Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Path-integral calculation of the fourth virial coefficient of helium isotopes

Published

Author(s)

Giovanni Garberoglio, Allan H. Harvey

Abstract

We use the path-integral Monte Carlo (PIMC) method and state-of-the-art two-body and three-body potentials to calculate the fourth virial coefficient D(T) of 4He and 3He as a function of temperature from 2.6 K to 2000 K. We derive expressions for the contributions of exchange effects due to the bosonic or fermionic nature of the helium isotope; these effects have been omitted from previous calculations. The exchange effects are relatively insignificant for 4He at the temperatures considered, but for 3He they are necessary for quantitative accuracy below about 4 K. Our results are consistent with previous theoretical work (and with some of the limited and scattered experimental data) for 4He; for 3He there are no experimental values and this work provides the first values of D(T) calculated at this level. The uncertainty of the results depends on the statistical uncertainty of the PIMC calculation, the estimated effect of omitting four-body and higher terms in the potential energy, and the uncertainty contribution propagated from the uncertainty of the potentials. At low temperatures, the uncertainty is dominated by the statistical uncertainty of the PIMC calculations, while at high temperatures the uncertainties related to the three-body potential and to omitted higher-order contributions become dominant.
Citation
The Journal of Chemical Physics
Volume
154
Issue
10

Keywords

helium, quantum effects, virial coefficients

Citation

Garberoglio, G. and Harvey, A. (2021), Path-integral calculation of the fourth virial coefficient of helium isotopes, The Journal of Chemical Physics, [online], https://doi.org/10.1063/5.0043446, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931391 (Accessed August 10, 2022)
Created March 8, 2021, Updated April 6, 2021