The reaction mechanism at 900 • C is very similar to that of 1000 • C, which also shows a tiny intermediate between the product and transition state, as shown in Figure (b). The free energy barrier value is ∼11.85 kJ/mol, and Figure in the Supplementary Material shows the corresponding evolution of CV1 and CV2. The geometries of the reactant, transition state, and product along the metadynamics trajectory are reported in Figure (b). We have also performed additional metadynamics calculations using different initial conditions to test the reproducibility of these results. In these additional calculations (depicted in Figure in the Supplementary Information), the reactant proceeds to the product through a single transition state with a free energy barrier value of ∼15.73 kJ/mol. The average free energy barrier value obtained from these different initial conditions is 13.79 kJ/mol.