  Freezing of water is arguably one of the most common phase transitions on
Earth and almost always happens heterogeneously. Despite its importance, we
lack a fundamental understanding of what makes substrates efficient ice
nucleators. Here we address this by computing the ice nucleation (IN) ability
of numerous model hydroxylated substrates with diverse surface hydroxyl (OH)
group arrangements. Overall, for the substrates considered, we find that
neither the symmetry of the OH patterns nor the similarity between a substrate
and ice correlate well with the IN ability. Instead, we find that the OH
density and the substrate-water interaction strength are useful descriptors of
a material's IN ability. This insight allows the rationalization of ice
nucleation ability across a wide range of materials, and can aid the search and
design of novel potent ice nucleators in the future.
