Toward a Separate Reproduction of the Contributions to the Hartree-Fock and DFT Intermolecular Interaction Energies by Polarizable Molecular Mechanics with the SIBFA Potential.

Following recent refinements of the SIBFA intermolecular potential to the multipolar electrostatic contribution by inclusion of an explicit 'penetration' component, the short-range repulsion term is augmented with a S(2)/R(2) component. The SIBFA potential, and the behaviors of its individual contributions encompassing polarization and charge transfer, were evaluated in a diversity of hydrogen-bonded complexes as well as in a model stacked complex by comparisons with results from ab initio quantum-chemical (QC) computations with energy decomposition. Close agreements between SIBFA and QC results are found on both the interaction energies and their contributions. Extensions to computations at the DFT level are also presented.