First-principles theoretical study of alkylthiolate adsorption on Au(1 1 1)

We have studied methylthiolate (MeS), ethylthiolate (EtS), and butylthiolate (BuS) adsorption on the Au(1 1 1) surface using density functional theory within a generalized gradient approximation (GGA). EtS and BuS are also adsorbed at the bridge site slightly off-centered towards the fcc-hollow site and the S–C bond is tilted from the surface normal by 52°. The S 2p core level shift of MeS adsorbed at the bridge site agrees quite well with the experimental results, further supporting the bridge configuration. Finally, we have examined several possible MeS configurations in the c(43×23) superstructure. At present, however, we cannot obtain consistent results with the experimental ones, presumably due to the limited accuracy of the present GGA functional and/or substrate reconstructions.