[摘要]：The nonlocal van der Waals density functional approach is applied to calculate the binding of graphene to Ir(111). The precise agreement of the calculated mean height (h) over bar = 3.41 angstrom of the C atoms with their mean height (h) over bar = (3.38 +/- 0.04) angstrom as measured by the x-ray standing wave technique provides a benchmark for the applicability of the nonlocal functional. We find bonding of graphene to Ir(111) to be due to the van der Waals interaction with an antibonding average contribution from chemical interaction. Despite its globally repulsive character, in certain areas of the large graphene moire unit cell charge accumulation between Ir substrate and graphene C atoms is observed, signaling a weak covalent bond formation.
