We next use the MBE(2) interaction energies in Table as benchmarks for MBE(2) applied to smaller QM models, using ωB97X-V in basis sets through def2-ma-QZVP. Errors in ∆E int , relative to MBE(2) with R cut = 8 Å, are listed in Table for the best-performing model systems, as determined in Sections 3 .2 and 3 .3. For the small-ligand complexes 181L and 1LI2, the d = 6 Å model tends to exhibit the smallest errors, although the τ 2B = 2.5 × 10 -4 E h model affords errors that are larger by only about 0.5 kcal/mol. For the large-ligand complexes 1O48 and 1BOZ, the τ 2B model is the most accurate one except in one case, namely, 1BOZ at the ωB97X-V/def2-ma-SVP level. Those results are likely to be significantly impacted by BSSE, since 1BOZ is the largest system considered here. In almost every case, fragmentation errors are smaller in the triple-ζ basis set as compared to the double-ζ one, with the 6 Å model of 1BOZ as the lone exception. MBE(2) errors at the ωB97X-V/def2-ma-QZVP level are all ≤ 1.5 kcal/mol for the τ 2B = 2.5 × 10 -4 E h and the d = 6 Å models.