Accurate internal energy of argon fluid from a state-of-the-art ab initio potential with uncertainty estimations

Abstract

The internal energy of argon fluid is computed using an accurate ab initio potential by molecular dynamics simulations for the temperature range from 90 K to 2000 K and at densities up to 30 mol·L−1. The uncertainty of the calculated internal energy values of this work is evaluated by considering the contributions carefully estimating from the ab initio potential and the simulation method, respectively. Excellent agreement with the NIST data shows that the computed internal energy values of this work in gas phase and supercritical phase can be used as reference data. The deviations for liquid phase are well explained by introducing the corrections for three/many-body interactions from the literature. The computed internal energy values of argon with estimated uncertainties are tabulated in the Supplement material and our results at other temperatures and densities are available upon request.