Table : Outcomes of surface-hopping molecular dynamics simulation replicates. Columns, from left to right, provide the motor name, the duration of each individual replicate simulation for this motor, the number of simulation replicates, the total number of replicates that failed to isomerize away from the initial stable form, the number of replicates remaining in the excited state, the number that completed photoisomerization and terminated in the metastable form, and the number that completed both photoisomerization and THI and thus terminated in the stable form. (All replicates that completed photoisomerization also hopped from the excited state to the ground state.) In an interesting side-process, a few replicates of Motors S and O actually completed THI (Table ), progressing through the metastable form to the stable form. In all three of these simulations for Motor S, the transition to the stable form is immediately preceded by flipping of the stator pucker to that of the target stable form, as seen in the representative trajectory (video mndo-whole.mp4 in the ESI). The role of the stator pucker in THI is discussed further in Section 3.3. These rapid THI events appear to occur too quickly relative to experimental observations that THI occurs on the microsecond timescale . On one hand, these rapid THI events may be artifacts of the simulation methodology. On the other hand, the computational result could be reconciled with experiment if the kinetics of THI is bimodal, with a fast mode that happens on the picosecond timescale and a slow mode that happens on the microsecond or millisecond timescale. In the fast mode, photoisomerization and THI would happen in quick succession, and the motor would not have time to dissipate much of the kinetic energy from the excited to ground state hop before crossing the THI energy barrier. In the slow mode, however, the motor has time to fully equilibrate, with the kinetic energy from photoisomerization dissipated into many solute and solvent degrees of freedom before THI. If most trajectories dissipate their energy before completing THI, thus following the slow mode, then the fast mode would be a side process which does not contribute much to the overall kinetics observed in experiment. The experimental data available for these motors does not seem to allow one to determine whether THI in fact follows such bimodal kinetics.