SAF v4.0 presents a minimal classical framework that unifies thermal, solvent, and photochemical reactivity through a single equation: E■,final = E■,base − (1240/λ) The photon term (1240/λ, eV) is derived from the Planck–Einstein relation and is introduced as a direct correction to the activation energy. The model treats photochemical activation as a reduction in the effective barrier rather than a separate mechanistic class. The framework is implemented in a compact Python codebase (~70 lines) and requires only basic inputs: temperature, dielectric constant, and wavelength. Validation across representative reactions (thermal, solvent-mediated, and photochemical) shows qualitative agreement with known experimental behavior. This approach provides a computationally inexpensive method for rapid reaction feasibility screening and offers a unified energetic perspective on reactivity
Arun Singh Pundir (Fri,) studied this question.