Correlation plots for the F-PES vs B3LYP and MB-PES vs B3LYP training energies are given in Figure SI-3 over the range 0 cm -1 to 80 000 cm -1 . As usual, the precision deteriorates for energies at the high end of this range. A corresponding correlation plot for the F-PES gradients (which were not used in training) is given in SI, Figure .