Band structure contribution of adsorbed H₂ on graphene calculated from molecular orbital projections


Density functional theory allows for the first-principles calculation of projected wavefunctions onto orthogonalized atomic wavefunctions. Such calculations can be applied to study the bonding of a molecule onto an adsorbing surface. In particular, these projections allow one to identify the contributions of the adsorbed molecule to the band structure of the whole system. In this paper, we consider a system composed of an H2 molecule adsorbed onto the hollow (H) site in a graphene 3x3 supercell. The adsorbed H2 molecule gives rise to two bands roughly 6 eV on either side of the Fermi energy. These bands may be attributed to the hybridization of the H2 bonding and anti-bonding molecular σ orbitals and the graphene bands.