Next, with the goal of evaluating the ability of QUBE to recreate intramolecular energetics including torsional rotations, separate liquid simulations of 3-HA, captan and bromacil solvated in boxes containing 1000 TIP4P water molecules were performed. We then extracted 500 conformations from each simulation and computed the relative single point energies of each snapshot of the molecule using OPLS, QUBE and QM (with the same DFT functional and basis sets as used for the parameter derivation). Figure shows the correlation between the relative MM and QM energies for each of the three molecules. We note in making this comparison that, unlike QUBE, the OPLS FF was not parametrized against this QM model chemistry. Compared to OPLS, the correlation between MM and QM energetics is improved, and significantly QUBE does not sample any configurations that are lower in energy than the optimized QM structures. Figure shows in more detail the fitting of QUBE torsion parameters to QM potential energy scans, as well as the dihedral angles sampled during MM dynamics in water. Encouragingly, despite the simple MM functional form used, and the fact that it is optimized for reproducing condensed phase properties, QUBE is not only able to reproduce the minimum energy structures, but also sample physically reasonable structures in liquid simulations, which is encouraging for future use in computer-aided drug design. Finally, the free energies of hydration of captan and bromacil were calculated using the same protocol described earlier, and the results are shown in Table alongside the experimental data and those computed using a GAFF parametrization. The errors of around 4 kcal/mol in the QUBE FF are higher than those reported for the small molecule benchmark set, but consistent with expected cumulative errors in hydration free energy prediction. Nevertheless, improvements in accuracy are required, particularly for hydration free energy calculations, if QUBE is to be used in predictive computer-aided drug design.