Self-consistent pseudopotential calculations for Si (111) surfaces: Unreconstructed (1×1) and reconstructed (2×1) model structures

A recently developed method involving self-consistent pseudopotentials has been used to calculate the electronic structure of several Si (111) surface models. The results for (11) unreconstructed, relaxed and unrelaxed surfaces are compared with earlier calculations and discussed in terms of density-of-states curves and charge-density distributions. A fully self-consistent calculation has been carried out for Haneman's (21) reconstructed surface model. It is found that the important experimental results can be understood using this model, and changes in the electronic structure occurring after reconstruction are rationalized on chemical grounds. In particular infrared-absorption measurements, photoemission measurements, and recent angular-dependent photoemission measurements find consistent explanations.