Molecular dynamics simulations of ice nucleation by electric fields

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Physics

Background:

• Heterogeneous ice nucleation is crucial in various natural and industrial processes.
• Understanding the factors influencing ice formation at surfaces is essential for controlling phase transitions.
• The role of electric fields in ice nucleation has been hypothesized but requires detailed investigation.

Purpose of the Study:

• To investigate the effect of electric fields on heterogeneous ice nucleation using molecular dynamics simulations.
• To determine the influence of electric field strength and its spatial extent on ice nucleation.
• To explore the impact of temperature on field-induced ice nucleation.

Main Methods:

• Molecular dynamics simulations of water molecules near a surface under an applied electric field.
• Utilized two distinct water models: the six-site model and the TIP4P/Ice model.
• Analyzed the resulting ice structures, nucleation temperatures, and required field parameters.

Main Results:

• A surface electric field acts as an effective catalyst for ice nucleation in supercooled water for both models.
• Ferroelectric cubic ice nucleates at the surface, with dipole-disordered cubic ice growing outwards.
• Field-induced nucleation was observed up to 280 K (six-site model) and 270 K (TIP4P/Ice model).
• Effective field strengths ranged from 1.5 × 10^9 V/m (20 Å extent) to 3.5 × 10^9 V/m (10 Å extent).

Conclusions:

• Localized electric fields of realistic strength can effectively nucleate ice near the freezing point.
• This finding supports the significant role of local electric fields in heterogeneous ice nucleation, particularly on rough surfaces.
• The study provides a molecular-level understanding of electric field effects on water phase transitions.