First-principles pseudopotential total-energy and electronic-structure calculations are reported for two Si(111)(√3 × √3 ):Si adatom geometries. Based on these calculations, a theory of the electronic structure of Si(111)(7×7) is formulated, and the binding energy of Si adatoms on Si(111) is determined.

• Received 31 March 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.154