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 ( Au 2 + and Au 2 − ) on MgO(100) were investigated and compared with those of the charge-neutral dimer ( Au 2 0 ). The most favored adsorption structure of Au 2 + on MgO(100) is the upright dimer on a surface O atom in agreement with that of Au 2 0 . The surface diffusion of Au 2 + on MgO(100) occurs by the leapfrog process with a barrier height of 0.38 eV lower than that of Au 2 0 (0.66 eV). The most stable adsorption structure of Au 2 − on MgO(100) is the flat-lying dimer on two surface Mg atoms. The surface diffusion of Au 2 − 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 Au 2 + and Au 2 0 . Furthermore, detailed information on the electronic properties of Au 2 0 , Au 2 + , and Au 2 − are also presented.