Anisotropic surface melting of an ice crystal and its relationship to growth forms

Surface structures of ice crystals are discussed on the basis of experiments and molecular dynamics simulation. Experimental results showed that anisotropic surface melting can occur on the {0001}- and {10 (1) over bar 0}- faces of an ice crystal at temperatures just below the bulk melting point. Molecular dynamics simulations of ice surfaces were also carried out in order to examine the dynamic properties of surface melting. Anisotropic temperature dependence on the thickness of the quasiliquid layer (qll), which was consistent with the experimental results, was confirmed between both the {0001}- and {10 (1) over bar 0}-faces. Self-diffusion coefficients, which were estimated from the translational movements of water molecules in the quasiliquid layer, indicate that the dynamic properties of the quasiliquid layer change significantly with changes in the depth from the qll surface. Finally, growth forms of ice crystals are discussed in connection with anisotropic surface melting.