THEORETICAL CALCULATIONS OF THE SCANNING-TUNNELING-MICROSCOPY IMAGES OF THE SI(111)-SQUARE-ROOT-3X-SQUARE-ROOT-3-AG SURFACE

The scanning-tunneling-microscopy (STM) images of the Si(111) square-root 3 X square-root 3-Ag surface have been calculated from first principles for a structural model of the surface recently proposed, or the modified honeycomb-chained-trimer model, which is consistent with reported photoemission and inverse-photoemission spectra. The results show excellent agreement with reported STM images. Each bright spot corresponding to a protrusion in the reported STM images represents neither Ag nor Si atoms but rather corresponds to the center of each surface Ag trimer.