Finally, once the torsion parameters have been fit, the parameters are added back into the main FF library. Traditionally, in atom-typed FFs, introducing a new torsion parameter would require the creation of new, potentially redundant atom types. However, since OpenFF uses separate substructure searches for each parameter type (along with a separate parameter hierarchy), the introduction of new torsion parameters does not complicate other parts of the FF, nor does it create issues with conflicting or complex atom types. Instead, the new parameter is simply placed at the bottom of the hierarchy to ensure that it takes precedence when the exact substructure is identified in future parameter assignment workflows.