Fig. 5
Coupling and tuning-mode behaviour in DP-Mes. a Representative normal-mode examples of a tuning (left) and a coupling mode (right). The molecular structure was truncated to the core pentacene units for clarity. b Correlation plot of the total time-dependent displacement amplitude of A1 tuning and B1 coupling modes. Contour arrows indicate the direction of evolution and black dots indicate the time of the trajectory. The initial motion is dominated by tuning modes (orange vertical arrows) before a rapid damping of the tuning modes funnels the energy into the coupling modes (green horizontal arrow). c Central pentacene–pentacene bond length and d dihedral angle during the ultrafast singlet fission reaction. Traces are colour coded to match panel (b) and dashed arrows indicate significant increases in the values of the parameters
