where |Ψ a (R)⟩ is referred to as the a th polariton state and E a (R) is the a th polariton surface or cavity Born-Oppenheimer surface. Note that both |Ψ a (R)⟩ and E a (R) parametrically depend on R, analogous to Eq.21 for the adiabatic states and energies of the bare molecule.