Entropy of simple fluids with repulsive interactions near freezing

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Physical Chemistry

Background:

• Estimating thermodynamic properties of liquids, particularly entropy, is a significant challenge.
• Accurate entropy estimation models are crucial for understanding interatomic interactions and liquid behavior.

Purpose of the Study:

• To develop and apply a novel method for estimating the excess entropy of simple liquids near the liquid-solid phase transition.
• To investigate the relationship between liquid thermodynamics and collective mode properties.

Main Methods:

• A variant of cell theory is proposed, focusing on the connection between liquid thermodynamics and collective modes.
• The method is applied to inverse-power-law fluids with varying repulsive interaction strengths (n=1, 6, 12, ∞).
• The Lennard-Jones potential was also used for comparison.

Main Results:

• The proposed method provides reasonably good agreement with "exact" results for inverse-power-law fluids at high densities.
• The method's applicability is linked to the excess entropy value itself.
• Lower accuracy was observed when applied to the Lennard-Jones potential.

Conclusions:

• The developed cell theory variant offers a viable approach for estimating excess entropy in simple liquids with isotropic repulsive interactions.
• The findings are relevant for diverse systems like liquid metals, macromolecular systems, proteins, and colloidal suspensions.
• Further refinement may be needed for potentials like the Lennard-Jones potential.