DENSITY-FUNCTIONAL AND QUASI-PARTICLE CALCULATIONS ON THE GAP(110) SURFACE

We describe a method for calculating quasiparticle band structures at semiconductor surfaces. The method uses a simple model which includes contributions from electronic interaction with surface plasmons in add ition to both local field and dynamic effects. Starting with a local d ensity pseudopotential calculation for the GaP(110) surface as a basis , the quasiparticle states are calculated with a minimum of further co mputation. We observe quantitatively different quasiparticle correctio ns for the surface states as compared to those for bulk-like states. N otably, the lowest unoccupied surface state is pushed further up into the projected bulk conduction bands while the occupied surface states are lowered, in line with simple ideas of band gap broadening at free surfaces.