Long-ranged adsorbate-adsorbate interactions mediated by a surface state band

J. Phys.: Condensed Matter 12, L13 (2000)

P. Hyldgaard and M. Persson,
Department of Applied Physics, Chalmers/Göteborg University, S-412 96 Göteborg, Sweden

Abstract

The adsorbate-adsorbate interaction mediated by Shockley-surface states on, e.g. the (111) faces of noble metals, yields a oscillatory form modulated by a d-2 envelope at asymptotoc adsorbate separations d. For this interaction we obtain a nonperturbative analytical estimate, specified by experimentally accessible Shockley-state parameters and the finite Fermi-level phase shift, which characterize the standing-wave patters observed in scanning tunneling microscopy (STM) images. We provide explicit interaction results for the phase shift value suggested by STM measurements of sulphur adsorbates on Cu(111), and we attempt to relate our results to corresponding observations of correlations in the adsorbate distribution function.