Heterogeneous Ice Nucleation Induced by Electric Fields

Heterogeneous ice nucleation is an important phenomenon in the physical environment influencing atmospheric and biological processes. Despite this relevance, the mechanism of heterogeneous ice nucleation is not understood at the microscopic level, and what exactly constitutes a good ice nucleus is an open question. Employing molecular dynamics simulations, we demonstrate that an electric field, which acts very near a surface, can create an effective ice nucleus in models of supercooled liquid water. To serve as an ice nucleus, the field must polarize only a very thin water layer (similar to 10 angstrom), and the field strength required is realistic on the relevant length scale. Our results support the idea that local electric fields could play a major role in heterogeneous ice nucleation, particularly for the very rough particles with many surface structure variations, that serve as ice nuclei in environmentally realistic situations.