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.

Graphical abstractDownload high-res image (58KB)Download full-size imageHighlights► Several groups of complexes with π⋯π interactions were studied. ► The performance of several DFT functionals was evaluated. ► M05-2X gives rise to a severe underestimation of interaction energies. ► M06-2X only works well for planar complexes with non-eclipsed monomers. ► The best performance corresponds clearly to the DFT-D methods, especially B97-D.