Molecular Dynamics Study of the Correlation Between Local Diffusivity of Water Molecules and Ice Nucleation in the Vicinity of a Nanostructured Surface

Abstract

The influence of solid surface properties on ice nucleation are well-known and the influence of the dynamical heterogeneity (DH) of water molecules on ice nucleation has also attracted attention recently. Dynamical heterogeneity refers to water molecules in supercooled water that have regions of high mobility as well as those of low mobility. In the present study, we investigated the effect of the dynamic properties of water molecules in the vicinity of various solid surfaces on heterogeneous ice nucleation using molecular dynamics simulations. Specifically, we simulated heterogeneous ice nucleation on a perfect crystalline surface of platinum and surface with a slit structure at a nanometer scale. We calculated the local diffusivity (LD) as an indicator of DH and found that the correlation between the distribution of LD and the location of critical ice nucleation showed that ice nucleation tends to occur in regions with relatively low LD. In addition to this, by employing nanoslit structures of various widths, we found that the surface width of the slit structure or surrounding substrate where ice nucleation occurs is important for critical nucleation.