Statistical analyses of conformational transitions in small molecular systems

Thermodynamic transitions in nucleation processes of finite systems often
exhibit an interesting first-order-like signature, represented by a convex
region of the microcanonical entropy. This is conveyed to the caloric
temperature which in the transition region possesses a little intuitive
behavior: With increasing energy, the system gets colder. Independently of
the physical interpretation of this "backbending effect", its characteristic
change in monotony not only enables a systematic and quantitative analysis of
the transition. It even allows to reduce the nucleation process to a
hierarchical sequence of subphase transitions. We discuss this in detail for
molecular structure formation processes accompanying protein folding and
polymer aggregation.