Up to fourth virial coefficients from simple and efficient internal-coordinate sampling: application to neon.

Area of Science:

• Computational Chemistry
• Statistical Mechanics
• Atomic Physics

Background:

• Virial coefficients are essential for understanding the equation of state of gases.
• Accurate computation of higher-order virial coefficients is computationally demanding.
• Existing methods struggle with efficiency and accuracy for complex atomic systems.

Purpose of the Study:

• To develop a simple and efficient internal-coordinate importance sampling protocol for Monte Carlo computation of virial coefficients.
• To apply the protocol to calculate second, third, and fourth virial coefficients of neon.
• To assess the significance of four-body contributions and quantum corrections.

Main Methods:

• Proposed a multivariate sampling distribution mimicking the pairwise-additive structure of virial coefficients.
• Employed internal-coordinate importance sampling for Monte Carlo simulations.
• Calculated virial coefficients and equation-of-state data using ab initio potentials for neon.

Main Results:

• The proposed sampling scheme is competitive with routine numerical methods.
• Second, third, and fourth virial coefficients for neon were computed.
• Four-body contributions were found to be insignificant for neon.
• First-order Kirkwood-Wigner quantum corrections were crucial for agreement with experimental data.

Conclusions:

• The developed Monte Carlo protocol offers an efficient and accurate method for computing virial coefficients.
• Quantum corrections are vital for precise predictions, especially at higher temperatures.
• The method shows promise for broader applications in atomic and molecular systems.