It was pointed out that, on the reconstructed (111) surface, the uppermost atoms occupied both hexagonal close-packed and face-centered cubic sites. By using first-principles calculations to deduce the surface energies of the system, with the top Au layer occupying face-centered cubic, hexagonal close-packed, top, or bridge sites, it was found that the hexagonal close-packed site was only 1mRy per surface atom higher in energy than the face-centered cubic site. The complex (111)Au reconstruction was re-examined by means of a 2-dimensional Frenkel-Kontorowa technique. The surface band structure of the (111) surface along high-symmetry lines in the surface Brillouin zone was calculated, with the top layer occupying face-centered cubic, hexagonal close-packed, or bridge sites. It was found that the surface electronic structure was almost independent of the position of the top layer.

N.Takeuchi, C.T.Chan, K.M.Ho: Physical Review B, 1991, 43[17], 13899-906