A series of tests were performed to evaluate success for each tool described above -the original SMARTY sampler (SMARTY ), the elemental SMARTY sampler (SMARTY ), and SMIRKY -in discovering chemical perception of the complexity in existing force fields. Each test was run on each of the three molecule sets described above, AlkEthOH, PhEthOH, and MiniDrugBank. For SMARTY , tests were performed for each element with more than one atom type in the molecule set. Using the elemental sampler on elements with only a single atom type (such as halogens) would not provide useful insight since even a generic SMARTS pattern could match the relevant chemical perception. SMIRKY tests were performed for bond, angle, proper torsions, and nonbonded (vdW) fragment types. While the SMIRNOFF format and SMIRKY support improper torsions, there are a very limited number in smirnoff99Frosst so those were not tested.