The Stillinger-Weber potential was used to calculate the interaction energy between pairs of missing dimer vacancies upon the (100) surface. It was found that there was a long-range repulsion between 2 missing dimer vacancies that were located in the same dimer row, while there was a slight attraction between missing dimer vacancies in adjacent rows. The results were used to model the collective equilibrium properties of ensembles of vacancies. At low temperatures and high concentrations, the vacancies self-organized into long wavy lines that were perpendicular to the dimer rows. During heating, these lines broke up so as to form a so-called gas of short and almost linear aggregates which consisted of several vacancies. At an even higher temperature, the vacancies tended to form pairs which served as nuclei for the formation of so-called vacancy islands.

P.C.Weakliem, Z.Zhang, H.Metiu: Surface Science, 1995, 336, 303-13