Nucleation: the connections between equilibrium and kinetic behavior.

This chapter describes the thermodynamics that govern the formation of nuclei, the least stable species in the reaction path of large, linear aggregates. In the approach described here, parameters are used that have direct molecular interpretations, such as contact energies of the molecular species. The extensive work on sickle hemoglobin is used as a model. An important result is that the nucleus size is expected to vary with initial conditions, such as the initial monomer concentration. Another unexpected result of some generality is that motion of the molecules within the nucleus recovers significant amounts of entropy that would be lost on complete immobilization.