Interplay between translational diffusion and large-amplitude angular jumps of water molecules

Area of Science:

• Physics and Chemistry
• Molecular Dynamics Simulations
• Water Molecular Dynamics

Background:

• Understanding microscopic mechanisms of water molecular translational diffusion is complex.
• Investigating the interplay between translational diffusion and large-amplitude angular jumps in bulk water.

Purpose of the Study:

• To elucidate the coupling between water molecule angular jumps and translational diffusion.
• To reveal the contribution of cooperative rotational jumps to translational diffusion.

Main Methods:

• Utilizing molecular dynamics simulations to study water behavior.
• Performing control simulations with modified hydrogen bond strengths.

Main Results:

• Large-amplitude angular jumps are tightly coupled with translational diffusion.
• Concurrent rotational jumps of neighboring molecules induce inter-basin translational jumps, contributing to fast diffusion.
• Positional heterogeneity in translational diffusion was observed, with neighbors of diffusing molecules more likely to exhibit similar diffusion.

Conclusions:

• Cooperative molecular rotations drive fast translational diffusion in water.
• Water's hydrogen bond network enables faster diffusion than simple liquids like Lennard-Jones particles.
• The study enhances the microscopic understanding of water diffusion mechanisms.