Third density and acoustic virial coefficients of helium isotopologues from ab initio calculations

Published

June 24, 2024

Author(s)

Daniele Binosi, Giovanni Garberoglio, Allan H. Harvey

Abstract

Improved two-body and three-body potentials for helium have been used to calculate from first principles the third density and acoustic virial coefficients for both 4He and 3He. For the third density virial coefficient C(T), uncertainties have been reduced by a factor of 4–5 compared to the previous state of the art; the accuracy of first-principles C(T) now exceeds that of the best experiments by more than two orders of magnitude. The range of calculations has been extended to temperatures as low as 0.5 K. For the third acoustic virial coefficient γa(T), we applied the Schlessinger Point Method, which can calculate γa and its uncertainty based on the C(T) data, overcoming some limitations of direct path-integral calculation. The resulting γa are calculated at temperatures down to 1 K; they are consistent with available experimental data but have much smaller uncertainties. The first-principles data presented here will enable improvement of primary temperature and pressure metrology based on gas properties.

Citation

The Journal of Chemical Physics

Volume

160

Issue

24

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0217852

Local Download

Keywords

helium, thermodynamics, virial coefficients

Citation

Binosi, D. , Garberoglio, G. and Harvey, A. (2024), Third density and acoustic virial coefficients of helium isotopologues from ab initio calculations, The Journal of Chemical Physics, [online], https://doi.org/10.1063/5.0217852, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957828 (Accessed October 10, 2025)