Interface limited growth of heterogeneously nucleated ice in supercooled water

TL;DR

This study uses molecular dynamics simulations to reveal how surface roughness and interfacial water dynamics limit the maximum growth rate of heterogeneously nucleated ice in supercooled water, highlighting atomistic mechanisms affecting ice formation.

Contribution

It provides new atomistic insights into how surface roughening and interfacial water behavior control ice growth rates in supercooled water.

Findings

Surface roughening limits ice growth at large undercoolings.

Concave surface regions promote direct freezing of interfacial water.

Attachment kinetics peak when interfacial water converts efficiently to ice.

Abstract

Heterogeneous ice growth exhibits a maximum in freezing rate arising from the competition between kinetics and the thermodynamic driving force between the solid and liquid states. Here, we use molecular dynamics simulations to elucidate the atomistic details of this competition, focusing on water properties in the interfacial region along the secondary prismatic direction. The crystal growth velocity is maximized when the efficiency of converting interfacial water molecules to ice, collectively known as the attachment kinetics, is greatest. We find water molecules that contact the intermediate ice layer in concave regions along the atomistically roughened surface are more likely to freeze directly. The increased roughening of the solid surface at large undercoolings consequently plays an important limiting role on the rate of ice growth, as water molecules are unable to integrate into increasingly deeper surface pockets. These results provide insights into the molecular mechanisms for self-assembly of solid phases that are important in many biological and atmospheric processes.