Work function of metals upon alkali-metal adsorption: Overlayer relaxation

Abstract

The work function of metals is lowered upon alkali-metal adsorption and this lowering (\ensuremath{\Delta}\ensuremath{\Phi}) is known to be coverage dependent. Using standard jellium-model calculations, we show that if the metal-overlayer distance is assumed to increase with coverage, the experimental behavior of \ensuremath{\Delta}\ensuremath{\Phi} is much better reproduced. In particular the minimum work function is increased and shifted to higher coverages, in agreement with experimental results. The increase of distance with coverage also leads to an energetically more stable configuration.