This state of affairs implies that the separation of nuclear trajectories implied by Eq. ( ) now has an additional energetic cost associated with the loss of the collective Rabi splitting. The detailed implications of this observation for our present dissociation dynamics model will be considered elsewhere, and here we provide a qualitative argument based on a recent analysis by Cui and Nitzan who have used a simplified truncated basis model to investigate the dynamic consequences of this situation. In that paper it was argued that in contrast to previously discussed polariton decoupling models, the loss of collectivity due to nuclear motion following electronic polariton excitation implies a local distortion of the nuclear potential surface: a local maximum in the nuclear surface associated with excitation of the lower polariton (where energy increases as the collective Rabi splitting is lost) and a local minimum the surface associated with excitation to the upper polariton. In both cases (see a sketch in Fig. ) this implies the emergence of a local barrier that causes a transient slowing down of the nuclear propagation, although for the upper polariton this slowing-down appears to be preceded by a transient acceleration, which may explain the difference between the dynamics of the upper and lower polariton seen in Fig. . Of course, this handwaving argument should not be taken as a basis for quantitative understanding but suggests that transition from collective to individual molecular behavior induced by the nuclear motion following molecular polariton excitation in an optical cavity can have interesting dynamical consequences and may be the reason for the transient slowdown observed in our simulations.