Density functional study of adsorption of molecular hydrogen on graphene layers

Density functional theory has been used to study the adsorption of molecular H2 on a graphene layer. Different adsorption sites on top of atoms, bonds and the center of carbon hexagons have been considered and compared. We conclude that the most stable configuration of H2 is physisorbed above the center of a hexagon. Barriers for classical diffusion are, however, very small.