Many-body calculation of surface states: As on Ge(111)

Abstract
A first-principles theory of the quasiparticle surface-state energies is given. The electron self-energy operaor is evaluated with inclusion of both local fields and dynamical screening effects in a surface calculation using a repeated slab geometry. The results for the prototypical Ge(111):As surface are in excellent agreement with recent angle-resolved photoemission data and show a substantially larger gap between the empty and occupied surface states in comparison to local-densityfunctional calculations. Implications for local-densityfunctional calculations of surface-state energies in semiconductors are discussed.