Analysis of the performance of DFT-D, M05-2X and M06-2X functionals for studying π⋯π interactions

The performance of a variety of DFT-D functionals with empirical dispersion correction (B97-D, PBE-D, B-LYP-D, BP86-D) and specialized functionals for the treatment the non-covalent interactions (M05-2X, M06-2X) has been evaluated on four representative groups of complexes with π⋯π interactions: (1) dispersion–dominated complexes taken from the S22 database; (2) complexes with eclipsed planar polycyclic aromatic hydrocarbons, PAHs; (3) complexes with curved PAHs; (4) mixed complexes made up by planar and curved PAHs. Our study shows that, in general, calculations employing DFT-D functionals provide more accurate interaction energies than those from M05-2X and M06-2X.