With the thermal contributions evaluated, we will examine the electronic binding energies predicted for different single-point energy methods on our ωB97X-D3BJ/aug-cc-pVTZ-PP structure. This can be seen for DFT-based methods in Figure and for coupled-clusterbased methods in Figure . The reference value chosen for this was ZORA-CCSD(T)/TZVPP because it was the highest level of theory for which the binding energies could be calculated for all the dimer structures. DKH-CCSD(T)/TZVPP could be carried out for the majority of the dimers, however, it proved too expensive for the largest iodine oxide dimers: IT-IP and IP-IP. In Figure , it can be observed that none of the DFT methods, even those with triple ζ basis sets, predict the binding energy well, with significant mean errors of several kcal/mol for all of them. When downgrading to a double ζ basis set it can be observed that the energies are shifted towards under-binding, which leads to a more negative error.