An alternative model for the Si(111)-Au reconstruction at 2/5 Au coverage was proposed and analyzed using first-principles calculations. This model was based on the structure suggested by Riikonen & Sánchez-Portal (2005), but its periodicity of 5 x 2 was characterized by the removal of one silicon atom from every 5 x 2 super-cell. It was found that this model and that of Erwin (2003) were very close energetically (<0.5meV/Å2). The key features of angle-resolved photoemission measurement and scanning tunnelling microscopy were accounted for in this model. Particularly, the present model reproduces the surface band observed just below the Fermi level. Extra Si adatoms supply electrons that dope this weaker band and cause the system to convert from metallic to insulating, consistent with two-phase findings. The occupation of the silicon adatom on the parent surface was calculated to be at most one adatom per two 5 x 2 unit cells, in agreement with experiment.

First-Principles Study of the Atomic and Electronic Structure of the Si(111)-(5 x 2)-Au Surface Reconstruction. C.Y.Ren, S.F.Tsay, F.C.Chuang: Physical Review B, 2007, 76[7], 075414 (6pp)