Optical fingerprints of Si honeycomb chains and atomic gold wires on the Si(111)-(5x2)-Au surface

The intensively studied Si(111)-(5x2)-Au surface is reexamined using reflectance anisotropy spec-troscopy and density functional theory simulations. We identify distinctive spectral features relatingdirectly to local structural motifs such as Si honeycomb chains and atomic gold wires that are commonlyfound on Au-reconstructed vicinal Si(111) surfaces. Optical signatures of chain dimerization, responsiblefor the observed (x2) periodicity, are identified. The optical response, together with STM simulations andfirst-principles total-energy calculations, exclude the new structure proposed very recently based on thereflection high-energy electron diffraction technique analysis of Abukawa and Nishigaya [Phys. Rev. Lett.110, 036102 (2013)] and provide strong support for the Si honeycomb chain with the triple Au chainmodel of Erwin et al. [Phys. Rev. B 80, 155409 (2009)]. This is a promising approach for screeningpossible models of complex anisotropic surface structures.