All calculations were performed using Q-Chem v. 6.1.1. For the benchmarks, the integral screening threshold (τ ints ) and the shell-pair drop tolerance (τ shlpr ) were both set to 10 -14 a.u. and the self-consistent field (SCF) convergence criterion was set to τ SCF = 10 -8 E h . The SG-1 quadrature grid 42 was used for B3LYP, the SG-2 grid 43 for ωB97M-V, and the SG-3 grid 43 for M06-2X. The SG-1 grid is used for the nonlocal VV10 correlation in ωB97M-V. These grid choices are the default settings in Q-Chem v. 6.1.1 and were selected in a functional-specific way following careful testing. Figure combines the error statistics for thermochem- istry and barrier heights. (See Fig. for a larger collection of basis sets and Figs. S2-S4 for a breakdown of reaction energies versus barrier heights.) Our assessment includes def2-QZVPD, which should lie near the basisset limit and establishes the inherent accuracy of each functional. Table summarizes the error statistics for selected basis set; see Table for the full set.