Fig. presents the population dynamics with Γ = 0, i.e., with no Lindblad decay dynamics. Thus, Eq. 12 reduces to the exact dynamics of a closed system with the Hamiltonian in Eq. 82 (which is a molecule-cavity hybrid system), and Eq. 21 reduces to the Ehrenfest dynamics for the same system. The Ehrenfest dynamics provides nearly identical results compared to the exact dynamics in this case because the nuclei are mostly oscillating on a single adiabatic upper polariton surface (see Fig. ). Because there are no interactions between the |g, 0⟩ state and the other states in the model, the |g, 0⟩ state is not populated.