Modeling the formaldehyde-graphene interaction using a formaldehyde-pyrene system

Study of the dynamics of H2CO confined within graphene sheets and sensing of H2CO by graphene require an analytic representation of the intermolecular potential between H2CO and graphene. To develop an intermolecular potential for H2CO interacting with graphene, ab initio calculations were performed at the MP2/MG3S, B97-D/MG3S and LPNO-CEPA/1/CBS levels of theory using H2CO-pyrene as a model. The intermolecular interactions were computed for three different orientations of formaldehyde approaching pyrene for a complete description of the interaction. The interaction energy obtained from the MP2, B97-D and LPNO-CEPA/1 methods were compared with the CCSD(T) method. The LPNO-CEPA/ 1/CBS method gives the best interaction energies compared to the CCSD(T)/CBS method. The LPNO-CEPA/1/CBS data obtained is fitted to an analytical potential energy function written as the sum of two-body interactions between the C atoms of pyrene and the C, H, O atoms of formaldehyde. The fitted potential energy function represents the ab initio data in excellent agreement for all the orientations considered. The analytical potential was also found to represent very well the interactions for two new orientations not considered in fitting, emphasizing the global nature of the analytic potential. The new potential is also compared with the van der Waals AMBER model.