HARTREE-FOCK SIMULATION OF THE AG MGO INTERFACE STRUCTURE/

The atomic and electronic structure of the Ag/MgO interface are calcul ated using an ab initio Hartree-Fock computer code and a supercell mod el 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 a nd the equilibrium Ag-O distance of 2.64 Angstrom. Neither appreciable charge transfer in the interfacial region, nor considerable populatio n of bonds between the silver monolayer and the insulating substrate t ake place. The adhesion energy arises mainly due to the electrostatic interaction of substrate atoms with a complicated charge redistributio n in the metal monolayer, characterized by large quadrupole moments an d electron density redistribution towards the gap position in the midd le of the nearest Ag atoms. This could be a reason for the disagreemen t of all three SCF theories with the phenomenological image interactio n model.