Atomic and electronic structures of the Rb-C(1Â 0Â 0) chemisorption system

First-principles calculations based on DFT-GGA method have been performed on Rb adsorption on C(1 0 0)(2×1) surface. The optimized geometries, adsorption energies have been obtained and the preferred binding sites have been determined for the coverage (Θ) of one monolayer and half a monolayer. The calculated results have shown that Rb adsorbate preferred to occupy valley-bridge sites at the coverage of 0.5 ML. At higher coverage of 1 ML, two Rb adsorbates were found to reside in pedestal site and valley-bridge site, respectively. It was also found that when Rb was adsorbed on C(1 0 0)(2×1) surface the work function decreases linearly with increasing coverage and reaches a minimum at Θ=0.5 ML, at higher coverage, the work function is increased again, which may be caused by depolarization effect of the adsorbate. The adsorption behavior was found to be similar to that of Rb on Si(0 0 1) and Ge(0 0 1) surface.