Density functional theory for the freezing of soft-core fluids

Area of Science:

• Condensed Matter Physics
• Theoretical Chemistry
• Materials Science

Background:

• Understanding the solid phases of matter is crucial for materials science.
• Soft-core potentials model interactions in various systems, including colloids and polymers.
• Existing theories struggle to accurately predict phase diagrams for all soft-core potentials.

Purpose of the Study:

• To develop a simple density functional theory (DFT) for predicting solid phases of particles with soft-core potentials.
• To validate the DFT's performance using repulsive point Yukawa and Gaussian pair potentials.
• To assess the theory's ability to capture key solid-state transitions.

Main Methods:

• Formulation of a novel, simplified density functional theory.
• Application of the DFT to model systems with repulsive point Yukawa potentials.
• Application of the DFT to model systems with Gaussian pair potentials.
• Comparison of theoretical predictions with established phase diagrams.

Main Results:

• The developed DFT shows qualitative agreement with known phase diagrams for both Yukawa and Gaussian systems.
• The theory successfully accounts for the body-centered cubic (bcc) to face-centered cubic (fcc) solid transitions.
• The DFT captures the phenomenon of re-entrant melting observed in the Gaussian system.

Conclusions:

• The proposed simple density functional theory provides a robust framework for studying solid phases of soft-core systems.
• The theory's success with Yukawa and Gaussian potentials highlights its potential applicability to a wider range of soft interactions.
• This work offers a valuable tool for predicting and understanding phase behavior in soft matter systems.