where, the relative conformer energies were calculated with respect to the QM minimum energy conformer (labeled 0 𝑡ℎ ) within each molecule, through a conformer matching process. We exclude the minimum energy conformer, which has a ΔΔ𝐸 of 0.0, in calculating ΔΔ𝐸 statistics so that final results were not skewed towards zero. Improvements over generations of force fields can be seen in the step plots in Figure , where the population density in the bins closer to minimal error are increasing for RMSD and TFD metrics. In the case of ΔΔ𝐸 the histogram stays close to the best among earlier generations, Parsley 1.2.0. The slight degradation observed here could be due to the reduced number of optimized geometry targets used in training the force field; this reduction means that the overall fit places slightly less weight on energetic agreement relative to geometric agreement. In particular, there is a reduction of around 1082 optimized conformers between Parsley 1.2.0 and Sage 2.0.0 training sets, and a comparable performance is achieved with a reduced set of targets.