Ab initio calculation of self-energy effects on optical properties of GaAs(110)

We present a first-principles calculation of self-energy effects on the opt ical properties of the GaAs(110) surface. Three main results are obtained. (a) The self-energy shifts for the valence bands are larger for surface-loc alized states, at odds with the commonly assumed "scissor operator" hypothe sis. (b) The computed shifts display an almost linear dependence on the sur face localization of the wave function; this allows us to realize a well-co nverged calculation of optical properties based on the GW-corrected spectru m. (c) The agreement with experimental data is improved with respect to loc al-density-approximation calculations.