CTY's integrated activation energy estimation for reactions is a computationally inexpensive way of prioritizing TSs for optimization, e.g. with the Nudged-Elastic-Band method, when computation time is restricted. However, this study also showed the limitations of this estimation approach: most activation energies for barrierless dissociations are underestimated due to the position of the DS, which separates the reactant and product regions, being generally situated at lower potential than the dissociation limit. In this study, the estimates for TS barriers are on average only 8.6 kcal mol -1 below the actual (ReaxFF/CHO2016) value whereas the estimates for barrierless reactions are on average 38.5 kcal mol -1 below the actual value. Consequently, this estimation is susceptible to underestimating such types of barriers, i.e. of reactions that only break bonds, thus the estimates for barrierless dissociations typically represent a lower bound.