From Table , it may seem that PIM and N-POL MD are more accurate than AIMD in predicting formation constants. However, we do not draw such conclusions here because formation constants are derived from the corresponding reaction FES. As discussed above, FES from N-POL MD are unable to predict the relative stabilities of the different metastable states correctly. We do not have any data to prove that FES from PIM are more accurate than their AIMD counterparts.