The growth kinetics of ice are modeled using the Water Potential from Adaptive Force Matching for Ice and Liquid （WAIL） potential with molecular dynamics. The all-atom WAIL model provides a good description of the p...The growth kinetics of ice are modeled using the Water Potential from Adaptive Force Matching for Ice and Liquid （WAIL） potential with molecular dynamics. The all-atom WAIL model provides a good description of the properties of both ice and liquid with an equilibrium temperature of 270 K at 1 bar. The growth kinetics captured by this model can thus reflect those of real ice. Our simulation indicates that the growth rate of ice on the basal plane is fastest at approximately 20 K supercooling, consistent with experimental findings, where the growth rate increases monotonically as the supercooling increases to 18 K. The key factors that control the growth kinetics leading to the optimal growth temperature are investigated. The simulation revealed a bilayer-by-bilayer growth mechanism on the basal plane that proceeds in two steps. Whereas water molecules lose translational motion and become ice-like quickly, the establishment of orientational order to form ice is a slow and activated process. Enhanced by the templating effect of sublayers, the rapid reduction in translational motion in the formation of the prefreezing layer might explain the significantly faster growth rate relative to the nucleation rate of water. Whereas remelting of the prefreezing layer is observed at low supercooling and may be responsible for the lower growth rate close to the melting temperature, the slow orientational ordering of the prefreezing layer into the final ice conformation is partly responsible for the reduced growth rate at deeper supercooling.展开更多
基金This work was supported by the National Basic Research Program of China under Grant No. 2015CB856801, the National Natural Science Foundation of China under Grant Nos. 11525520 and 11290162/A040106, and the National Key R＆D Program under Grant No. 2016YFA0300901. The computer re- sources for this study were provided by the Arkansas High Per- formance Computational Center through grant MRI-R2 0959124 provided by the NSF of USA.
文摘The growth kinetics of ice are modeled using the Water Potential from Adaptive Force Matching for Ice and Liquid （WAIL） potential with molecular dynamics. The all-atom WAIL model provides a good description of the properties of both ice and liquid with an equilibrium temperature of 270 K at 1 bar. The growth kinetics captured by this model can thus reflect those of real ice. Our simulation indicates that the growth rate of ice on the basal plane is fastest at approximately 20 K supercooling, consistent with experimental findings, where the growth rate increases monotonically as the supercooling increases to 18 K. The key factors that control the growth kinetics leading to the optimal growth temperature are investigated. The simulation revealed a bilayer-by-bilayer growth mechanism on the basal plane that proceeds in two steps. Whereas water molecules lose translational motion and become ice-like quickly, the establishment of orientational order to form ice is a slow and activated process. Enhanced by the templating effect of sublayers, the rapid reduction in translational motion in the formation of the prefreezing layer might explain the significantly faster growth rate relative to the nucleation rate of water. Whereas remelting of the prefreezing layer is observed at low supercooling and may be responsible for the lower growth rate close to the melting temperature, the slow orientational ordering of the prefreezing layer into the final ice conformation is partly responsible for the reduced growth rate at deeper supercooling.
