Here x is the reaction energy (units in kcal/mol) and we set min(x) to 100 and max(x) to -100, which was based on empirical experience from the calculations on which ranges of reaction energies to expect. In this way, lower energies map to a higher value between 0-1 compared to higher energies. Molecules with reaction energies outside the normalization range are appropriately assigned to the extremum values of 0 and 1. Molecules with reaction energies less than -100 are assigned to the max score of 1 and molecules with energies higher than 100 were assigned to 0. The normalized energies are then multiplied together and finally scaled with an SA score as shown in equation ( ). The GA optimizing objective is to maximize the number resulting from this equation ( ) and how the SA score is defined is discussed in the following.