Suppose the system is in thermal equilibrium and one element in the reactant system performs an adiabatic transition from the state 𝑞 to the product system. At this point in time, the number of elements in the other states are unchanged and ∆𝑛(𝑞 + 1) = ∆𝑛(𝑞 -1) = 0. Under the condition, that ∆𝜀 << 𝓀 𝐵 𝑇 so that 𝑒 -∆𝜀 𝓀 𝐵 𝑇 ≈ 1, Eq. 6a simplifies to Eq. 7, called now the thermal rate. 𝑑 𝑛(𝑞)