Figure (a) provides a comparative analysis of the free energy using a set of beads: One can see that the free energy barrier converged with 4 beads, beyond which the PMF results are nearly not changed. Hence, the free energy barrier is 1.655 ± 0.004 eV, which is slightly lower than the experimental value of 1.665 eV. This difference can be neglected, as the experimental results are also of uncertainties. Next, the thermal rate coefficients k(T) at high-pressure limit were calculated at three temperatures (472.55 K, 503.55 K and 532.95 K). The results are shown in Table . At 472.55 K, 503.55 K and 532.95 K, k(T) is 6.13×10 -5 , 7.16×10 -4 and 7.52×10 -3 s -1 , respectively. The SCTST/VPT2 results reported by Nguyen et al. are included in Table for discussion. At 472.55 K, the RPMD result (6.13×10⁻⁵ s -1 ) underestimates the experimental value (7.5×10⁻⁵ s -1 ) with an error of 18.27%, while SCTST/VPT2 (8.9×10⁻⁵ s -1 ) overestimates the experiment with an error of 18.67%. At 503.55 K, the RPMD result (7.16×10⁻⁴ s -1 ) has an error of 22.6% compared to the experimental value (9.25×10 -4 ), with the SCTST/VPT2 outcome (1.1×10 -03 ) for the error of 18.9%. At 532.95 K, RPMD result (7.52×10⁻³ s -1 ) nearly matches the experimental value (7.67×10⁻³ s -1 ), with a minimal error of 1.96%, whereas SCTST/VPT2 calculation (9.7×10⁻³ s -1 ) overestimates the experimental value by 20.9%. We also calculated the rate coefficients k(T, p) within the fall-off region and offered a direct comparison with Rabinovitch's experimental results and TDME results by Nguyen et al. As shown in Figure , all these results agree well over a wide range of temperatures and pressures, with temperatures ranging from 472.55 K to 532.95 K and pressures spanning from 10⁻² Torr to approximately 10⁴ Torr.