Table 4. Regularization Scales Used in Optimizing Force Field Parameters with ForceBalancea.
| parameter | regularization scale σp |
|---|---|
| bond force constant Kr | 100 kcal/(mol/Å2) |
| bond equilibrium length r0 | 0.1 Å |
| angle force constant Kθ | 100 (kcal/mol)·rad2 |
| equilibrium angle θ0 | 20° |
| proper torsion barrier height K | 1 kcal/mol |
| vdW well depth ϵ | 0.1 kcal/mol |
| vdW minimum Rmin/2 | 1 Å |
a
Regularization helps when we are training on smaller data sets, as the final optimized parameter values apply generally to a wider chemical space. The values were chosen based on chemical intuition and also by looking at the distribution of parameter values in SMIRNOFF99Frosst.