Surface Strain Effects on the Adsorption of Au Adatoms on MgO(001) Surfaces with Surface O Vacancies

By employing ab-initio total-energy and electronic-structure calculations based on the density-functional theory, we studied the effects of surface strain ε_s on the adsorption properties of a Au adatom on defective MgO(001) surfaces with surface oxygen vacancies (F_s centers). The formation energy of the F_s center on MgO(001) varied very slightly in the region of ε_s from −6% to −4% and monotonically decreased with the increase in ε_s, from −4% to +6%. As ε_s increased, the adsorption energy (EadsFS) of Au on the ε_s center of strained MgO(001) monotonically decreased and, in particular, showed a much larger decrease in EadsFS for a tensile surface strain of ε_s > +4%. The surface strain dependence on the physical properties, such as the charge states, the spatial charge rearrangement, for Au on the F_s center of strained MgO(001) surfaces was also analyzed. These results provide important physical information on the effects of surface strain on the adsorption of Au on MgO(001) surfaces with F_s centers.