Nitrogen gas on graphene: Pairwise interaction potentials

We investigate different types of potential parameters for the graphene-nitrogen interaction. Interaction energies calculated at DFT level are fitted with the semi-emperical Improved Lennard-Jones potential. Both a pseudo-atom potential and a full atomistic potential are considered. Furthermore, we consider the influence of the electrostatic part on the parameters using different charge schemes found in the literature as well as optimizing the charges ourselves. We have obtained parameters for both the nitrogen dimer and the graphene-nitrogen system. For the former, the four-charges Cracknell scheme reproduces with high precision the CCSD(T) interaction energy as well as the experimental diffusion coefficient in both the pseudo-atom and full atomstic potential. In the second case, the atom-atom model provides an average interaction energy of 2.3 kcal/mol, comparable with the experimental graphene- N2N2 interaction of 2.4 kcal/mol.