Adsorbate induced changes in surface stress and phonon dispersion curves of chemisorbedsystems

Abstract

We present a summary of theoretical results documenting changes in surface stress andsurface phonon frequencies for selected light gas adsorbates on Ni(001) and Cu(001) which,when compared with experimental data, provide critical information on surface geometryand electronic structure. Our calculations of the surface electronic structure arebased on density functional theory, using the pseudopotential method, while theevaluation of surface dynamics relies on the density functional perturbation theory. Ac(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 inducedsurface stress change depends on the height at which the adsorbate sits on the surface, it isnot a direct measure of the propensity of the substrate to reconstruct. We alsoconsider examples of changes in surface electronic structure, and surface force fieldsand hence the characteristics of surface phonon dispersion curves, brought aboutby chemisorption, and compare them with experimental data where available.