First principles study of the electronic and geometric structure of Cu(5 3 2)

Using density functional theory with the generalized gradient approximation and ultra-soft pseudo-potentials, we have calculated structural relaxations of the Cu(5 3 2) surface which contains steps and kinks. We find the relaxation pattern to oscillate dramatically for atoms in the first 10 layers before decaying rapidly in the bulk. The most striking feature is an outward expansion of the relative interlayer separation d12 of 25%. We also find serious discrepancies with relaxation pattern and relaxation amplitudes calculated using embedded atom method potentials that may reflect the limitation of these potentials to accurately describe systems with complex geometries. Full potential calculations reveal a dispersionless surface state along a high symmetry direction in the surface Brillouin zone. Valence charge density along several planes show excess of charge around kink atom and the nature of bonding with other (5 3 2) atoms.