For the coupled Morse potential models, we use the same nuclear Wigner density in Eq. 131 with only one nuclear DOF, and Γ = 1 mω where the mass of the nuclear DOF is set to be m = 20 000 a.u., ω = 0.005 , and the values of R 0 are 2.1, 3.3 and 2.9 for models IA, IB and IC, respectively, and P 0 = 0 for all three models.