Free energy surface of two-step nucleation

TL;DR

This study validates Iwamatsu's theoretical free energy surface for two-step nucleation by comparing it with Monte Carlo simulation results, showing excellent qualitative and quantitative agreement across various conditions.

Contribution

The paper provides the first direct, parameter-free comparison of Iwamatsu's theoretical FES with simulation data for TSN, confirming its predictive accuracy.

Findings

The theoretical FES accurately predicts simulation results across different regimes.

Qualitative features of the FES are well captured by the theory.

Quantitative agreement between theory and simulation is very good.

Abstract

We test the theoretical free energy surface (FES) for two-step nucleation (TSN) proposed by Iwamatsu [J. Chem. Phys. 134, 164508 (2011)] by comparing the predictions of the theory to numerical results for the FES recently reported from Monte Carlo simulations of TSN in a simple lattice system [James, et al., J. Chem. Phys. 150, 074501 (2019)]. No adjustable parameters are used to make this comparison. That is, all the parameters of the theory are evaluated directly for the model system, yielding a predicted FES which we then compare to the FES obtained from simulations. We find that the theoretical FES successfully predicts the numerically-evaluated FES over a range of thermodynamic conditions that spans distinct regimes of behavior associated with TSN. All the qualitative features of the FES are captured by the theory and the quantitative comparison is also very good. Our results demonstrate that Iwamatsu's extension of classical nucleation theory provides an excellent framework for understanding the thermodynamics of TSN.