The conclusions outlined above are drawn from tests on small dimers where it is possible to use basis sets of quadruple-ζ quality. Tests on two larger systems, namely, a DNA intercalation complex with 157 atoms and the coronene dimer, (C 24 H 12 ) 2 , appear to indicate that def2-TZVPD and jun-cc-pVTZ results are essentially converged. Unlike the results for smaller systems, such as the S22 and S66 dimers where XSAPT + MBD exhibits an accuracy of ∼ 1 kcal/mol with respect to CCSD(T)/CBS benchmarks, in these larger systems the XSAPT + MBD value of |E int | is 2-3 kcal/mol larger (more strongly bound) as compared to the CCSD(T)/ CBS result. The latter benchmark is itself is somewhat more strongly bound than alternative QMC benchmarks. Agreement with the benchmarks improves if the δE HF correction is omitted, for reasons that are unclear but which warrant further study. Given that individual XSAPT + MBD energy components for the S22 dimers are in good agreement with SAPT2+(3)/aug-cc-pVTZ benchmarks, the origin of these discrepancies for larger systems remains an open question.