Third and fourth density and acoustic virial coefficients of neon from first-principles calculations

TL;DR

This study uses first-principles path-integral Monte Carlo calculations with advanced ab initio potentials to accurately determine neon's third and fourth virial coefficients over a wide temperature range.

Contribution

It introduces a highly accurate ab initio pair and many-body potentials for neon, enabling precise calculation of virial coefficients with rigorously propagated uncertainties.

Findings

Calculated virial coefficients have smaller uncertainties than most experimental data.

Developed a nonadditive three-body potential based on extensive supermolecular calculations.

Provided temperature-dependent third and fourth virial coefficients for neon from 10 to 5000 K.

Abstract

The third and fourth density and acoustic virial coefficients of neon were determined at temperatures between 10 and 5000 K from first principles employing the path-integral Monte Carlo (PIMC) approach. For these calculations, we used the pair potential of Hellmann $\textit{et al.}$ [J. Chem. Phys. 154, 164304 (2021)], which is based on supermolecular $\textit{ab initio}$ calculations with basis sets of up to octuple-zeta quality and levels of theory up to coupled cluster with single, double, triple, quadruple, and perturbative pentuple excitations [CCSDTQ(P)]. The potential also accounts for relativistic, retardation, and post-Born$-$Oppenheimer effects and is provided with reliable uncertainty estimates. To incorporate nonadditive interactions, we developed a nonadditive three-body potential based on extensive supermolecular CCSD(T), CCSDT, and CCSDT(Q) calculations with basis sets of up to sextuple-zeta quality. This potential also accounts for relativistic effects. The very small nonadditive four-body contributions to the fourth virial coefficients were considered using a relatively simple nonadditive four-body potential based on supermolecular CCSD(T) calculations. We calculated the third and fourth density and third acoustic virial coefficients directly by PIMC and the fourth acoustic virial coefficient indirectly using thermodynamic relations between the density and acoustic virial coefficients. The uncertainties of the pair potential and those estimated for our nonadditive three-body potential were rigorously propagated in the PIMC calculations into uncertainties for the virial coefficients. These uncertainties are distinctly smaller than those of almost all of the corresponding experimental virial coefficient data.