EXP6 fluids at extreme conditions modeled by two-Yukawa potentials

Area of Science:

• Thermodynamics
• Physical Chemistry
• Computational Fluid Dynamics

Background:

• The EXP6 potential is widely used for modeling fluids, but its complexity can be computationally intensive.
• Developing accurate and efficient representations of fluid potentials is crucial for understanding their behavior under extreme conditions.

Purpose of the Study:

• To develop and validate a two-Yukawa potential model as a computationally efficient representation of the EXP6 fluid.
• To investigate the structural and thermodynamic properties of EXP6 fluids using the two-Yukawa model across different temperature ranges.

Main Methods:

• Utilized molecular simulations to examine the EXP6 fluid.
• Developed a unique mapping of the repulsive part of the EXP6 potential onto a two-Yukawa potential.
• Compared the two-Yukawa model with the EXP6 potential under geochemical (T(geo)) and detonation (T(det)) temperature conditions.

Main Results:

• The local structures of EXP6 and two-Yukawa fluids were found to be practically identical across both temperature ranges.
• Deviations in thermodynamic properties were observed at lower temperatures within the T(geo) range due to potential function differences at intermediate separations.
• At higher temperatures (T(geo) and T(det)), both structural and thermodynamic properties of the two fluids showed strong agreement.

Conclusions:

• The two-Yukawa potential provides a highly accurate and efficient representation of EXP6 fluids, particularly at supercritical temperatures and high pressures.
• This simplified model is suitable for applications in geochemistry and detonation physics where accurate fluid behavior prediction is essential.
• The model's validity is confirmed by its ability to reproduce the structural and thermodynamic characteristics of the EXP6 fluid under diverse extreme conditions.