The origin of the observed dispersion could be noise introduced due the comparison of different levels of theory, since the atomic charges for the ME approach are derived from ωB97x/def2-TZVPP while the EE reference corresponds to PBE/DZVP calculations. To further evaluate this possibility, we repeated the calculation of the E ME+P ML/MM energy for a randomly selected subset of structures using PBE/DZVP derived MBIS charges (Figure ). No significant differences were observed in this test when changing the functional and the basis set, allowing us to discard the level of theory as significant source of dispersion in the correlations of Figure . Alternatively, we hypothesize that such noise could be related with atom type polarizabilies not being able to capture specific atomic environments, or with intrinsic limitations of the ME approach given by the partitioning of the electron density.