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

Abstract

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 of 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.