Fig. 4. Schematic diagram showing calculations of Gibbs free energies on the proposed “photo-to-thermal pathway” using the TST method. All the symbol used are explained in the kinetics and thermodynamics of photoisomerization subsection. (I)^* → (II)^*,§ = relaxation of the S₀ → S₁ vertically excited structure (I)^* to structure (II)^*,§ at the S₀/S₁ intersection; (II)^§ → (III) ⇌ (IV)^‡ → (V) = relaxation of structure (II)^§ at the S₀/S₁ intersection to the equilibrium structure (V) in the S₀ state.