That said, for dimers of charge-neutral complexes there is little reason to push XSAPT to quadruple-ζ basis sets and we find that a good catch-all basis set is def2-TZVPD, although 6-311++G(3df,2pd) also works very well for charge-neutral monomers but exhibits much larger errors for systems containing ions. For ionic systems, where induction effects are very large, best results are obtained using def2-ma-QZVP for anions and def2-QZVPD for cations, although def2-TZVPPD affords results that are only slightly less accurate, with MAEs that are about 0.4 kcal/mol larger.