Potential energy barriers in the kinetic theory of nucleation

Abstract

The problem of partition of the transition free energy δf among the potential barriers for cluster growth (U+i−1) and dissociation (U−i) is discussed. The proposed simple solutions U+i−1=ε+zδfi, U−i=ε−(1−z)δfi, and z= 1/2 [1+sign(δfi)] satisfy all requirements imposed on the problem. Consequently, in the nucleation theory two different critical cluster sizes appear: i*0, which corresponds to the change of sign of δfi and transition in the potentials U+i−1, U−i, and i* (generally different from i*0 ), which accounts for nucleation rate.