Hartree-Fock simulation of the Ag/MgO interface structure

The atomic and electronic structure of the Ag/MgO interface are calculated using an ab initio Hartree-Fock computer code and a supercell model of a silver monolayer atop three layers of MgO substrate. The band structure, electronic density distribution and densities of states are analysed in detail for isolated and interacting slabs of a metal and MgO. The energetically most favoured adsorption position for Ag atoms is found to be above the O atoms, with the binding energy of 0.20 eV and the equilibrium Ag-O distance of 2.64 Å. Neither appreciable charge transfer in the interfacial region, nor considerable population of bonds between the silver monolayer and the insulating substrate take place. The adhesion energy arises mainly due to the electrostatic interaction of substrate atoms with a complicated charge redistribution in the metal monolayer, characterized by large quadrupole moments and electron density redistribution towards the gap position in the middle of the nearest Ag atoms. This could be a reason for the disagreement of all three SCF theories with the phenomenological image interaction model.