Intermolecular forces at ice and water interfaces: premelting, surface freezing and regelation

TL;DR

This paper uses Lifshitz theory and computer simulations to model intermolecular forces at ice-water interfaces, predicting premelting behavior, surface freezing, and regelation phenomena based on van der Waals interactions.

Contribution

It provides a quantitative model linking van der Waals forces to surface free energy and premelting, advancing understanding of ice surface phenomena.

Findings

Incomplete premelting at vapor interface under typical conditions

Complete surface melting occurs above water saturation

Ice regelation can be explained by capillary freezing without bulk melting

Abstract

Using Lifshitz theory we assess the role of van der Waals forces at interfaces of ice and water. The results are combined with measured structural forces from computer simulations to develop a quantitative model of the surface free energy of premelting films. This input is employed within the framework of wetting theory and allows us to predict qualitatively the behavior of quasi-liquid layer thickness as a function of ambient conditions. Our results emphasizes the significance of vapor pressure. The ice vapor interface is shown to exhibit only incomplete premelting, but the situation can shift to a state of complete surface melting above water saturation. The results obtained serve also to assess the role of subsurface freezing at the water-vapor interface, and we show that intermolecular forces favor subsurface ice nucleation only in conditions of water undersaturation. We show ice regelation at ambient pressure may be explained as a process of capillary freezing, without the need to invoke the action of bulk pressure melting. Our results for van der Waals forces are exploited in order to gauge dispersion interactions in empirical point charge models of water.