with C k denoting the overlap between the initial state and the specific polariton state. In Fig. (a) we show the polariton states that contribute significantly to the dynamics of the three different initial states of interest in the virtual photon case. It is clear that the initial wavepacket with q i = -0.9 au, which exhibits suppression of isomerization, involves different polariton states when compared to the other two initial states. In order to reveal the phase space nature of the participating polariton states we compute the Husimi distribution associated with the various states. The Husimi distribution of the ⟨q⟩ -0.6 -0.4 -0.2 0 ω c , cm -1 500 900 1300 1700 1300 cm -1 1200 cm -1 1000 cm -1 600 cm -1 1600 cm -1 1800 cm -1 FIG. . Left panel shows the T = 1 ps time-averaged quantum reactive coordinate expectation value as a function of the cavity frequency for η = 0.095 and an initial wavepacket eq. 8 with qi = -0.9 au. The panel on the right shows the xc = 0 and pc > 0 phase space surface of sections, as in Fig. (a), for specific cavity frequencies. Note that the average total energies for the various ωc are different.