A detailed illustration of the crossover procedure in the GA is shown in Figure . There are several random selection steps in the procedure, and unless otherwise specified a random selection has equal probability for each option. The first step of the crossover procedure is to select the catalyst and ligand we want to operate on. To do this, we first select Cat 1 or Cat 2 and then we select either the anionic (L 1 ) or the neutral (L 2 ) ligand in this catalyst. Then we can do one of two types of crossover on the chosen ligand. There is a 20% probability of simply performing a switch of the selected ligand with the ligand of the same type in the other catalyst. There is a 80% probability of performing ligand crossover between the selected ligand and the ligand of the same type in the other catalyst. The bottom of figure shows an example in both cases where Cat 1 has been selected together with the anionic ligand L 1 .