Can molecular simulations reliably compare homogeneous and heterogeneous ice nucleation?

Area of Science:

• Computational chemistry
• Materials science
• Thermodynamics

Background:

• Simulations of water's phase behavior require accurate modeling of intermolecular interactions.
• Different truncation schemes for potentials are used in homogeneous versus heterogeneous systems.
• This discrepancy can lead to inaccuracies in predicting properties like ice melting points.

Purpose of the Study:

• To assess the impact of different truncation schemes on simulating water in homogeneous and inhomogeneous environments.
• To investigate the effect of the "cut-and-shift" Lennard-Jones potential on ice Ih melting temperature.
• To re-evaluate the magnitude of enhancements observed in heterogeneous nucleation.

Main Methods:

• Explicit free energy calculations were performed.
• A mean field analysis was employed.
• Literature data for homogeneous ice nucleation at negative pressures were analyzed.

Main Results:

• The "cut-and-shift" truncation scheme for the Lennard-Jones potential systematically increases the melting temperature of ice Ih.
• This effect is analogous to changes in pressure.
• Potential overestimation of heterogeneous nucleation enhancements by several orders of magnitude was suggested.

Conclusions:

• The choice of truncation scheme significantly impacts the simulated melting temperature of ice Ih.
• Standard simulation methods may overestimate the benefits of heterogeneous nucleation.
• Careful consideration of potential truncation is crucial for accurate water simulations.