Effective Nucleation Size for Ice Crystallization.

Despite the apparent simplicity of water molecules, the kinetics of ice nucleation under natural conditions can be surprisingly intricate. Previous studies have yielded critical nucleation sizes that vary widely due to differences in experimental and computational approaches. In our investigation, we employed all-atom molecular dynamics simulations to explore spontaneously grown and ideal ice nuclei, revealing significant disparities in their kinetics. Notably, nucleation defects challenge the applicability of the classical nucleation theory (CNT) to spontaneously grown ice nuclei. To address this, we propose a generalized nucleation theory that effectively describes the kinetics of ice crystal nucleation across diverse conditions. The kinetics of ice nuclei, as characterized by the "corrected" critical nucleus size, follow a linear law akin to that assumed by CNT. This generalized nucleation theory also provides insights for studying the kinetics of other crystalline materials.