Compared with the Lennard-Jones potential (Eq. 1) - , the derivation of Eq. 19 is straightforward and concise without adopting any fictional assumptions, such as the electron repulsion or the dispersion force . Moreover, Eq. 19 indicates that Le decreases as the temperature increases. This is consistent with the anticipation that the faster the particles, the closer the accessible distance, which is vital to the chemical reaction.