Ab InitioCalculation of Self-Energy Effects on Optical Properties of GaAs(110)

We present a first-principles calculation of self-energy effects on the optical properties of the GaAs(110) surface. Three main results are obtained. (a) The self-energy shifts for the valence bands are larger for surface-localized states, at odds with the commonly assumed ``scissor operator'' hypothesis. (b) The computed shifts display an almost linear dependence on the surface localization of the wave function; this allows us to realize a well-converged calculation of optical properties based on the $\mathrm{GW}$-corrected spectrum. (c) The agreement with experimental data is improved with respect to local-density-approximation calculations.