ometry optimizations and a total of 21208 / 21658 gradient evaluations, depending on the ordering of dimensions. The TorsionDrive calculation ran for 33 wavefront propagation steps, involving a total of 4953 energy minimizations and 166714 gradient evaluations. The number of gradient evaluations in the TorsionDrive calculation is about 7.5 times greater than the sequential relaxed scans, but the wall time may be greatly reduced if parallel resources are available as each wavefront propagation step could launch up to 300 energy minimizations in parallel. In the ideal case of that all calculations are able to run in parallel, the TorsionDrive calculation walltime would be equivalent to around 33 sequential geometry optimizations, i.e. ≈ 17 times faster than the sequential relaxed scans. The wavefront propagation procedure of TorsionDrive is naturally able to incorporate multiple starting conformations. The initial constrained optimizations are performed on all starting structures with the torsion angle constrained to the closest grid point. If more than one initial structure is mapped to the same grid point, the lowest energy optimized conformer is used to launch new constrained optimization for neighboring points. This feature is beneficial because a grid of torsion angles can be covered in a smaller number of wavefront propagation steps when starting from multiple structures, and it also provides a natural way to consistently include the lowest-energy local minimum from multiple initial guesses.