In practical terms, the energy decomposition in Eq. ( ) requires three calculations per dimer if the δHF correction is included. One is δE HF,AB in Eq. ( ) while the other two are are XSAPT(KS) with embedding charges and a SAPT(KS) calculation without them. It can be argued that there is some doublecounting of induction effects if the pairwise δE HF,AB corrections are included, as some higher-order induction is partially (though approximately) captured by the self-consistent XPol procedure. In the formalism developed here, the δHF corrections are held apart as a separate term and accuracy benchmarks both with and without this correction are presented in Section 2.1. Note that the δE HF,AB corrections are decoupled from (X)SAPT equations, so there is no difficulty in using different basis sets to evaluate them. Previous work has shown that def2-SVPD affords similar accuracy to def2-QZVPD for the δHF correction, at a small fraction of the cost. Rewriting Eq. ( ) using Eqs. ( ) and (39), we obtain