Surface Potential, Charge Density, and Ionization Potential for Si(111)-a Self-Consistent Calculation

We report three fully self-consistent calculations of the ionization potential, charge density, and surface potential for the Si(111) surface in which the normal coordinates of the outer two planes of surface atoms were allowed to vary. The ionization potential, calculated to be 5.4 eV, and the Fermi energy (relative to the valence-band maximum), calculated to be 0.3 eV, are both relatively insensitive to surface geometry. This is not true of the surface-state bands, which are quite sensitive to surface geometry.