As compared to electrostatics or dispersion, the exchange and induction energies are more sensitive to the choice of basis set and these are not converged unless triple-ζ basis sets are used. Dunning's correlationconsistent basis sets can certainly be used for this purpose, but insofar as hybrid XSAPT methods have not been designed with the intention to extrapolate to the complete-basis limit, the Dunning basis sets are more expensive than other alternatives that afford similar accuracy. Karlsruhe "def2" basis sets work well in this capacity, although we find that Pople basis sets with additional polarization functions, such as 6-311+G(3df,2pd), can also provide high-quality results, comparable to def2-TZVPD in many cases. The use of Pople basis sets is sometimes maligned in modern electronic structure theory but they are very efficient in certain quantum chemistry codes that can take advantage of sp shells. As applied to Cl -(H 2 O) 28 , for example (with Cl -as one monomer and the water cluster as the other), XSAPT calculations with 6-311+G(3df,2pd) afford a 2× speedup over def2-TZVPD despite the fact that the Pople basis set has 253 more functions! The 6-311+G(2df,2p) basis set affords a 5× speedup over def2-TZVPD, and both of these Pople basis sets afford interaction energies within 0.5 kcal/mol of the def2-TZVPD value.