Gas-liquid phase transition in a binary mixture with an interaction that creates constant density profiles.

Area of Science:

• Statistical Mechanics
• Soft Matter Physics
• Computational Physics

Background:

• Hard sphere fluids exhibit long-ranged density oscillations when a single test particle is fixed.
• Classical density functional theory (DFT) is a powerful tool for studying fluid behavior.
• The influence of finite-range repulsive potentials on these oscillations has been largely unexplored.

Purpose of the Study:

• To investigate the effect of a finite-range, purely repulsive external potential on density oscillations in a hard sphere fluid.
• To explore the application of this potential as an inter-component interaction in a binary hard-sphere mixture.
• To determine if this interaction can induce phase transitions in the mixture.

Main Methods:

• Utilizing classical density functional theory (DFT) to model the hard sphere fluid.
• Introducing a finite-range, purely repulsive potential to modify particle interactions.
• Analyzing the induced effective interaction in a binary mixture and its potential to cause phase transitions.

Main Results:

• A finite-range, purely repulsive potential, when combined with a fixed hard sphere, can completely suppress long-ranged density oscillations.
• In a binary hard-sphere mixture, this potential acting as an inter-component interaction induces an effective potential qualitatively similar to the Asakura-Oosawa-Vrij potential.
• This induced effective interaction can drive a liquid-gas phase transition in one of the components.

Conclusions:

• Finite-range repulsive potentials offer a simple yet effective means to control particle distribution in hard sphere systems.
• The Asakura-Oosawa-Vrij-like effective interaction generated in binary mixtures highlights the potential for designing novel phase behaviors.
• This research opens avenues for further exploration of tailored interactions in complex fluid systems and their phase transitions.