The correlation metrics for all methods were relatively poor (Figure ) for this dataset. Only two methods achieved an R 2 or a value over 0.50 (Table ). The statistics suggest there may be some systematic error for a few methods. For example, some methods achieve high correlations along with low accuracy, indicating systematic errors (i.e. the US/GAFF-AM1BCC/TIP3P/HRE-MD/emp_corr method had high correlation with R 2 of 0.74, but RMSE and MAE values that were poor at 4.15 and 3.37 kcal/mol, respectively).