Cumulative reaction probability N(E) as estimated from empirical bimolecular rate constant k(T)

Approximate cumulative reaction probabilities have been calculated from two empirical rate equations: one is the 3-parameter rate equation, ATnexp(−E/kBT), and the other is the modified Arrhenius equation, A′exp(−E0/kBT2+T02) proposed in Chem. Phys. Lett. 160 (1989) 295, for expressing the rate constants at low temperatures. Numerical calculations were made for the D + H2 → DH + H reaction. It is shown that this reaction occurs mainly through tunneling at 200 K, and that the 3-parameter rate equation involves the tunneling effect along with the correction at high temperatures.