Excitonic and Local-Field Effects in Optical Spectra from Real-Space Time-Domain Calculations

摘要

We present a novel approach to solve the Bethe-Salpeter equation for the polarisation function. Rather than from the usual eigenvalue representation, the macroscopic polarisability is obtained from the solution of an initial-value problem. This allows for the first time to calculate excitonic and local-field effects in optical spectra of large and complex systems such as surfaces. As an example we investigate the optical anisotropy of the hydrogen-passivated Si(110) surface. It is shown that the electron-hole attraction is largely responsible for the peculiar line shape of the surface optical spectrum.