A simple lattice gas model was proposed for semiconductor (111) surface reconstruction. By signing energy parameters to the gas particles and the interaction among them it was found that the local structure for the silicon (111) surface (7 x 7) reconstruction and the germanium (111) surface c(2 x 8) reconstruction should be different, and that the formation of the dimers on the surfaces plays a very important rule in the surface reconstructions. It was suggested that a dimer instead of a simple adatom should be the basic building unit for the germanium (111) surface c(2 x 8) reconstruction.

Lattice Gas Model for Semiconductor (111) Surface Reconstruction. Y.G.Hao, L.M.Roth: Surface Science, 1990, 232[1-2], L201-4