• Harmonic angle bending: A subset of 33 out of 40 total parameters were optimized. In case of angles for linear bonds (e.g. triple bonds), only the force constant was optimized, keeping the equilibrium angle constant at 180 • . • Proper torsions: Force constants of 95 torsion parameters out of 167 total parameters were optimized. Some torsion parameters (t165, t166, t167 in Sage 2.0.0) that were used to describe linear bonds were not optimized and they retain the value of zero for their force constants, as all enumerated rotatable bonds must be assigned force constants. • Improper torsions: There were 7 improper torsions, and none were optimized for the 2.0 release. Instead, they were held at the same values as in prior force fields. This was primarily done as these torsions were deemed to be too broadly defined, i.e., covered too diverse a range of chemistries, so will likely need further refinement before we release a force field in which they are refit.