Local density approach for modeling fluids with density-dependent interactions

Area of Science:

• Physics
• Physical Chemistry
• Computational Fluid Dynamics

Background:

• A simple fluid with a density-dependent pair potential exhibits vapor-liquid and liquid-liquid phase transitions.
• Standard simulation methods struggle to define stability boundaries due to density fluctuations frustrating phase separation.

Purpose of the Study:

• To deeply explore the behavior of this specific fluid.
• To introduce and detail a local density simulation technique for accurate stability boundary determination.
• To highlight the general significance for density-dependent potentials.

Main Methods:

• Development and application of a simulation procedure utilizing local densities.
• Analysis of thermodynamic states where phase separation is influenced by density fluctuations.
• Comparison with integral equations and global density simulations.

Main Results:

• The local density simulation technique accurately defines stability boundaries.
• Discrepancies were observed between thermodynamically estimated critical points and divergent correlations in global simulations.
• The potential drives phase separation, which is counteracted by density fluctuations.

Conclusions:

• The proposed local density simulation method is crucial for accurately characterizing phase transitions in fluids with density-dependent potentials.
• Findings have broad implications for understanding liquid metals and charge-stabilized colloids.
• Accurate stability boundary definition is essential for systems with frustrated phase separation.