Endo -E ‡ Endo , but not the energy difference between the barrier heights of the two isomers, E ‡ Endo -E ‡ Exo . Thus, Fig. is related to the probability of forming either Endo or Exo species at a given orientation with respect to the cavity field direction. Negative values of this quantity (blue regions) indicate parameter regimes where the endo pathway is lower in energy compared to the exo pathway. Contrary to this, positive values indicate regions where the exo pathway is lower in energy. The cavity polarization angles at Endo -E ‡ Exo . These angles are shown as white circle-dots in Fig. .