Classical nucleation theory predicts the shape of the nucleus in homogeneous solidification

TL;DR

This paper develops a continuum framework from atomistic simulations to predict the shape and interfacial energy anisotropy of nuclei in homogeneous solidification, confirming classical models' accuracy.

Contribution

It introduces a method to derive atomistic insights into nucleus shape and interfacial anisotropy using a reverse Wulff construction from simulations.

Findings

Nucleus shape is nearly spherical.

Interfacial energy anisotropy aligns with classical models.

Framework successfully links atomistic simulations to continuum predictions.

Abstract

Macroscopic models of nucleation provide powerful tools for understanding activated phase transition processes. These models do not provide atomistic insights and can thus sometime lack material-specific descriptions. Here we provide a comprehensive framework for constructing a continuum picture from an atomistic simulation of homogeneous nucleation. We use this framework to determine the shape of the equilibrium solid nucleus that forms inside bulk liquid for a Lennard-Jones potential. From this shape, we then extract the anisotropy of the solid-liquid interfacial free energy, by performing a reverse Wulff construction in the space of spherical harmonic expansions. We find that the shape of the nucleus is nearly spherical and that its anisotropy can be perfectly described using classical models.