Figure 12.

Deviations in improper angles of Sage 2.0.0 optimized geometries with respect to the reference QM structures for the whole benchmark set. The nitrogen centered improper i4 ([*:1]∼[#7X3(*∼[#6X3]):2](∼[*:3])∼[*:4]”) has a wider distribution as it covers both planar and pyramidal instances and can be improved by binning chemistries based on structural differences and splitting the current parameter to apply to subsets with distinct behaviors. This data suggests that, as we expect, there is substantial room to improve improper torsions in subsequent iterations of the force field.