Polymers cannot be easily represented as the repeating, statistical entities that they actually are. While this is an active area of research, we simply encoded the structure of the monomer. Additionally, regioregularitywhich is a factor for both polymers and NFAsis not easily represented in SMILES notation. For example, IT-F and other NFAs with mono-substituted end groups are usually obtained as a mixture of three isomers, the populations of which play a role in determining PCE. However, SMILES forces us to choose a single isomer.