An entirely new, very general, atomically smooth, and optically symmetry-adapted reconstruction model for the Si(111)-7 x 7 surface was proposed. It consisted of parallel rows of non-touching, π-bonded, hexagonal rings with center atoms and seems to be a realization of a static commensurate phase of a nonlinear lattice. An overwhelming number of experimental findings on the Si(111) surface finds an intuitive, simple, and natural explanation by the model.

New Hexagonal Ring Model for the Reconstruction of the Si(111)-7 x 7 Surface. J.Pollmann: Physical Review Letters, 1982, 49, 1649-53