Fig. presents the first few vibrational states of the double well model, where |ν L ⟩ denotes the vibrational ground state of the reactant (left well), |ν ′ L ⟩ denotes the vibrationally excited state of the reactant, and similar for the product (right well). The pink arrow represents the thermal activation process from the vibrational ground state, |ν L ⟩, to the vibrationally excited state, |ν ′ L ⟩ in the reactant well. Then, through the coupling between |ν ′ L ⟩ and |ν ′ R ⟩, a chemical reaction occurs. Finally, the vibrational excited state |ν ′ R ⟩ relaxes to the ground state of the product |ν R ⟩. The presence of the cavity mode qc can be viewed as the rate-promoting vibration (RPV) mode, which explicitly enhances the transition rate of |ν L ⟩ → |ν ′ L ⟩. The symmetric double-well model 8 is used to model the reaction, with details in Supporting Information, Sec I. We have used the exact quantum dynamics simulation (HEOM approach) to check that the k/k 0 semiquantitatively converges in the four states subspace.