Calculations on the adsorption of Au to MgO surfaces using SIESTA

Abstract

The SIESTA suite of programs allows periodic density functional theory calculations to be carried out on system sizes of several hundred atoms. Here we make use of this to study the interface between Au and MgO surfaces. Atomic Au on MgO(100) shows preferential binding over surface anion sites, while the binding energy at a surface anion vacancy is significantly higher than on the stoichiometric surface. High index surfaces are used to generate kink site structures representative of extended defects and Au adsorption at these sites has a binding energy intermediate between MgO(100) and the anion vacancy. In contrast Au₁₀ clusters are found to bind more strongly to kink sites than anion vacancies. Bader charge analysis demonstrates that electron transfer occurs from the surface to the Au species in all calculations and the distribution of this charge in the Au₁₀ case is discussed.