Figure : Weighted root-mean-square-error (wRMSE) in kcal mol -1 for the test set data for each of the functionals optimized in this paper. This includes the range-separated hybrid (RSH) ωB97X21-D3(BJ), the double hybrid (DH) ωB97X-MP2-D3(BJ), and the UW12 hybrid WM21-D3(BJ). Both ωB97X21-D3(BJ), and WM21-D3(BJ) refer to the final selfconsistent versions of the functionals, while ωB97X-MP2-D3(BJ) is calculated using ωB97X orbitals. For comparison, the results for the initial fitted version of ωB97X21-D3(BJ) and WM21-D3(BJ) calculated using the ωB97X orbitals are also included. These are given the suffix '-0' to differentiate them from the final functionals.