The best accuracy is obtained for SAPT0 + δHF/jun-cc-pVDZ, using a basis set that removes certain diffuse functions from aug-cc-pVDZ. That basis, which is called aug-cc-pVDZ ′ in some older literature, has been previously recommended for SAPT0. However, the limited basis set amounts to a form of error cancellation, which works better in small dimers than it does in complexes with larger monomers. For large-molecule vdW complexes, SAPT0 and other MP2-like methods fail badly. Terms beyond second order are required to obtain benchmark-quality interaction energies from the SAPT formalism. To this end, methods known as SAPT2+(3) and SAPT2+3 have been developed, which include a subset of the possible third-order terms. For small molecules, SAPT2+(3) + δHF achieves subkcal/mol accuracy with respect to CCSD(T), but both SAPT2+(3) and SAPT2+3 exhibit the same O(N 7 ) scaling as CCSD(T). As such, these methods are prohibitively expensive for molecules with more than 10-20 non-hydrogen atoms. For larger systems, DFT-based EDAs have long been the only means available to analyze intermolecular interactions. The XSAPT family of methods was developed as a way around that bottleneck.