惰性气体原子间相互作用势比较研究

A comparison of interatomic potentials for noble gases

原子间相互作用势是预测惰性气体输运性质的必要输入条件.文章对描述惰性气体原子间相互作用的Lennard-Jones势、指数排斥势、Hartree-Fock-Dispersion-B(HFD-B)势和唯象势的形式和特点进行了分析.基于Chapman-Enskog方法,计算得到了惰性气体在300—5000 K温度区间内基于四种原子相互作用势的黏性和热导率,并与文献报道的实验和理论计算结果进行了比较.研究结果表明,基于Hartree-Fock排斥理论与色散理论发展起来的HFD-B势能够合理反映惰性气体原子相互作用的趋势与特征,因而可以较好地预测惰性气体的宏观输运性质.

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.