Total-energy calculations were performed for a series of (2 x 4) and (4 x 2) reconstructed (001) surfaces which had not been considered by previous theoretical studies. A (2 x 4) surface model which contained single anion dimers in the first and third atomic layers was predicted to give a balanced surface stoichiometry. It was more stable than the two As-dimer α structure, which had been proposed previously, due to its lower electrostatic energy. The results for the (4 x 2) reconstructed surface supported a two Ga-dimer β2 structure which had been proposed. Mixed Ga-As dimers, adsorbed on a Ga-terminated substrate, were almost degenerate in energy.

Surface Phase Diagram of (2x4) and (4x2) Reconstructions of GaAs(001). W.G.Schmidt, S.Mirbt, F.Bechstedt: Physical Review B, 2000, 62[12], 8087-91