Surface versus crystal-termination effects in the optical properties of surfaces

We prove, by realistic microscopic calculations within the sp(3)s(*) tight- binding method for GaAs(110) and GaAs(100), that the surface optical proper ties are not influenced by long-range crystal termination effects, and henc e that they can be consistently studied considering slabs of limited thickn ess (20-30 Angstrom). The origin of derivative like and bulklike line shape s 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. [S0163-1829(99)01123-61].