A timestep of 0.5 fs was used throughout and the system was kept at 300 K using a Langevin thermostat with a collision frequency of 1 ps -1 . A 50 ps pure MM equilibration was carried out, before switching to QM/MM dynamics for 22 ps. The first 2 ps of the QM/MM trajectory were discarded to allow for additional equilibration upon switching the chromophore Hamiltonian from an MM to a QM representation.