A comparison of interatomic potentials for noble gases

Abstract

Prediction of transport properties of noble gases requires the calculation of collision integrals, which depend on interatomic potentials as the input. However the accuracy of transport properties depends largely on the accuracy of interaction potentials. So different interatomic potentials of noble gases are compared in order to get the accurate transport properties. The forms and characteristics of Lennard-Jones, exponential repulsive, Hartree-Fock-Dispersion-B (HFD-B), and phenomenological model potentials that are used to describe the atomic interactions between noble gases are analyzed in this paper. Then the calculation method of transport properties is presented. Viscosities and thermal conductivities of noble gases based on these four potentials are obtained using Chapman-Enskog method in the temperature range for computation from 300 to 5000 K. It can be seen from the results that the interaction potentials have a great influence on the calculated results of transport properties. There are great differences between the results obtained using different interaction potentials. These differences of the calculated results can be explained according to the performance of interaction potentials. Results calculated with Lennard-Jones potential are always much lower in the high temperature range due to its overestimated repulsive part, and the exponential repulsive potential gives unreasonable results at low temperatures because there is no attractive well in this potential. Therefore, the accurate interatomic potentials for noble gases can be obtained only by comparing the calculated results with published experimental and theoretical data of other researchers. It can be found that the results obtained by HFD-B potential agree well with previously experimental and theoretical data. So it is apparent that the HFD-B potential in light of Hartree-Fock repulsion and dispersion theory can provide a realistic description of the trends and features of interatomic potentials, allowing accurate theoretical calculations to be made for transport properties of noble gases.