where the sums run over all energies in the specified profiles. Both hydrogen bonded and stacked geometries had less than a 2 kJ/mol MAE from the QM energies, while those with hydrogen bonds performed the best with respect to their relative values (RRMSE). For both types of profiles, reproduction of the QM E ct does not perform as well as E pol , especially for small energies near 10 kJ/mol or less. This is especially true for stacking energies where the charge transfer, as well as polarization energy, is quite small. Nevertheless, the DFT polarization and charge transfer energies agree exceptionally well with AmberFD, especially for H-bonded profiles where these quantities are the largest. Shown in Figure are some examples of this agreement, with both Watson-Crick pairs, wobble G:U, and some noncanonical base pairs (C:C, G:G, and A:C) largely overlapping with the DFT profiles. Recall that the differences between E ct and E pol are fit alongside the combination of the two as well as with the E elec with equal weights. Table shows that the combination of E pol and E ct alone provides a noticeable improvement in RRMSE and minor changes in the MAD over the individual energy components. Adding E elec into the mix provides the best RRMSE improvement, revealing that the parameterization procedure does indeed cancel out remaining errors left over from Step 2. In hindsight, we realize that fitting to simply the difference in the energies rather than to the to a relative quantity such as an RRMSE, may be a cause of this phenomena, as the sum of all three energies will be much larger than the individual components. However, the reasoning behind this choice also has its advantages. First of which, the sum of the energies will be used in simulations as opposed to their relative values, and the overall fit of the sum of all energies will be of most importance here. Second, we stick with a more classical interpretation of polarization within our model.