Ab-initio study of the effects of charging on the adsorption and diffusion of Au2 on MgO(100)

Abstract

By using ab-initio calculations, the adsorption and diffusion properties of charged Au dimers (Au2+ and Au2−) on MgO(100) were investigated and compared with those of the charge-neutral dimer (Au20). The most favored adsorption structure of Au2+ on MgO(100) is the upright dimer on a surface O atom in agreement with that of Au20. The surface diffusion of Au2+ on MgO(100) occurs by the leapfrog process with a barrier height of 0.38 eV lower than that of Au20 (0.66 eV). The most stable adsorption structure of Au2− on MgO(100) is the flat-lying dimer on two surface Mg atoms. The surface diffusion of Au2− on MgO(100) can proceed by the hopping and walking processes with a barrier height in the range of 0.05–0.11 eV, which is much lower than the diffusion barriers of Au2+ and Au20. Furthermore, detailed information on the electronic properties of Au20, Au2+, and Au2− are also presented.