

The microscopic a parameter, which alone is needed to describe the surface sensitive dependence of second-harmonic generation from jellium metals, is calculated within a time-dependent local-density-functional approximation for frequencies between zero and twice the bull; plasmon. The calculations incorporate an extrinsic damping and allow for the excitation of bulk plasmons. The results for frequencies up to half the bulk plasmon are very similar to earlier evaluations, while at higher frequencies only weak spectral structure is found.