Temperature dependence of crystal growth of hexagonal ice (Ih)

Abstract

The transformations between water and ice have many implications across numerous fields of study. A better understanding of this process would benefit many areas of science and technology such as medicine, biology, and atmospheric and material sciences. In the present work the temperature dependence of the rate of growth (melting) of the basal face of hexagonal ice I_h and the effect of system size are investigated in molecular dynamics simulations. Using an effective pair potential model of water, systems are studied over temperatures ranging from T_M − 40 to T_M +16 K, where T_M is the melting temperature of the model. It is found that the growth rates reach a maximum value of 0.7 Å ns⁻¹ (7 cm s⁻¹) at about 12 K below the melting temperature. A noticeable effect of the system size on the melting temperature and ice growth rates is observed; it is shown that the size effect arises in smaller systems due to the artificial ordering under periodic conditions. The decrease in melting entropy in the smallest system by 0.4 J (mol K)⁻¹ relative to the largest system results in an up-shift in the melting temperature by about 2 K. An almost 60% increase in the maximum growth rate is observed for the smallest system.