Figure , Panel a, is essential to effectively apply Thom's functions since it displays the absolute value of the Hessian determinant, |det H|. This is shown for the index-one saddles (s1a, s1b, and s1c) and the index-two saddle (s2a). It is worth mentioning that this step is not strictly necessary as the collision between saddles leads to topographical bifurcations rather than catastrophic ones. As the phase portrait is about to change, we can observe that the |det H| at s1c decreases slightly faster than that of the other saddles of index one (s1a and s1b). This is reflective of the impending change. A similar pattern can be seen in the relative distance s1c -s2a, indicating that s1c and s2a are approaching each other at the highest rate. It is also important to note that as the bifurcation is imminent, the separation symmetry between the s2a and the three index-one saddles is lost. This transformation is depicted in Figure After the disappearance of saddles of s2a and s1c, the remaining saddles, s1a and s1b, gradually increase their relative distance, leading to a corresponding increase in their |det H| value. This shift sets the stage for the appearance of a new attractor a2 and another saddle s1d near the original saddles, as depicted in Figure , Panel c. The emergence of this new attractor can be classified as a fold-type catastrophe, indicating that neither s1a nor s1b are degenerate. Within the original BET framework, considering the principles of Thom's work, this observation suggests that there are no signs of an elliptic umbilic yet. As the reaction progresses, on the opposite side of the plane that contains the nitrogen atom and orthogonal to the C3 axis, the coalescence of a1 and s1g forms a wandering point; as seen in Figure , Panels a and b. The subsequent loss of this lone pair is best described through a fold catastrophe, as illustrated in Figure , Panels d and e. Lastly, the emergence of saddles s1h and s2b near the remaining pair (s1e, s1f) marks the final topographic alteration along the IRC. This is shown in Figure , Panel c. Post this merging, the saddles s1h and s2b emerge through a topographical bifurcation, an event that cannot be described in terms of any unfolding (Panel c). Panel d visualizes the variation in the modulus of the Hessian matrix at points a1, s1e, s1f, and s1g as we move along the IRC. The inner plot depicts the asymptotic behavior of |det H| near the bifurcation, and the dashed red line represents the transformation in the phase space. Panel e shows the change in the relative distances a1 -s1e, a1 -s1f, and a1 -s1g as we progress along the IRC. For ease of understanding, various features of the map are color-coded: attractors in purple, saddles of index one in orange, saddles of index two in yellow, and repellors in green. The map does not display gradient lines for simplicity. Additionally, Lewis-like structures are also provided to give a clearer idea of the associated molecular configurations.