Comparison of intermolecular interaction energies from SAPT and DFT including empirical dispersion contributions.

The dispersion correction based on damped atom-atom long-range interaction contributions has been tested for an extended S22 database of intermolecular complexes using density functional theory (DFT) and symmetry adapted perturbation theory (SAPT) to account for the remaining interaction energy contributions. In the case of DFT, the dispersion correction of Grimme (J. Comput. Chem. 2006, 27, 1787) was used, while for SAPT, another damping function has been developed that has been optimized particularly for the database. It is found that both approaches yield about the same accuracy for the mixed-type complexes, while the DFT plus dispersion method performs better for the hydrogen-bridged systems and the SAPT plus dispersion approach is better for the dispersion-dominated complexes if compared with coupled cluster singles-doubles with perturbative triples interaction energies as a reference.