Vacancy formation on the GaAs(111) surface was calculated to be strongly exothermic in character. The creation of one vacancy in each 2 x 2 cell allows the remaining Ga surface atoms to have a large inward relaxation, resulting in a 2.3eV reduction in energy. It also transformed the polar (111) surface into a non-polar (110)-like surface. The calculations provide strong support for the vacancy model of Tong et al., which was determined from analysis of low-energy-electron-diffraction data.

Vacancy-Induced 2 x 2 Reconstruction of the Ga(111) Surface of GaAs. D.J.Chadi: Physical Review Letters, 1984, 52, 1911-4