分子的“双阱模型”位能函数及其在第二维里系数计算中之应用

THE POTENTIAL FUNCTION FOR DOUBLE SQUARE-WELL MODEL AND ITS APPLICATION TO CALCULATION OF THE SECOND VIRIAL COEFFICIENT

一、前言 欲从理论上建立描述气体热物理行为的方程,如状态方程、能量方程以及粘度方程等,首先需知道分子间相互作用位能函数,然后通过统计力学或动力学方法导出相应的模型方程,但这一数学处理过程不仅难度大,而且即使导出结果,其方程形式往往很复杂而不便于工程应用。正因为如此,Pfigogine学派提出了著名的方阱模型位能函数,它将分子看成直径为σ并有吸引力的硬球,但吸引力仅在分子间距从σ到Rσ间起作用。(R—

In the present paper, the mechanism of molecular aggregation and the character of potential function for the square-well model have b en investigated with the principle of molecular thermodynamics leading to the potential function for double square-well (DSW) model. In addition, the equation of second virial coefficient for DSW model is derived by the statistical mechanic method. The above equation obtained has been tested and the test results are excellent. It shows that this equation can well represent the behaviour of molecules for fluids.