Graphyne on metallic surfaces: A density functional theory study

We show how a structural modification of graphene, which gives the carbon allotrope graphyne, can induce an energy gap at the K point of the Brillouin zone. Upon adsorption on metallic surfaces, the same mechanism is responsible for a further modification of energy bands which occurs via the charge transfer mechanism. We perform the calculation based on the density functional theory with the novel nonlocal van der Waals-density functional correlation of the adsorption of graphyne on Cu(111), Ni(111), and Co(0001) surfaces and show the dependence of the band change on the charge transfer in the system. The binding of graphyne appears to be stronger than that of graphene on the same surfaces.