The adsorption and diffusion of Au(SCH3)2 complexes as well as bare SCH3 radicals on the unreconstructed Au(111) surface were studied using density-functional theory. Maksymovych et al. observed these complexes at the Au(111) surface by scanning tunnelling microscopy. In accordance with previous density-functional theory studies by other groups, a slight energetic preference was found for the bonding of SCH3 on the surface in Au(SCH3)2 complexes. The net energy gain accounting for the creation of one Au adatom amounts to approximately 0.2eV per SCH3 radical. The diffusive motion of these complexes includes rotational and translational diffusion steps with energy barriers of 0.44 and 0.37eV, respectively. It was speculated whether this could result in a correlation of the direction of consecutive diffusion events. In case of bare SCH3 radicals, a diffusion barrier of 0.26eV was calculated.

Adsorption and Diffusion of SCH3 Radicals and Au(SCH3)2 Complexes on the Unreconstructed Au(111) Surface in the Submonolayer Coverage Regime. A.Franke, E.Pehlke: Physical Review B, 2009, 79[23], 235441