GEOMETRY AND ELECTRONIC BAND-STRUCTURE OF GAAS(110)-BI (1 ML)

We present a robust method for a self-consistent solution of the Kohn- Sham equations for both the electronic and ionic degrees of freedom. T he solution is based on a supercell technique with local-density-funct ional pseudopotential theory. From a given initial set of atomic posit ions, a conjugate gradient technique is used to achieve the equilibriu m geometry by moving along the Born-Oppenheimer subspace. The algorith m is applied to both the clean (110) GaAs surface, and to the adsorpti on of an ordered monolayer of Bi on the GaAs(110) surface. The calcula ted relaxed geometries are compared with recent low-energy electron-di ffraction results, and the electronic band structures are compared wit h both angle-resolved-photoemission studies and high-resolution electr on-energy-loss measurements.