链状分子状态方程的推导及热容的推算

在Barker Henderson, Zhang以及Wertheim 等微扰理论的基础上,以方阱势硬球流体为参考体系,将Zhang的解析表达方法与Wertheim 的链成键自由能的处理方法结合起来,推导出自由链接的链状分子流体的Helmholtz自由能的解析表达式,并得到了压缩因子、内能、恒容热容等热力学性质的计算式.计算结果与MC(Monte Carlo)模拟结果吻合良好.对Zhang的解析表达式与“TPT D”(二阶Wertheim微扰理论)的结合也作了推导和计算.

New Perturbation Theory Model for Chain- like Molecule Fluid and the Predicted Heat Capacity

A model for the freely jointed square well chain fluid is developed based on the thermodynamic perturbation theory of Barker Henderson,Zhang and Wertheim.The analytic representations of square well monomer by Zhang are extended to obtain a series of representations for thermodynamic properties of square well chain fluids using the incorporating structural information for square well monomer of Wertheim's TPT1 model.The same work has been done using incorporating structural information for the diatomic square well fluid of TPT D model.The calculated results of compressibility factor,residual internal energy and constant volume heat capacity of 4 mer,8 mer and 16 mer chain fluids are tested against the MC results and a careful comparison between the model from TPT1 and that from TPT D has been made.The former agree with MC results much better than the later,especially for internal energy.To obtain the constant volume heat capacity,NVT MC simulations have been performed.