The last step of the procedure is the DFT-refinement (ωB97X-D/def2-TZVP) of the reactions found at the semiempirical level of theory that have reaction energies and barriers below 40 kcal/mol. Again, our validation procedure is as described in and except that we only test one of the five possible TS guess structures that can be extracted from the five RMSD-PP runs in order to reduce the computational cost of the DFT part of the procedure. The barriers and reaction energies at DFT level of theory are computed as stated in , adding zero-point vibrational energies to the electronic energies of reactant, product and transition states (TSs) before calculating the barrier as the energy difference between TS and reactant and reaction energy as the energy difference between product and reactant.