Effects of convex surface roughness on heterogeneous ice nucleation

In this work, we investigate the effects of convex surface roughness on heterogeneous ice nucleation through molecular dynamics simulations. Graphene surfaces with sawtooth structures are considered, and the ice nucleation rates are calculated by varying the vertex angle of the sawtooth structures. It is found that the ice nucleation rate is always suppressed by surface roughness regardless of the vertex angle. As the vertex angle is varied, the space between two adjacent ridges of the sawtooth roughness may or may not match the basic structure of ice, which leads to the variation in the free energy barrier for ice nucleation and, consequently, causes the ice nucleation rate to change by two orders of magnitude.