Figure 1.
Energy diagram showing a bifurcation at a ridge-valley inflection, calculated at the M06/aug-cc-pVTZ-PP(SMD)//M06/6-31+G(d,p)/LANL2DZ(Au) level. Relative electronic energies in parentheses, relative free energies in chloroform in brackets, all in kcal/mol at 298 K. For pictures of typical 3D surfaces see Reference 20.