Phase transitions in highly asymmetric binary hard-sphere fluids: Fluid-fluid binodal from a two-component mixture...

Area of Science:

• Statistical Mechanics
• Thermodynamics
• Soft Matter Physics

Background:

• Understanding phase behavior in multi-component systems is crucial for materials science.
• Hard-sphere models provide a fundamental basis for studying fluid thermodynamics.
• Previous theoretical methods had limitations in describing dense fluid regions.

Purpose of the Study:

• To compute fluid-fluid binodals for binary hard-sphere mixtures.
• To validate a new theoretical approach based on fundamental measure theory and mean spherical approximation.
• To compare results with single-component systems and assess the method's applicability.

Main Methods:

• Utilizing the two-component Ornstein-Zernike equation with a novel fundamental measure functional-mean spherical approximation closure.
• Calculating fluid-fluid binodals for binary hard-sphere mixtures.
• Comparing results with one-component fluid of large spheres.

Main Results:

• Successfully computed fluid-fluid binodals, particularly in dense fluid regions previously inaccessible.
• Observed general trends consistent with hard-sphere potentials.
• Detected minor differences between binary mixture and effective one-component descriptions.

Conclusions:

• The proposed theoretical method accurately describes fluid-fluid binodals in hard-sphere mixtures.
• The equivalence of binary mixture and effective one-component descriptions is validated for size ratios R >= 8.5.
• This work advances theoretical tools for studying phase behavior in complex fluids.