Surface-hopping simulations were carried out at the OM2/MRCI level, which is a semi-empirical QM method designed for fast excited state calculations . The software package MNDO was used for these calculations. We first ran 10 ps of sampling in the ground state, starting from the optimized structure of the stable form (3D structure C in . Then, samples drawn at random from this initial ground state trajectory were set to the first excited state without any change in nuclear coordinates, if they met standard MNDO criteria such as successful mapping of the active space orbitals, and if they passed a stochastic selection based on the computed excitation probability . About 70% of the initial samples passed and were excited. These excited samples represent an ensemble of Franck-Condon points, and from each we started a simulation replicate. Tully's fewest switches algorithm was used to determine hopping to the ground state. Energies and gradients were evaluated on the fly at the OM2/MRCI level until the fixed simulation length of 4.5ps was reached. A replicate was kept for further use if it had hopped to the ground state and ended the 4.5ps run in the metastable form. The final coordinates of such replicates were used as initial coordinates of classical MD simulations. The other replicates, representing the side processes in were not used to constitute the full rotation trajectory, but offer additional insights, as discussed in the Results and Discussion section.