Mechanism of anisotropic surface self-diffusivity at the prismatic ice-vapor interface

Ivan Gladich, Amrei Oswald, Natalie Bowens, Sam Naatz, Penny Rowe, Martina Roeselova, Steven Neshyba

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Abstract

Predictive theoretical models for mesoscopic roughening of ice require improved understanding of attachment kinetics occurring at the ice-vapor interface. Here, we use classical molecular dynamics to explore the generality and mechanics of a transition from anisotropic to isotropic self-diffusivity on exposed prismatic surfaces. We find that self-diffusion parallel to the crystallographic a-axis is favored over the c-axis at sub-melt temperatures below about -35 °C, for three different representations of the water-water intermolecular potential. In the low-temperature anisotropic regime, diffusion results from interstitial admolecules encountering entropically distinct barriers to diffusion in the two in-plane directions. At higher temperatures, isotropic self-diffusion occurring deeper within the quasi-liquid layer becomes the dominant mechanism, owing to its larger energy of activation.

Original languageEnglish
Pages (from-to)22947-22958
Number of pages12
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number35
DOIs
Publication statusPublished - 7 Aug 2015

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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