The lowest energy connection between the funnels is approximately 120 kJ mol -1 above I and II. Thus, the threshold simulation is able to locate a pathway connecting these two very different crystal structures and the rearrangement in hydrogen bonding required to transform between them results in a high energy barrier. A lower energy connection between I and II might be found if space group symmetry constraints were removed from the Monte Carlo sampling, but it is unlikely that the global structure of the landscape would be changed. The funneled landscape gives an impression that polymorph selection will be strongly influenced by crystallization conditions, which could lead crystal growth into one funnel or the other, and that, once grown, interconversion of the polymorphs is unlikely without a large energetic input. Indeed, both I and II are reported to be stable for months once isolated.