We augmented the list of atom-types by adding some and removing some others (such as those defined for fixed biomolecules such as DNA or protein). New ones were created by borrowing parameters from the closest existing types. These additions were made in cases where there was a large variety in the allowed substituents, which could be expected to cause deviations in the partial charges of the central atom based on the substituent chosen. In this case, a minimal molecule with the atom-type in question was constructed and optimized using Gaussian 09 to compute charges. The complete details for this method are given in section II C. The program uses the force field data provided in GROMACS 2018 . We had a total of 166 atom-types. However, many of these atom-types are still too specific and often not used during molecule generation.