Unveiling the face-dependent ice growth kinetics: Insights from molecular dynamics on the basal and prism surfaces
Column-like (a) and plate-like (b) morphologies for ice Ih crystals. If the growth along the basal surface direction is faster than that along the prism1 surface direction, the crystal morphology would be column-like, while it would be plate-like if the reverse is true. The slab models used to study the basal (c) and primary prismatic (d) surfaces of ice Ih in an exemplary MD snapshot with TIP4P/Ice at 260 K. Only oxygen atoms are shown, with those liquid-like indicated by red to highlight the QLL and the remaining represented by blue.
Ice crystals are renowned for their complex fractal geometries branching out from the edges of a hexagonal core at high humidity. Although less intricate, also the compact ice crystals produced at low humidity show an intriguing variability in their shapes which is still not understood. Crystals obtained in these conditions are hexagonal prisms with an aspect ratio that is strongly dependent on temperature: from elongated hexagonal needles to hexagonal platelets. In this paper, through computer simulations, we uncover the molecular growth mechanisms and estimate the growth rates of the relevant ice surfaces , which correlate with the crystal shapes observed at different temperatures.
Understanding and controlling how ice crystals grow is important for a range of fields, including cryobiology, cryopreservation, the aviation industry, atmospheric
and science and the environment. Although many properties of ice and water are well known, others remain elusive, including how the shape of ice crystals develops and which are its determinant factors. This paper provides insights at the molecular level of the link between shape and temperature.
Authors: Jihong Shi; Maxwell Fulford; Matteo Salvalaglio; Carla Molteni