In addition to the gaussian modifier suggested by Gao and Coley , we apply an extra gaussian modifier on the average of the SA score for the ligands in a catalyst. The form of this gaussian is visualized in figure S7. This modifier maps the upper range of values for the SA score into a smaller range on the y-axis. In this way, molecules in the upper range of average SA scores would need less improvement in reaction energy scores in order to survive throughout populations allowing for more evolutionary flexibility. Equation (S1) shows the form of the Gao and Coley modifier and equation (S2) shows our extra modifier. Equation (S3) shows the final equation we use to obtain the final SA score.