Bäckstrom and Norrby predict an energy difference between 4a and 3a of 29 kJ/mol (Figure , with 3a being the lowest, while our methodology predicts an energy difference of 52 kJ/mol. Similarly, the energy difference between 2a-1a and 5a-6a are 16 and 1 kJ/mol, respectively, while our model predicts 27 and 5 kJ/mol. Thus, while our model predicts the correct isomer or mixture in all three cases, it overestimates the energy difference between the two isomers. Note that the difference in the barriers is significantly smaller than the energy difference of the intermediates for the neutral pathways. It is thus difficult to predict mixtures for neutral pathway based on relative energies of intermediates. We use 3 kcal/mol ≈ 12.6 kJ/mol as a cutoff for the accuracy of our computational method, indicating that two isomers are roughly equal in energy according to our theoretical model. But larger energy differences could be computed for cases where mixtures are observed for the neutral pathway.