MgO/Ag interface structure and STM images from first principles

The interface of MgO/Ags001d has been studied with density functional theory applied to slabs. We havefound that regular MgO films show a small adhesion to the silver substrate, the binding can be increased inoff-stoichiometric regimes, either by the presence of O vacancies at the oxide film or by a small excess of Oatoms at the interface between the ceramic to the metal. By means of theoretical methods, the scanningtunneling microscopy signatures of these films is also analyzed in some detail. For defect free depositscontaining 1 or 2 ML and at low voltages, tunnelling takes place from the surface Ag substrate, and at largepositive voltages Mg atoms are imaged. If defects, oxygen vacancies, are present on the surface of the oxidethey introduce much easier channels for tunnelling resulting in big protrusions and controlling the shape of theimage, the extra O stored at the interface can also be detected for very thin films.