Largest Smooth Interfacial-Water Domains Predict Heterogeneous Ice Nucleation on Rough Surfaces

Understanding heterogeneous ice nucleation on solid surfaces is essential for controlling water freezing in natural and technological contexts. Using molecular dynamics simulations, we investigated how the nanoscale roughness of surfaces regulates heterogeneous ice nucleation. Our results indicate that ice nucleation preferentially occurs on locally flat surface regions that are capable of generating smooth, ordered interfacial-water domains, which act as active sites for ice formation. The maximum size of these smooth interfacial-water domains serves as a practical descriptor for the nucleation capability of a surface. In contrast, atomic-scale protrusions, cavities, and other defects in surfaces disrupt the smoothness of interfacial water and thereby hinder nucleation. These results reveal that the ice-nucleation ability of rough solid surfaces shows a strong association with their ability to organize interfacial water into sufficiently large and ordered domains, rather than with average surface roughness, and provide new insights for the rational design of anti-icing and ice-promoting materials.