Additionally, the profile indicates an energetic barrier of 10.3 kcal mol -1 going from the G 1 to G 4 wells directly, while the route which should involve the G 2/3 region shows a barrier of 12.6 kcal mol -1 (Figure ). This would seem to indicate that the most appropriate route is a direct transition from G 1 to G 4 , rather than the alternative path via G 3 .