In NA-TST, MECPs play a role similar to those of transition states in adiabatic kinetics. We carried out MECP optimizations using the Lagrangian formalism defining the generalized gradient as the gradient on one of the states including the condition of the degeneracy. The description of the algorithm can be found in Ref. 36; additional details are given in SI. To validate the MECP, we analyzed the components of the gradients and the Hessians along the seam and perpendicular to it, using the criteria as in Ref. 40.