Intermolecular Potential-Based Equations of State from Molecular Simulation and Second Virial Coefficient Properties

Area of Science:

• Physical Chemistry
• Thermodynamics
• Computational Chemistry

Background:

• Equations of state are essential for predicting thermodynamic properties.
• Accurate prediction of the second virial coefficient (B) is vital for understanding gas behavior.
• The Boyle temperature (T_B) and temperature maximum (T_max) are key parameters influencing B.

Purpose of the Study:

• To evaluate the importance of T_B and T_max in intermolecular potential-based equations of state.
• To assess the accuracy of Lennard-Jones equations of state in predicting B behavior across different temperatures.
• To identify criteria for improving future equations of state.

Main Methods:

• Comparison of T_B, T_max, and B vs T data from Lennard-Jones equations of state with exact theoretical values.
• Analysis of equation of state performance across low (T ≤ T_B), mid (T_B < T ≤ T_max), and high (T ≫ T_max) temperatures.
• Development of polynomial relationships for B using exact data over various temperature ranges.

Main Results:

• Most equations of state accurately predicted T_B, but struggled with T_max.
• Accurate prediction of both T_B and T_max correlated with accurate B prediction across all temperatures.
• Mecke et al. and Thol et al. Lennard-Jones equations of state showed superior accuracy.

Conclusions:

• Accurate prediction of T_B and T_max is a critical benchmark for potential-based equations of state.
• The study provides a criterion for developing improved equations of state for accurate second virial coefficient modeling.
• Specific Lennard-Jones equations of state offer significant accuracy improvements.