Organic crystal structure predictions typically leads to a few thousands of local minima on the crystal lattice energy landscape. While this has been developed into a mature and well tracked computational approach, there remain far less theoretical studies on the transition pathways between polymorphs for molecular crystals. This is of drastic contrast to cases of studying reaction pathways or conformational transitions of (bio)molecules in gas or solution phase? For example, the discrete path sampling methods by D. Wales. 

Is any one aware of some good methods to search for transition pathways between molecular crystal polymorphs, particularly, what will be a good choice of coordinates to drive the search algorithm?