We compared the energy barriers of two reaction paths: one through the TS reported in ref 18, where the C-C σ bond between the two anthryl groups is temporarily broken, and the other through the TS found in the present study. We attempted to locate the TS from ref 18 but were unsuccessful due to the difficulty in finding an appropriate initial guess. As an alternative, we estimated the energy of this TS using the typical bond dissociation energy of a C-C σ bond, which exceeds 80 kcal/mol. Comparing this estimate with the energy barrier of the TS found in the present study, which is nearly half of the estimated value, we concluded that the reaction path obtained in the present study is likely the primary path. ular distortions (Factor i). Second, forcing linear changes of interatomic distances from reactants to products may also contribute to molecular distortions (Factor ii). To alleviate the redundancy, IDPP reduces the contribution of pairs with long interatomic distances by multiplying each pair potential (eq 3 and Figure ) by r -4 , where r is the interatomic distance. However, this leads to excessive stabilization of long interatomic distances, resulting in the stabilization of undesired bond breakings (Factor iii). Moreover, the r -4 factor causes the potential energy to diverge at r = 0, destabilizing the optimization (Factor iv).