Ab initio calculation of the reflectance anisotropy of GaAs(110)

We compute the optical properties of the (110) surface of gallium arsenide within the first-principles density-functional theory local-density approximation scheme, using norm-conserving pseudopotentials. Starting from the surface electronic structure calculation, we analyze the imaginary part of the theoretical dielectric function, separating surface and bulk contributions. The effects of the nonlocality of the pseudopotential are studied, by working both in the transverse gauge (neglecting them) and in the longitudinal gauge (where they are automatically included). The two calculations, although giving different dielectric functions, yield the same reflectance anisotropy, which compares well with experimental data and with previous theoretical results.