MD Simulation of the Ice-Water Interface

The molecular-scale structures and dynamic properties of ice-water interfaces and the growth mechanism at the interfaces are also important research subjects that should be investigated by computer simulations. Karim and Haymet [73] performed a 0.14ns MD simulation for the interface of the basal plane at 240 K using the T1P4P model. Simulation results indicated that the interface has a diffuse structure throughout the thickness of several molecular layers. The thickness of the interface was approximately 1 nm. 

Nada and Furukawa [74] performed a 0.1 ns MD simulation for the interfaces of basal and prismatic planes at 230 K using the T1P4P model. Simulation results indicated that the thickness of the interface is larger for the basal plane than that for the prismatic plane. The simulation results also indicated that the diffusion coefficient of H2O molecules in water near the interface is smaller for the prismatic plane than that for the basal plane. This smaller diffusion coefficient for the prismatic plane than that for the basal plane was thought to originate from the molecularly rough structure of the interface for the prismatic plane. 

If the simulation is performed at T 230 K with a longer run, the growth of several molecular layers of ice, which is sufficient to determine R, might occur on the interface. However, the diffusion coefficient of Hj O molecules in water is much 

We discuss here the reason for the anisotropy in R, the interface structure, and the growth mechanism among the planes. The anisotropic R can be roughly explained from the difference in the arrangement of lattice sites on the surface among the planes [79]. Each H2O molecule in bulk ice has four nearest neighboring HjO molecules and, hence, makes four HBs. However, for all of the basal, prismatic, and secondary prismatic planes, an H2O molecule attached to a lattice site on the ice plane makes only one HB. Therefore, the attached H2O molecule is much less stable than the H2O molecules in bulk ice and, hence, is difficult to be stably captured into the lattice site. 

Black- and gray-colored atoms lie on two adjacent planes, (b) Schematic illustrations of H O molecules attached to the lattice sites on the surface. 

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