Is it possible to overheat ice? The activated melting of TIP4P/Ice at solid-vapor coexistence

TL;DR

This study challenges the traditional view that solids cannot be overheated by showing that ice modeled with TIP4P/Ice can remain stable above melting temperature for significant times, impacting how melting points are determined in simulations.

Contribution

It demonstrates that ice can be overheated beyond the melting point in simulations, revealing incomplete surface melting and refining understanding of interfacial thermodynamics.

Findings

Ice basal face remains stable over 100 nanoseconds when overheated by 1 K.

Surface premelting is incomplete in TIP4P/Ice simulations.

Minimum interfacial free energy occurs at a finite premelting film thickness.

Abstract

A widely accepted phenomenological rule states that solids with free surfaces cannot be overheated. In this work we discuss this statement critically under the light of the statistical thermodynamics of interfacial roughening transitions. Our results show that the basal face of ice as described by the TIP4P/Ice model can remain mechanically stable for more than one hundred nanoseconds when overheated by 1 K, and for several hundreds of nanoseconds at smaller overheating despite the presence of a significant quasi-liquid layer at the surface. Such time scales, which are often of little experimental significance, can become a concern for the determination of melting points by computer simulations using the direct coexistence method. In the light of this observation, we reinterpret computer simulations of ice premelting and show that current results for the TIP4P/Ice model all imply a scenario of incomplete surface melting. Using a thermodynamic integration path, we reassess our own estimates for the Laplace pressure difference between water and vapor. These calculations are used to measure the disjoining pressure of premelting liquid films and allow us to confirm a minimum of the interfacial free energy at finite premelting thickness of about one nanometer.