Nitrogen atoms in conjugated systems make up a large portion of molecules that were optimized to unique structures by SMIRNOFF. While other force fields have likewise had problems with nitrogen planarity, our results display two checkmol descriptors, azo compound and hydrazone, that are especially informative for SMIRNOFF. By visual inspection, molecules with one of these descriptors in between two aromatic rings are especially prominent, as can be seen in boxes 2, 3, and 4 of Figure . QM calculations are necessary to determine if SMIRNOFF's minimized conformers were more or less accurate than other force fields.