Figure 8.

(a) Interaction energies of the water hexamer isomers calculated with the SCME/GAP, WHBB, and MP-pol many-body potential energy functions using the MP2 optimized geometries of ref (218). Also shown as a reference are the corresponding values obtained at the CCSD(T)-F12/VTZ-F12 level of theory in the complete basis set limit.²¹⁷ (b) Same comparison as in (a) using seven popular DFT models. (c) Same comparison as in (a) using the same seven DFT models as in (b) with the D3 pairwise additive dispersion correction of ref (257).