Having confirmed consistency in the structural analysis, we next moved to a more quantitative comparison. We found that our ML/MM model overestimates the interaction energies in module. The corresponding MAE for the ML/MM simulations is of 2.4 kcal/mol, while the MM/MM calculations achieve a 1.6 kcal/mol value. It is important to note that since the single-point calculations are performed on the same snapshots, MM/MM simulations here effectively represent an ML/MM approach with mechanical embedding only, suggesting that for this particular ligand, fixed mechanical-embedding charges may suffice. Comparing these results to the non-polarized model (Figure ) shows that the interaction energies are underestimated without polarization. Therefore, some degree of polarization is needed to reproduce the QM/MM reference, but our current model seemingly overestimates its contribution in this case. To explore this further, we performed singlepoints calculations on selected fragments of the FK506 related ligand as ML (or QM) regions. The results (Figure ) indicate that the pipecolyl ring and its bonded -C(=O)-C(=O) and -C(=O)O groups are overpolarized (MAE = 2.9 kcal/mol), whereas the rest of the ligand is accurately modeled (MAE < 0.6 kcal/mol).