Rearrangement of Protonated Pinacolyl Alcohol

4 (B3LYP/6-311G ), and 8.0 kcal mol (MP2/6-311G ). No local minimum corresponding to the secondary cation 94 was found on either the B3LYP or the MP2 PES. 

MD were then performed using the HF/6-31G PES. Fifty trajectories were initiated at the reactant position with kinetic energy equivalent to 400 K. These 

The vast majority of the reactive trajectories do not follow the IRC, which is the concerted mechanism. Rather, the reaction proceeds in a stepwise fashion, even though the intermediate is not a local energy minimum. The shape of the PES, and particularly the critical points on this surface, does not control the mechanism. Rather, it is the motion, the dynamics, upon this surface that defines the mechanism. 

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