A semi-empirical potential model for calculating interactions between large aromatic molecules and graphite surfaces

In the present paper, we detail a semi-empirical approach to calculate the interaction energy between large polycyclic aromatic hydrocarbon molecules for which a full ab initio calculation is not possible due to their large size. This semi-empirical and dispersion (SE-D) approach is based on a self-consistent field interaction energy calculation at the semi-empirical AM1, PM3, or MNDO level of approximation for the electrostatic contribution, added to an empirical dispersion term. The coefficients of this dispersion contribution are determined by fitting the equilibrium energies and distances of a large set of polycyclic aromatic hydrocarbon (PAHs) complexes to data available in the literature. We show that this SE-D potential is sufficiently transferable and accurate to calculate in a proper way the interaction energy between large systems such as, for example, the benzene molecule adsorbed on graphite.