Nevertheless, the second-best non-double-hybrid functional is r 2 SCAN-D4, the second revision of Sun, Ruzsinszky, and Perdew's fully constrained meta-GGA functional, and other pure meta-GGA functionals-M06-L and B97M-D4-performed about as well as common hybrid functionals like M06-2X, B3LYP, and PBE0. At least on Wiggle150, the exact choice of density functional appears to matter more than the precise rung of Jacob's Ladder, and pure functionals can give good performance where hybrid DFT is impossible or impractically slow. These results also support the emerging conclusion that r2SCAN should replace PBE where possible for periodic thermochemistry. Methods color coded based on position along "Jacob's Ladder." Methods using smaller basis sets fared substantially worse on this benchmark set. While full evaluation of basis-set effects on Wiggle150 is outside the scope of this work, we scored two popular double-ζ DFT methods, B3LYP-D3BJ/6-31G(d) and wB97X/6-31G(d), and found that these methods gave markedly worse performance than their quadruple-ζ congeners. We attribute this to the high variation in bond length, which likely introduces a small amount of bond breaking into the benchmark; double-ζ basis sets are known to be inaccurate for thermochemistry, ( 36 ) so their poor performance here is unsurprising. Similarly, the r 2 SCAN-3c composite method was markedly worse than its non-composite counterpart. This contrasts with results on GMTKN55, where r 2 SCAN-3c outperforms r 2 SCAN-D4/def2-QZVP on relative conformer energies. ( )