Second-harmonic generation at simple metal surfaces

Abstract

The time-dependent density-functional approach is used to determine the frequency dependence of second-harmonic generation (SHG) at various simple metal surfaces. In particular, the function a(ω) which characterizes the perpendicular surface contribution to the nonlinear polarization is calculated for realistic ground-state density profiles and by taking into account the nonlocal nature of the self-consistent electronic screening response to the applied fields. At the laser frequency of 1.17 eV, the real part of a(ω) is much larger than the imaginary part and is typically 25–100 % larger than in the static limit. Ima(ω) exhibits a feature for 2ω near the threshold for electron emission and a second one for 2ω near 0.8${\omega }_p$, where ${\omega }_p$ is the bulk-plasma frequency.