Can molecular simulations reliably compare homogeneous and heterogeneous ice nucleation?

TL;DR

This paper investigates how the choice of intermolecular interaction models affects the comparison of homogeneous and heterogeneous ice nucleation, revealing potential overestimations in heterogeneous nucleation enhancement due to modeling differences.

Contribution

It demonstrates that the truncation scheme in water models significantly impacts nucleation temperature comparisons and suggests reevaluating previous heterogeneous nucleation estimates.

Findings

Cut-and-shift Lennard-Jones potential raises ice melting temperature

Modeling differences can lead to overestimating heterogeneous nucleation effects

Analogies between cutoff changes and pressure influence nucleation assessments

Abstract

In principle, the answer to the posed titular question is undoubtedly 'yes.' But in practice, requisite reference data for homogeneous systems have been obtained with a treatment of intermolecular interactions that is different from that typically employed for heterogeneous systems. In this article, we assess the impact of the choice of truncation scheme when comparing water in homogeneous and inhomogeneous environments. Specifically, we use explicit free energy calculations and a simple mean field analysis to demonstrate that using the 'cut-and-shift' version of the Lennard-Jones potential (common to most simple point charge models of water) results in a systematic increase in the melting temperature of ice I$_{\rm h}$. In addition, by drawing an analogy between a change in cutoff and a change in pressure, we use existing literature data for homogeneous ice nucleation at negative pressures to suggest that enhancements due to heterogeneous nucleation may have been overestimated by several orders of magnitude.