In general, it can be said that the CP-corrected convergence errors span a smaller range as compared to convergence errors when CP correction is omitted. This discrepancy is especially prevalent in double-ζ basis sets and all Pople basis sets. These observations parallel what has been observed for wave function methods, although the 3.1.4. Timing Data. We have observed that CPcorrected double-ζ calculations often afford interaction energies on par with uncorrected triple-ζ results, so it is interesting to consider which of these methods is less expensive. We assess this using pentane dimer, as it is the largest of the S66 complexes, and Table presents timing data using each of the functionals and basis sets whose convergence statistics are given in Table . In any given basis set, CP correction adds about a factor of 2.5× to the cost of the calculation, which reflects the cost of performing two monomer calculations in the dimer rather than the monomer basis set. This additional overhead pales in comparison to the increased cost of extending the basis set from double-to triple-ζ, however. All three double-ζ calculations in the dimer basis set can typically be performed in 25-50% of the time required for a single triple-ζ calculation of the dimer. If a triple-ζ level of convergence is desired, then CP correction is about 4× less expensive than a single quadruple-ζ calculation on the dimer. An illustration of the trade-off between accuracy and cost is presented in Fig. , using convergence errors for the whole of S66, with BLYP+D3(BJ) and Karlsruhe basis sets. (For other functionals and basis sets, see Figs. S6-S8.) Timing data are shown for pentane dimer. Absent CP correction, double-ζ basis sets afford unacceptably large convergence errors (1.5-2.5 kcal/mol on average), which CP correction reduces below 0.25 kcal/mol, smaller than the intrinsic accuracy of the functional for this data set. All three calculations required for the CP-corrected double-ζ result can be obtained in about 75% of the compute time required for a single triple-ζ calculation, yet basis-set convergence errors and and accuracy with respect to CCSD(T)/CBS are comparable to those obtained using def2-TZVPD. This comparison demonstrates that a CP-corrected double-ζ calculation is a cost-effective strategy to obtain results of triple-ζ quality.