First Principles Theory of Semiconductor Surface State Energies.

The quasiparticle surface state energies are evaluated for semiconductor surfaces using a self energy approach which incorporates many-body effects due to the electron-electron interaction. Quantitative results are presented for the prototypical Si (111):As and Ge(111):As surfaces and compared to angle resolved photoemission data as well as scanning tunneling spectroscopy measurements showing excellent agreement. Consequences for calculations based on the local density approximation are discussed.