First, classical MD simulations were appended to the QM surface-hopping MD trajectories (Section 2.1) to construct full rotation trajectories of Motor S and Motor N. This was not done for Motor O, for reasons detailed in Section 2.3.) The initial structure of each classical simulation was set as the final structure of one of the QM surface-hopping trajectories in the metastable form (Section 2.1). One motor molecule was solvated with 600 molecules of dichloromethane in a 40 Å cubic periodic box, using the software Packmol . After energy minimization, the solute was restrained in position while the system at constant volume was heated to 300K with the Berendsen thermostat. It was then equilibrated, with restraints still on, at 300 K and a pressure of 1 bar with the Langevin thermostat and the Monte Carlo barostat, mimicking the experimental conditions for microsecond THI . Finally, restraints were removed for 1 µs production runs at the same temperature and pressure. In classical MD, the Langevin collision frequency we mainly use was 1/ps, but different values were also used to evaluate the effect of this parameter on the kinetics (discussed later in Section 3.3.4). The trajectories that completed THI were concatenated with their corresponding surface-hopping MD trajectories to give continuous trajectories of the full 180 • motor rotation.