Layer Korringa-Kohn-Rostoker technique for surface and interface electronic properties

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Abstract
A technique is presented for embedding planar defects such as interfaces or surfaces in an otherwise perfect crystal. The method is a layer Korringa-Kohn-Rostoker scheme, in which a solid containing the defect is first partitioned into layers of atoms. The scattering properties of each layer are calculated in a partial-wave basis set, using the two-dimensional symmetry assumed to be present in each layer. The layers are subsequently coupled together, in a plane-wave basis, to form a solid. The self-consistent equations for the scattering matrices of semi-infinite bulk regions embedding the defect are solved iteratively, removing the constraint of three-dimensional translational symmetry. Within this formalism, ‘‘supercell’’ and ‘‘slab’’ boundary conditions can also be applied with no extra difficulty. The approach is illustrated in detail for a twin fault in aluminum, for which the microscopic origins of the stacking-fault properties are discussed. Changes in local symmetry and the resulting hybridization of electronic states explain the observed perturbations in the stacking-fault electronic structure.