Density functional study of adsorption of molecular hydrogen on graphene layers

Density functional theory has been used to study the adsorption of molecula r H-2 on a graphene layer. Different adsorption sites on top of atoms, bond s and the center of carbon hexagons have been considered and compared. We c onclude that the most stable configuration of H-2 is physisorbed above the center of a hexagon. Barriers for classical diffusion are, however, very sm all. (C) 2000 American Institute of Physics. [S0021-9606(00)70318-7].