CH-{π} interaction-induced deep orbital deformation in a benzene-methane weak binding system

The nonbonding interaction between benzene and methane, called CH-{\pi} interaction, plays an important role in physical, chemical, and biological fields. CH-{\pi} interaction can decrease the system total energy and promote the formation of special geometric configurations. This work investigates systemically the orbital distribution and composition of the benzene-methane complex for the first time using ab initio calculation based on different methods and basis sets. Surprisingly, we find strong deformation in HOMO-4 and LUMO+2 induced by CH-{\pi} interaction, extending the general view that nonbonding interaction does not cause orbital change of molecules.