The eight-water case demonstrates the matching of PCMs with different hydrogen bonding families. Analogous 8H2O configurations were created by stacking identical rings from the optimized 4H2O models and then optimizing; this was done to reduce optimization effort. These resulted in three starting parent configurations of 8H2O. One stage of analysis was performed for each of the parent configurations and are shown in Figure . The input configuration would be referred to as the "parent" and the generated configurations would be referred to as "child proto-PCMs." In Figure , each of the parent PCMs produced six child proto-PCMs and all except two of the child proto-PCMs optimized to PCMs that fall under the same hydrogen bonding family as their parent PCMs. In other words, nineteen PCMs were found. The PCM family memberships were verified by checking the configurations against the respective ledgers of the parents. Three distinct families emerge. The differences in energies are illustrated in Figure . Note that hydrogen bonding "family a" is 18 kJ/mol lower than "family b." This is expected since "family a" was made from 2 four-water NSNS configurations stacked together, which had relatively lower energies, while "family b" was made from 2 four-water NNNS configurations, which had higher energies.