From carbon atom to graphene on Cu(111): an ab-initio study

Graphene growth by chemical vapor deposition on copper is one of the most popular method to obtain large scale sample. If the commensurability of graphene with Cu(111) plays a determinant role, the most stable geometries for the 2D crystal do not correspond to the most stable adsorption sites of individual carbon atoms on the same surface. In this paper, we analyzed this contradiction based on density functional theory calculations. From the three stable sites for isolated carbon atoms on Cu(111), only two of them are involved when small clusters of carbon are adsorbed. However, because of the shift from strong C-Cu interaction for isolated (or unsaturated C atoms) to weak van der Waals C-Cu bonding, other stable geometries are found for adsorbed infinite graphene. We propose here two new stable graphene adsorption geometries and we present a detailed analysis of the various adsorption geometries.