Analytic potential energy functions for benzene–water interactions based on accurate <i>ab initio</i> calculations and the ghost atom formalism

This article reports the, so far, best interaction potential energy between benzene and water with analytical function. The accurate intermolecular potential energy of the C₆H₆-H₂O system is calculated from electronic structure theory. The calculations are done at the MP2 level of theory, considering the aug-cc-pVTZ basis set, and the results are comparable with CCSD(T) at the complete basis set (CBS) limit. The <i>ab initio</i> calculations are performed for nine different orientations. The <i>ab initio</i> potential energy points are then well-fitted to a modified Buckingham-type analytic function with atom-atom and ghost atom-atom interactions. The ghost atom position is situated at the center of the benzene ring. An analytical derivation for calculating the potential energy gradient is provided for the ghost atom model and the use of molecular dynamics.