Here we test the performance of the validation procedures described in the Methods section: 1) exactly 1 imaginary frequency of the Hessian, 2) at least one of the active bonds (bonds being broken or formed during the reaction) has an intermediate length, and 3) the eigenvector corresponding to the imaginary frequency has motion along at least one of the active bond stretching modes. The tests are applied to both the correct (83) and incorrect (8) TSs located during run 1. For the incorrect TSs, the first TS found (without constrained optimization) is used in the analysis. The outcome of the individual tests along with the combination of all three tests is shown in Figure (a) for the found transition states of run 1 and in Figure (b) for the failed transition states of run 1.