(139d) Inferring Transferable Intermolecular Potential Models

Discontinuous molecular dynamics (DMD) is combined with thermodynamic perturbation theory (TPT) to provide an efficient basis for characterizing molecular interactions based on vapor pressure and liquid density data. Several prospective potential models are discretized to permit treatment by Barker-Henderson perturbation theory. The potentials are characterized by 11 wells ranging over radial distances from the site diameter to three times that diameter. Considered potential models include the Lennard-Jones, square-well, Yukawa, and multi-line potentials, and their combinations. The optimal model is found to be a combination of square-well and Yukawa potentials, with the switch position and Yukawa decay set to universal values. The Lennard-Jones (LJ) potential provides competitive accuracy however. Considering statistical information criteria facilitates the identification of the optimal model. This finding sets the stage for developing a consistent mapping between, say, continuous LJ potentials and Step LJ potentials. The Step LJ potentials can be optimized and refined globally and rapidly by the DMD/TPT methodology and applied to continuous LJ potentials through the mapping.