If the IRC did not result in a path connecting the input reactant and product, a constrained optimization on the TS guess, obtained as the maximum energy structure of the interpolated structures, is performed. The bond constraints are set up automatically by considering the difference in adjacency matrices of input reactant and product structure, resulting in a set of bonds being formed/broken during the reaction. only connectivity changes are considered, meaning that, e.g., going from a double bond to a single bond is not considered bond breaking. The length of the set of bonds are fixed to the values in the guess structure from the interpolation, and the remaining structure relaxed. The new TS guess is taken through the same procedure with TS optimization, IRC and check. If the TS is still not found, the entire procedure is repeated but using an electronic temperature of 6000 K in the RMSD-PP reaction path step.