Cl chemisorption on the Ag(001) surface: Geometry and electronic structure

Abstract

Simple overlayer and mixed-layer geometries are studied for the observed $c(2\mathrm{}\times 2)$ structure of atomic Cl adsorbed on the Ag(001) surface. A self-consistent, Gaussian, linear-combination-of-atomic-orbitals technique with a local exchange-correlation potential is used. Reference calculations are performed for bulk Ag, the clean Ag(001) surface, and an isolated $c(2\mathrm{}\times 2)\mathrm{Cl}$ layer. The calculated total and partial density of states for the two geometries are compared with angle-integrated and angle-resolved photoemission experiments. The mixed-layer model gives close agreement with experiment while the overlayer model predicts a single Cl feature above the Ag $d$ band, contrary to the photoemission data. Discrepancies between these calculations and a low-energy electron diffraction study of this system are discussed.