Phase behavior of attractive and repulsive ramp fluids: integral equation and computer simulation studies

Area of Science:

• Thermodynamics
• Computational Physics
• Materials Science

Background:

• Understanding fluid phase behavior is crucial for materials science and chemical engineering.
• Investigating particle interactions, particularly attractive and repulsive forces, reveals complex phase diagrams.

Purpose of the Study:

• To explore the phase behavior and thermodynamic anomalies of a fluid with a two-scale ramp potential.
• To compare the effects of attractive forces versus purely repulsive forces on fluid properties.

Main Methods:

• Utilizing computer simulations to model particle interactions.
• Employing a thermodynamically self-consistent integral equation for theoretical analysis.

Main Results:

• Both simulation and integral equation methods predict liquid-liquid demixing due to attractive forces.
• A gas-liquid transition and a fluid-solid transition were observed, creating a complex phase diagram.
• Solidification occurred in the repulsive ramp fluid but inhibited fluid-fluid separation.

Conclusions:

• Attractive forces in the two-scale ramp potential lead to rich phase behavior, including liquid-liquid demixing.
• The interplay between attractive and repulsive forces significantly influences the emergent phase diagram and transitions.
• The study highlights the importance of interaction potentials in determining fluid properties.