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Title: Homogeneous ice nucleation rate of deeply supercooled water
Plain: Pure water droplets can stay liquid well below 0 C because ice needs a seed to start. How fast ice appears on its own at very low temperature, and which form of ice appears first, is still uncertain.
Precise: Determine the homogeneous ice nucleation rate $J(T)$ in pure H2O between about 230 and 240 K, where measurements by different techniques disagree by several orders of magnitude and simulations (seeding with TIP4P/Ice and similar models) depend on CNT-based extrapolation. Decide whether CNT with a temperature-dependent ice-water interfacial free energy $\gamma(T)$ reproduces $J(T)$, and confirm whether the critical nucleus is stacking-disordered ice.
Settled by: Mutually consistent measurements of J(T) by independent techniques and simulations with an accurate water model that reproduce them without fitted interfacial free energies.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: partially-resolved
Status note: Seeding simulations reproduce measured rates within several orders of magnitude and indicate stacking-disordered critical nuclei; precise agreement is lacking (2026).
Posed since: (empty)