Adsorbate Induced Changes In Surface Stress And Phonon Dispersion Curves Of Chemisorbed Systems

We present a summary of theoretical results documenting changes in surface stress and surface phonon frequencies for selected light gas adsorbates on Ni(001) and Cu(001) which, when compared with experimental data, provide critical information on surface geometry and electronic structure. Our calculations of the surface electronic structure are based on density functional theory, using the pseudopotential method, while the evaluation of surface dynamics relies on the density functional perturbation theory. A c(2 × 2) overlayer of C on Ni(001) and of N on Cu(001), causes a large change in the surface stress (≈5 N m-1) turning it from tensile to compressive in both cases. We find that while adsorbate induced surface stress change depends on the height at which the adsorbate sits on the surface, it is not a direct measure of the propensity of the substrate to reconstruct. We also consider examples of changes in surface electronic structure, and surface force fields and hence the characteristics of surface phonon dispersion curves, brought about by chemisorption, and compare them with experimental data where available. © IOP Publishing Ltd