Toward an Accurate Description of Methane Physisorption on Carbon Nanotubes

We present a high-level ab initio investigation of the effects of model size and curvature on the exterior and interior binding energy of methane on single-walled carbon nanotubes. The interaction energies of methane with curved coronene were computed using complete basis set MP2 with a CCSD(T) correction. A variety of novel dispersion-including density functional approaches were then compared to the benchmark data. The top-performing functionals were used to calculate binding energies between methane and larger nanotube fragments all the way through infinite nanotubes. The methane binding energy of a narrow (9,0) carbon nanotube, compared to a flat graphene surface, is decreased by 32% on the exterior but increased by 185% on the interior.