Methane adsorption on graphene from first principles including dispersion interaction

The methane-graphene interaction is studied using density functional theory complemented with a semiempirical dispersion correction scheme (DET-D), an oh initio van der Waals density functional (vdW-DF) ansatz as well as using Moller Plesset perturbation theory (MP2). The adsorption energy of 0.17 eV and the molecular distance of 3.28 angstrom obtained from the MP2 calculations are close to the experimental data, while the vdW-DF scheme results either in a realistic adsorption energy or a realistic adsorption geometry, depending on the underlying exchange-correlation functional. The present implementation of DFT-D overbinds about as much as bare DFT calculations underbind, but yields a meaningful adsorption height. (C) 2011 Elsevier B.V. All rights reserved.