The electronic structure, surface and relaxation energies, and the electric field gradient for the unreconstructed Au(001) surface were calculated by means of the ab-initio all-electron full-potential linearized augmented plane wave slab method. The valence states were calculated within the standard semi-relativistic approach whereas the core states are treated in a fully relativistic way. The Au(001) surface was modelled by free slabs of 5, 7, and 9 layers. From the 9-layer calculation a work function of 5.39 eV was obtained. For the surface energy a value of 1.30 J/m2 for the unrelaxed geometry was derived from the total energies of the 7- and the 9-layer slabs. From total energy minimization of the 7-layer slab, a negative, inward relaxation of -2.6% and a relaxation energy of 14.3 × 10-3 J/m2 were derived. To discuss a mechanism of reconstruction, particular surface states were analyzed in detail in terms of the band structure, layer-dependent density of states and the charge density distribution. Differences of surface and central-layer charge densities show a gain of charge in z-direction localised below and also, to a smaller extent, above the surface atoms. We find a very small gain of delocalised charge in the surface plane between the nearest neighbour positions at the expense of more localised s-d hybridised states. The electric field gradient component Φzz was obtained in a two energy window calculation for which the Au5p states were also treated as band states. The resulting Φzz values are -16.50 × 1017 V/cm2 surface layer, and -3.3 × 1017 V/cm2 for the subsurface layer.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Condensed Matter Physics
- Surfaces and Interfaces