Temperature dependence of ice critical nucleus size

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Physics

Background:

• Supercooled water is thermodynamically unstable and prone to freezing.
• Spontaneous ice nucleation is a critical process in various natural and industrial applications.
• Observing homogeneous ice nucleation in atomistic simulations remains computationally challenging.

Purpose of the Study:

• To investigate the relationship between critical nucleus size and temperature during ice growth from supercooled water.
• To elucidate the molecular mechanisms underlying ice nucleation.
• To reconcile simulation findings with experimental observations of water supercooling.

Main Methods:

• Molecular dynamics simulations were employed to study ice growth.
• Simulations were conducted with varying initial conditions to explore different temperature regimes.
• Analysis focused on identifying the size of critical ice nuclei formed.

Main Results:

• A quantitative relationship between critical nucleus size and temperature was established.
• Ice embryos require hundreds to thousands of molecules for macroscopic crystallization, even under significant supercooling.
• The study highlights the substantial energetic barriers to spontaneous ice nucleation.

Conclusions:

• The large critical nucleus size explains the difficulty in observing spontaneous ice nucleation in atomistic simulations.
• Findings provide insights into the experimental feasibility of supercooling water droplets.
• The research contributes to a fundamental understanding of phase transitions in water.