To put this on a quantitative footing, we performed canonical RI-MP2/(aug-)cc-pVXZ calculations for the S66 data set and then estimated the MP2/CBS limit by combining the Hartree-Fock/(aug-)cc-pVQZ energy with a two-point extrapolation of the correlation energy [Eq. ( )]. For nanoscale van der Waals complexes, our preferred extrapolation scheme would be cc-pV[D/T]Z, for reasons of computational cost, since this procedure requires neither quadruple-ζ calculations nor augmented basis sets. We test this against several other variants, for S66 interaction energies.