Three-body nonadditive potential for argon with estimated uncertainties and third virial coefficient

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Computational Chemistry

Background:

• Accurate interatomic potentials are crucial for understanding gas properties.
• Previous three-body potentials for argon had limitations in accuracy and temperature range.

Purpose of the Study:

• To compute a highly accurate three-body nonadditive interaction energy for argon atoms.
• To derive an analytic three-body potential for argon.
• To calculate the third virial coefficient, C(T), of argon, incorporating quantum effects.

Main Methods:

• Coupled cluster methods up to CCSDT(Q) with core correlation and relativistic effects.
• Analytic function fitting to calculated interaction energies.
• Path-integral Monte Carlo simulations for C(T) calculations.
• Propagation of uncertainties from potential to C(T).

Main Results:

• The most accurate three-body argon potential to date was developed.
• Third virial coefficients, C(T), were computed from 80 to 10000 K.
• Calculated C(T) values show smaller uncertainties than available experimental data, especially at higher temperatures.
• Results are consistent with existing experimental data where overlap exists.

Conclusions:

• The new three-body potential significantly advances the accuracy of argon interaction modeling.
• The computed C(T) values provide a reliable benchmark for gas property predictions.
• This work highlights the power of high-level quantum chemical calculations and advanced simulation methods.