Surface plasmons in a free-electron metal

The dispersion and damping of the surface plasmons are calculated for a free-electron model of Al. At large wave-vector the frequency of the surface plasmons approaches that of the bulk plasmons. Their damping remains quite small up to a wave-vector close to the bulk plasmon cut-off. The change in zero-point energy of the plasmons is calculated, and it gives a large positive contribution to the surface energy.     

Electronic structure and surface reconstruction of adsorbed oxygen on copper(0 0 1)

The electronic structure of the c(2 × 2) and the missing row phases of chemisorbed O on Cu(0 0 1) at a coverage of 0.5 monolayers has been calculated using a full-potential semi-infinite embedding technique. Calculations are made over a range of Cu-O layer spacings, and from the change in the work function, the effective charge on O is obtained. The effective charge is the same for both phases of the O/Cu(0 0 1) surface with a value of −0.3|e| on O, and consequently too small to drive any surface instability. The angular momentum-resolved density of states and energy-resolved charge densities are used to describe the binding and the spatial electronic overlap at the surfaces. In the reconstructed phase the O and the surface Cu atoms undergo displacements, which optimises the bonding.     

The exchange and correlation energy at a metal surface

The change in exchange and correlation energy at a metal surface is calculated in the RPA for the infinite barrier model of a surface. At the electron density of Al, this is + 1350 erg/cm², much less than the values given by approximate solutions of the RPA equations. About half the change in correlation energy comes from the change in plasmon zero-point energy.     

A comment on the surface dielectric sum rule

We show that our ?;-sum rule for the electron response function at a surface is not satisfied in the ?-approximation (semi-classical infinite barrier model), and the recent objection to our procedure by Griffin and Harris is shown to be invalid. Although this approximation is useful for many purposes it does not give a correct result for the plasmon contribution to the surface energy, a fact which is directly connected with its failure to satisfy the ?;-sum rule.     

Plasmon excitation in core-level photoemission

The surface and bulk plasmon satellites in photoemission from a core level are calculated, treating the photoelectron quantum mechanically and including plasmon dispersion. The long wavelength plasmon excitations are suppressed by interference between intrinsic and extrinsic processes, giving featureless satellites at low electron kinetic energy. Structure develops as the electron kinetic energy increases.