One possible use of ChemPer would be to translate current atom typing force fields into the SMIRNOFF format. To this end, we attempted to generate SMRIKS patterns for the parameters in Amber99SB-ILDN for all fragment types. In this case we have all four valence types -bond, angle, proper torsion, and improper torsion -and the nonbonded types separated into Lennard-Jones and charge parameters. We generated and parameterized our protein with OpenMM, clustered fragments by parameter assigned, and used SMIRKSifier on those clusters. 4.2.1 A polypeptide was created with all possible amino acids. We needed a system with force field parameters which matched with a molecule in a cheminformatics toolkit in order to extract SMIRKS decorators. We started by creating a FASTA file, a text-based format to specify protein sequences, with 20 natural peptides capped at both ends by glycine. Then we used the OpenEye toolkits to parse the file, add hydrogens, and generate 3D coordinates for the polypeptide molecule. An open source tool, oeommtools, was used to convert the OpenEye molecule into an OpenMM system. The polypeptide was parameterized using the internal OpenMM force field file ('amber99sbildn.xml'). We generated clusters of fragments based on their assigned parameters (i.e. bonds were grouped by their equilibrium bond length and force constant). These clusters were then ready to be used with SMIRKSifier to generate SMIRKS patterns for each fragment type. We began by reducing the SMIRKS with 1,000 iterations. This resulted in significantly complex SMIRKS so we continued the reduction for a total of 5,000 iterations. We theorized we would have the most success with either a) or c), since then the more generic SMIRKS would match most of the fragments. Clusters which require more specialized chemistry would then be specified with more decoratorated SMIRKS patterns further down the hierarchy. Success of the SMIRKSifier at maintaining the appropriate clustering varied by fragment type (Figure ). We were able to make SMIRKS patterns which replicated force field parameter assignment for all fragment types. However, there was no ordering technique which was successful for all types of parameters. The Longest SMIRKS option was the best leading to successful SMIRKS patterns for all fragment types except the charge parameters. Charge and angle parameters appear to be the most difficult, given that only one ordering technique was successful. For charges, this may be due to the long distance effects on the parameter. Atoms many bonds away can affect the partial charge assigned to an atom. As discussed below (Section 5) there are still areas for further exploration when it comes to how non-tagged atoms are added to the ClusterGraphs.