The bonding of N2 to models of a (9, 0) carbon nanotube and graphite

We have studied the bonding of N2 to a (9, 0) carbon nanotube using the MP2 and ONIOM methods with extended basis sets. We find a weak dispersion type bond with the N2 ∼3.3 Å away from the surface. Our best estimate of the binding energy, including the effect of expanding the high accuracy piece from ethylene to cluster A, is 1.88 kcal/mol for bonding in a twofold site and 1.97 kcal/mol for bonding in a sixfold site. We find N2 is bound more strongly to a graphitic surface by ∼0.3 kcal/mol.