Classical nucleation theory from a dynamical approach to nucleation

TL;DR

This paper derives classical nucleation theory from a dynamical framework based on fluctuating hydrodynamics, introduces a more realistic model with finite interfacial width, and analyzes corrections to nucleation rates and assumptions in CNT.

Contribution

It connects classical nucleation theory to a dynamical approach and develops a more realistic model accounting for finite interfacial width and cluster size effects.

Findings

CNT is recoverable as a limit of the dynamical theory.

Finite interfacial width affects nucleation rate corrections.

Breakdown of monomer attachment/detachment picture at high supersaturation.

Abstract

It is shown that diffusion-limited classical nucleation theory (CNT) can be recovered as a simple limit of the recently proposed dynamical theory of nucleation based on fluctuating hydrodynamics (Lutsko, JCP 136, 034509 (2012)). The same framework is also used to construct a more realistic theory in which clusters have finite interfacial width. When applied to the dilute solution/dense solution transition in globular proteins, it is found that the extension gives corrections to the the nucleation rate even for the case of small supersaturations due to changes in the monomer distribution function and to the excess free energy. It is also found that the monomer attachement/detachment picture breaks down at high supersaturations corresponding to clusters smaller than about 100 molecules. The results also confirm the usual assumption that most important corrections to CNT can be acheived by means of improved estimates of the free energy barrier. The theory also illustrates two topics that have received considerable attention in the recent literature on nucleation: the importance sub-dominant corrections to the capillary model for the free energy and of the correct choice of the reaction coordinate.