ELECTRONIC-STRUCTURE OF SI(100)C(4X2) CALCULATED WITHIN THE GW APPROXIMATION

The electronic structure of the Si(100)c(4 X 2) surface has been calculated using a quasiparticle formalism in which the self-energy is evaluated in the GW approximation. The calculated surface state dispersions and band gaps are in good agreement with experiments. The results support the existence of correlated dimer buckling at room temperature. The equilibrium c(4 X 2) sur-face obtained from total-energy calculations is 0. 14 eV/dimer lower in energy than the 2 X 1 symmetric dimer surface, exhibits a dimer buckling of 0.69 angstrom, and has a surface energy of 1.39 eV/(l X 1).