Effect of nitrogen molecules on the growth kinetics at the interface between a (111) plane of cubic ice and water.

Abstract

The molecular-scale growth kinetics of ice from water in the presence of air molecules are still poorly understood, despite their importance for understanding ice particle formation in nature. In this study, a molecular dynamics simulation is conducted to elucidate the molecular-scale growth kinetics at the interface between a (111) plane of cubic ice and water in the presence of N2 molecules. Two potential models of N2 molecules with and without atomic charges are examined. For both models, N2 molecules bind stably to the interface for a period of 1ns or longer, and the stability of the binding is higher for the charged model than for the noncharged model. Free-energy surfaces of an N2molecule along the interface and along an ideal (111) plane surface of cubic ice suggest that for both models, the position where an N2molecule binds stably is different at the interface and on the ideal plane surface, and the stability of the binding is much higher for the interface than for the ideal plane surface. For both models, stacking-disordered ice grows at the interface, and the formation probability of a hexagonal ice layer in the stacking-disordered ice is higher for the charged model than for the uncharged model. The formation probability for the hexagonal ice layer in the stacking-disordered ice depends not only on the stability of binding but also on the positions where N2 molecules bind to the underlying ice and the number of N2 molecules that bind stably to the underlying ice.