Here, |α⟩ ∈ {|g⟩, |e⟩} represents the electronic ground or excited state, which are treated as diabatic states in this model, R represents the reaction coordinate, and TR = P 2 /2M is the nuclear kinetic energy operator associated with R, with nuclear mass M = 550 Da. The detailed expression of E α (R) is provided in Appendix C. The second term in Eq. 77 is the Hamiltonian of the quantized photon mode inside the cavity with the frequency ω c , and â † and â are the photon creation and annihilation operators, respectively. The third term in Eq. 77 describes the molecule-photon coupling through electric-dipole interactions under the dipole gauge, where σ † = |e⟩⟨g| and σ = |g⟩⟨e| are the molecular excitonic creation and annihilation operators, respectively, and the light-matter interaction strength ℏg c is treated as a parameter in this model. The dipole self-energy