Transition dynamics and metastable states during premelting and freezing of ice surfaces

TL;DR

This study uses large-scale molecular dynamics simulations to explore the transition dynamics, metastable states, and surface inhomogeneities involved in the premelting and freezing processes of ice surfaces.

Contribution

It reveals the roles of supercooling, superheating, and surface inhomogeneity in ice phase transitions, highlighting the importance of metastable states and system size.

Findings

Supercooling and superheating states are involved in phase transitions.

Surface inhomogeneity accelerates premelting but not freezing.

Freezing can be hindered by stacking order mismatch.

Abstract

The premelting of ice is well known, but little is known about how the premelted and solid surfaces convert to each other. In this work, the transition dynamics between two phases are revealed with large-scale molecular dynamics simulations. Supercooling and superheating states exist in the transition, and are overcome by nucleation-like processes. The natural inhomogeneity of ice surfaces enhances nuclei formation, while it only accelerates premelting but not freezing. Furthermore, the complete freezing of ice surfaces may be hindered by the stacking order mismatch between nuclei. This work points out the importance of metastable states in premelting, and the necessity of a large system scale in describing its transition process.