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Improved First-Principles Calculation of the Third Virial Coefficient of Helium
Giovanni Garberoglio1, Michael R Moldover2, Allan H Harvey3
1Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, Via Sommarive 18, I-38123 Povo, Italy.
Abstract:
We employ state-of-the-art pair and three-body potentials with path-integral Monte Carlo (PIMC) methods to calculate the third density virial coefficient C(T) for helium. The uncertainties are much smaller than those of the best experimental results, and approximately one-fourth the uncertainty of our previous work. We have extended our results in temperature down to 2.6 K, incorporating the effect of spin statistics that become important below approximately 7 K. Results are given for both the (3)He and (4)He isotopes. We have also performed PIMC calculations of the third acoustic virial coefficient γ a; our calculated values compare well with the limited experimental data available. A correlating equation for C(T) of (4)He is presented; differentiation of this equation provides a reliable and simpler way of calculating γ a.
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