Here N is the total number of normal modes strained. For states in which this derivative value is positive, increasing strain at the cost of thermal energy will increase reaction kinetics, and vice versa. This can be simplified further, as the value of ∂ϕ n ∂∆Un is ≈ 0 for small to moderate ϕ. We also choose to assess these effects only over a single normal mode, removing the summations and resulting in: