Atomic and electronic structure and interatomic potentials at a polar ceramic/metal interface: {222}MgO/Cu

Local density functional theory (LDFT) calculations, within the plane-wave- pseudopotential framework, are performed for the {222}MgO/Cu polar interfac e, with the objective of elucidating the atomic and electronic structure of the interface, as well as interface interatomic potentials. Calculations a re performed for both coherent interfaces and semicoherent interfaces that approximate the lattice constant mismatch of the true system. Calculations of local electronic density of states and adhesive energies are performed p rimarily for coherent interfaces. The density of electronic states at the i nterface for the oxygen-terminated configuration exhibits a peak in the bul k MgO energy gap that results from O(2p)-Cu(3d) hybridization. The calculat ed interface adhesive energies for coherent interfaces as a function of the interface spacing and translation state are well reproduced by a simple an alytical expression that combines an attractive Rydberg-function term and a repulsive pairwise Born-Mayer potential across the interface. Calculations are performed for a semicoherent interface with 5x5 Cu layer unit cells op posite 4x4 MgO layer unit cells, an approximation to the true system with l attice constant ratio of 7/6, to investigate the relaxation at the interfac e in the presence of misfit. The terminating oxygen layer as well as the in terface Cu layer exhibits warping albeit on a scale of less than 0.1 Angstr om. [S0163-1829(99)12047-2].