3.4. Data Sets. We will use the S66 data set of noncovalent dimers for high-throughput evaluation of a wide variety of basis sets. This database was developed to sample various types of noncovalent interactions and benchmark interaction energies were reported in Ref. 82 at the level of coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)], extrapolated to the complete basis set (CBS) limit. Per the analysis in Ref. 82, the 66 dimers in this test set are divided into three subsets: hydrogen-bonded dimers, which are characterized by the condition