FOKKER-PLANCK EQUATIONS FOR NUCLEATION PROCESSES REVISITED

We present a new approach to analyze homogeneous nucleation based on n on-equilibrium thermodynamics. The starling point is the formulation o f a Gibbs equation for the variations of the entropy of the system, wh ose state is characterized by an internal coordinate or degree of free dom. By applying the method of non-equilibrium thermodynamics we then obtain the entropy production corresponding to a diffusion process in the internal space. The linear laws together with the continuity equat ion lead to a kinetic equation of the Fokker-Planck type, By choosing properly the degree of freedom we are able to obtain a new kinetic equ ation for a global crystallization order parameter (used in recent sim ulations), and also we recover some of the existing equations. The con sistency of the scheme we propose is proved in the quasistationary cas e, Finally, we also outline the way in which our formalism could be ex tended to more general situations. (C) 1998 Elsevier Science B.V. All rights reserved.