The reduced density matrix dynamics ρ(t) of the molecule-cavity PMET system in this work were propagated at the wavefunction level using the Lindblad mean-field Ehrenfest (L -MFE) ap-proach . MFE is a mixed quantum-classical dynamics method that propagates a quantum subsystem (electrons and photons) alongside a classical subsystem (nuclei) which feel a mean-field force based on the quantum state . MFE has been shown to be accurate for model systems in the non-adiabatic regime (κ ≪ 1) including ET and other charge transfer processes . L -MFE incorporates Lindblad decay dynamics into MFE at the wavefunction level which allows for efficient and accurate simulation of cavity loss even in the presence of coherent laser pumping. The quantum dynamics of the HTC-type subsystem are efficiently propagated using the Chebyshev series expansion approach and taking advantage of the symmetry, which is the key to efficiently solving N molecules coupled to the cavity, where the details of this approach can be found in Ref. 98. The state-independent phonon bath, described by Ĥsb, j , was treated implicitly using a Langevin dynamics approach, which is equivalent to the reduced dynamics of the harmonic ET coordinate under the influence of an Ohmic bath in the Markovian regime . This Langevin description reduces the computational cost of the many-molecule PMET simulation by reducing the number of propagated nuclear DOFs to one per molecule . The computational cost of the simulation was further reduced by manually coding the result of the matrixvector operation of Ĥ acting on the wavefunction (by taking advantage of the symmetry of the HTC type Hamiltonian) in a way that scales linearly with N, see details in Ref. 98. These approaches to reduce the computational cost allowed for N = 1000 molecules to be efficiently simulated on the nanosecond timescale. The number of trajectories was N traj = 10, 000/N such that 10 trajectories were averaged over for the N = 1000 molecule simulations. This small number of trajectories required to reach convergence was possible due to the self-averaging of the population dynamics of the UP and the sum of the acceptor states when multiple molecules are coupled to the cavity. The nuclear time step was dt N = 0.125 fs and the electronic time step was dt E = dt N /4.