Performance of Non-Local and Atom-Pairwise Dispersion Corrections to DFT for Structural Parameters of Molecules with Noncovalent Interactions

The nonlocal, electron density dependent dispersion correction of Vydrov and Van Voorhis (Vydrov, O. A.; Van Voorhis, T. <i>J. Chem. Phys.</i> <b>2010</b>, <i>133</i>, 244103), termed VV10 or DFT-NL, has been implemented for structural optimizations of molecules. It is tested in combination with the four (hybrid)­GGA density functionals TPSS, TPSS0, B3LYP, and revPBE38 for <i>inter</i>- and <i>intra</i>molecular noncovalent interactions (NCI) and compared to results from atom-pairwise dispersion corrected DFT-D3. The methods are applied to a wide range of different problems, namely the S22 and S66 test sets, large transition metal complexes, water hexamer clusters, hexahelicene, and four other difficult cases of intramolecular NCI. Critical interatomic distances are computed remarkably accurately by both dispersion corrections compared to theoretical or experimental reference data and inter- and intramolecular interactions are treated on equal footing. The methods can be recommended as reliable and robust tools for geometry optimizations of large systems in which long-range dispersion forces are crucial