Mechanisms of island formation of alkali-metal adsorbates on Al(111)

Abstract

Using density functional theory total-energy calculations we investigate the chemisorption of Na and K alkali metals on the (111) surface of aluminum from very low coverages (\ensuremath{\Theta}=1/16) up to a full monolayer. The calculations predict site changes of the adsorbate atoms, as well as a condensation into islands with increasing coverage. Some processes are activated, which implies a possibly irreversible temperature dependence. This is shown to have important consequences for the coverage dependency of the work function change.