A summary of the energies of stationary points for the methyl torsion and C12-C13 torsion is provided in Table . Briefly, the unrelaxed F-PES and MB-PES do well compared to the unrelaxed DFT benchmark. The unrelaxed MM3 calculated values are shifted substantially (ca. 430 cm -1 ) in energy, based on the DFT GM, but after introducing this shift the MM3 table results predict TS1 in good agreement with the DFT benchmark. However, the predictions for LM, TS2, and the Methyl torsion TS are all considerably low. The optimized F-PES and MB-PES are in good agreement withe relaxed DFT benchmark.