Irreducible finite-size effects in surface free energies from crystal-nucleation data

TL;DR

This study reveals significant finite-size effects in surface free energy estimates from nucleation data, showing that experimental and simulation values can differ substantially due to size-dependent effects, necessitating revisions of previous estimates.

Contribution

The paper demonstrates that finite-size effects cause large discrepancies in surface free energy estimates from nucleation data, which cannot be corrected by simple thermodynamic methods.

Findings

Simulation and experimental estimates differ by over 100%.

Finite-size effects significantly impact surface free energy measurements.

Most published nucleation-based surface free energies may need revision.

Abstract

In this Letter we report a simulation study in which we compare the solid-liquid interfacial free energy of NaCl at coexistence, with the value that follows from the height of the homogeneous nucleation barrier. We find that the two estimates differ by more than 100%. Similar, although smaller discrepancies are found for crystals of hard-sphere colloids and of Lennard-Jones ("argon") particles. We consider a variety of possible causes for this discrepancy and are forced to conclude that it is due to a finite-size effect that cannot be corrected for by any simple thermodynamic procedure. Importantly, we find that the surface free energies that follow from real nucleation experiments should be subject to large finite size effects. Taking this in to account, we obtain quantitative agreement between the simulation data and the surface free energy of NaCl that follows from nucleation experiments. Our finding suggests that most published solid-liquid surface free energies derived from nucleation experiments will have to be revised.