High and low density patches in simulated liquid water

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Liquid water exhibits complex structural dynamics.
• Understanding water's heterogeneity is crucial for various chemical and biological processes.
• The role of empty space in water's structure is not fully elucidated.

Purpose of the Study:

• To investigate the nature of structural heterogeneities in liquid water.
• To characterize the empty space within the hydrogen bond network.
• To correlate void formation with density fluctuations and molecular arrangements.

Main Methods:

• Molecular dynamics simulations were employed.
• Characterization of empty space morphology (spherical to fractal-like voids).
• Analysis of density fluctuations and length-scales (0.3-2 nm).

Main Results:

• Density fluctuations create diverse empty space morphologies.
• Identification of low and high-density patches at multiple length-scales.
• Void formation is coupled to hydrogen-bonded ring topology fluctuations.
• High-density patches show increased tetrahedrality, consistent with hydrophobic effect predictions.

Conclusions:

• Structural heterogeneities in liquid water are intrinsically linked to the empty space within its hydrogen bond network.
• The morphology and distribution of these voids provide insights into water's dynamic structure.
• Findings contribute to a deeper understanding of water's behavior in chemical and physical systems.