  Heterogeneous ice growth exhibits a maximum in freezing rate arising from the
competition between kinetics and the thermodynamic driving force between the
solid and liquid states. Here, we use molecular dynamics simulations to
elucidate the atomistic details of this competition, focusing on water
properties in the interfacial region along the secondary prismatic direction.
The crystal growth velocity is maximized when the efficiency of converting
interfacial water molecules to ice, collectively known as the attachment
kinetics, is greatest. We find water molecules that contact the intermediate
ice layer in concave regions along the atomistically roughened surface are more
likely to freeze directly. The increased roughening of the solid surface at
large undercoolings consequently plays an important limiting role on the rate
of ice growth, as water molecules are unable to integrate into increasingly
deeper surface pockets. These results provide insights into the molecular
mechanisms for self-assembly of solid phases that are important in many
biological and atmospheric processes.
