Optimization and frequency calculations were performed producing a second, generally similar, energy curve (eqs A7 to A10 in table 2) and to nearly identical configuration geometries, based on RMSD of 0.020A-0.028A; here, the RMSD was determined by Kabsch algorithm . Equation (A9) in table 2 was the most sensitive to this reassignment and change in basis, but exhibiting a free energy difference of only 3.1 kJ/mol.