Heterogeneous Nucleation in the Low Barrier Regime

TL;DR

This study investigates how small impurities influence heterogeneous nucleation in the 2D Ising model, revealing that the free energy barrier remains finite near the stability limit and accurately predicting nucleation times and critical cluster sizes.

Contribution

It provides new insights into the behavior of the nucleation barrier in the low barrier regime and validates theoretical predictions with simulation data.

Findings

The free energy barrier does not vanish near the stability limit.

Predicted nucleation times match direct measurements.

Critical cluster sizes are accurately estimated by the theory.

Abstract

In simulations of the 2D Ising model, we examine heterogeneous nucleation induced by a small impurity consisting of a line of $l$ fixed spins. As $l$ increases, we identify a limit of stability beyond which the metastable phase is not defined. We evaluate the free energy barrier for nucleation of the stable phase, and show that contrary to expectation, the barrier does not vanish on approach to the limit of stability. We also demonstrate that our values for the height of the barrier yield predictions for the nucleation time (from transition state theory) and the size of the critical cluster (from the nucleation theorem) that are in excellent agreement with direct measurements, even near the limit of stability.