Formation and diffusion of S-decorated Cu clusters on Cu(111)

S-decorated Cu trimers are a likely agent of S-enhanced Cu transport between islands on Cu(111). According to ab initio calculations, excellent S bonding to trimer-Cu dangling valence results in an ad- Cu(3)S(3) formation energy of only approximately 0.28 eV, compared to 0.79 eV for a self-adsorbed Cu atom, and a diffusion barrier < or =0. 35 eV.