广义Morse流体解析状态方程及对氮的应用

 根据Ross变分微扰理论以及硬球流体Percus-Yevick（PY） 径向分布函数表达式，建立了广义Morse势流体的解析状态方程。与模拟结果的比较一方面证实了广义Morse 势模型的合理性；另一方面表明了解析Ross变分微扰理论的精度相当或略好于非解析的Weeks-Chandler-Anderson （mWCA）理论，而优于复杂的优化超网络链积分方程理论（RHNC）。该解析状态方程被应用于拟合处于环境温度和压强小于1 GPa情形流体氮的实验数据，所得到的势能参数被用于预测高温高密度情形氮流体的压强，预测结果证实，该解析状态方程可以很好地适用于较宽的压强和温度范围。

Analytic Equation of State for Generalized Morse Potential Fluid and Application to N2 Fluid

The analytic expressions for equation of state (EOS) and thermodynamic properties have been derived for the generalized Morse (GM) potential fluids,by using the Ross variational perturbation theory and the analytic Percus-Yevick (PY) expression of radial distribution function of hard spheres.Extensive comparison of the numerical results with computer simulations shows that the precision of the analytic Ross theory is equivalent to or slightly better than the non-analytic modified Weeks-Chandler-Anderson (mWCA) theory,and is much better than the complicated optimized reference hyper-netted chain (RHNC) theory.This analytic expressions for equation of state have been applied to N2 fluid at ambient temperature and low pressure (below 1GPa) with the parameters of the generalized Morse potential are obtained by fitting to experimental data,results of prediction of the pressure above 1GPa validate the analytic EOS with good agreement within a wide range of pressure and temperature.