Adsorption of closed-shell molecules on metallic surfaces: Capabilities and limitations of density functional theory

By means of density functional theory (DFT), we study the electronic structure of a benzene molecule on a (1 1 1) oriented Au surface, which is a prototypical system for closed-shell molecules adsorbed on non-reactive metallic surfaces. We show that the electronic structure of such a system is well described by the DFT approach. An inclusion of the van der Waals interaction is important only for structural details. Fixing the structure by other means, the method therefore provides adequate results for the charge density as well as the density of states.