Bridging classical nucleation theory and molecular dynamics simulation for homogeneous ice nucleation

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Physics

Background:

• Ice nucleation is crucial for water freezing across natural phenomena.
• Classical nucleation theory (CNT) describes nucleation via critical nuclei but lacks experimental verification for quantitative predictions.
• Molecular dynamics (MD) simulations offer a method to test CNT's accuracy.

Purpose of the Study:

• To quantitatively compare CNT predictions with MD simulations for homogeneous ice nucleation in water.
• To identify factors contributing to discrepancies between CNT and MD in nucleation rate predictions.
• To establish a relationship between CNT and MD for predicting ice nucleation.

Main Methods:

• Utilized MD simulations to determine physical properties of water/ice (density, chemical potential, diffusion).
• Employed thermodynamic assumptions and capillarity approximation for CNT interfacial free energy calculations.
• Compared CNT predictions with brute-force and forward flux sampling MD simulations.

Main Results:

• MD and CNT predicted critical ice cluster sizes were found to be consistent.
• CNT predicted nucleation rates were higher than MD-predicted values by up to three orders of magnitude.
• Stacking-disordered ice structures, cluster asphericity, interfacial free energy uncertainty, and kinetic attachment rates explain rate discrepancies.

Conclusions:

• MD simulations validate CNT's prediction of critical cluster sizes for homogeneous ice nucleation.
• Discrepancies in nucleation rates highlight the importance of ice structure and interfacial properties.
• This study bridges CNT and MD, improving the predictive power for water freezing phenomena.