2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/29416We prove, by realistic microscopic calculations within the sp^3s^* Tight Binding method for GaAs (110) and (100), that the surface optical properties are not influenced by long-range crystal termination effects, and hence that they can be consistently studied considering slabs of limited thickness (20 - 30 Å). The origin of derivative-like and bulk-like lineshapes in Reflection Anisotropy Spectra is also discussed, analyzing the effects arising from possible surface-induced reduction, broadening, and shifting of the bulk spectrum near the surface.10 figures. In press in Physical Review B, scheduled 15 Aug. 1999Condensed Mattertext