Effects of surface interactions on heterogeneous ice nucleation for a monatomic water model

TL;DR

This study uses hybrid Monte Carlo simulations to explore how surface properties like attraction and ordering influence heterogeneous ice nucleation mechanisms on various surfaces, revealing the importance of lattice matching and surface-induced ordering.

Contribution

It demonstrates how surface attraction, ordering, and lattice matching affect ice nucleation pathways, providing detailed microscopic insights into heterogeneous nucleation mechanisms.

Findings

Surface attraction and orientational ordering influence nucleation mechanisms.

Lattice matching enhances heterogeneous ice nucleation.

Interfacial free energies vary with surface interaction parameters.

Abstract

Despite its importance in atmospheric science, much remains unknown about the microscopic mechanism of heterogeneous ice nucleation. In this work, we perform hybrid Monte Carlo simulations of the heterogeneous nucleation of ice on a range of generic surfaces, both flat and structured, in order to probe the underlying factors affecting the nucleation process. The structured surfaces we study comprise one basal plane bilayer of ice with varying lattice parameters and interaction strengths. We show that what determines the propensity for nucleation is not just the surface attraction, but also the orientational ordering imposed on liquid water near a surface. In particular, varying the ratio of the surface's attraction and orientational ordering can change the mechanism by which nucleation occurs: ice can nucleate on the structured surface even when the orientational ordering imposed by the surface is weak, as the water molecules that interact strongly with the surface are themselves a good template for further growth. We also show that lattice matching is important for heterogeneous nucleation on the structured surface we study. We rationalise these brute-force simulation results by explicitly calculating the interfacial free energies of ice and liquid water in contact with the nucleating surface and their variation with surface interaction parameters.