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应用Yethiraj的加权密度近似泛函理论研究平板狭缝中方阱链流体的密度分布,系统的Helmholtz自由能泛函分为理想气体的贡献利剩余贡献两部分,其中剩余贡献部分分别采用刘洪来等人建立的基于空穴相关函数的方阱链流体状态方程和Gil_Villegas等人提出的统计缔合流体理论状态方程(SAFT_VR)结合简单加权密度近似计算.考察了不同链长、温度、系统密度和壁面吸引强度下平板狭缝中方阱链流体的密度分布,并与MonteCarlo(MC)模拟结果进行了比较.结果表明采用不同的状态方程对密度分布的计算有明显的影响,对于受限于硬壁狭缝中的方阱链流体,温度和密度比较高时,两种状态方程计算的结果均与MC模拟符合得比较好,在低温和低密度下效果变差,SAFT_VR方程的计算结果更接近于MC模拟结果.对于受限于方阱壁狭缝中的方阱链流体,由于系统密度分布的非均匀性加强,采用两种状态方程计算的结果均与MC模拟结果有一定偏差,寻找更合适的权重函数是进一步改进的关键.
The Density Density approximation functional theory of Yethiraj is used to study the density distribution of the square-well chain flow in the flat-plate slit. The Helmholtz free energy functional of the system is divided into two parts: the contribution of the ideal gas and the remaining contribution. The remaining contributions are established by Liu et al. Based on the hole correlation function of the square-well chain fluid equation of state and Gil_Villegas et al proposed statistical association fluid theory equation of state (SAFT_VR) combined with simple weighted density approximation calculation.Examine the different chain length, temperature, system density and wall suction intensity And the results of Monte Carlo (MC) simulation are compared.The results show that the different state equations have a significant influence on the density distribution calculation, and for the limited distribution in the hard-wall slits , The calculated results of the two state equations are in good agreement with the MC simulation and the results are worse at low temperature and low density. The calculation results of the SAFT_VR equation are closer to those of the MC simulation . For square-well chain fluids that are confined to the square-well wall slits, due to the non-uniformities in the density distribution of the system, two The results of state equation calculation have some deviations from MC simulation results. Finding a more suitable weighting function is the key to further improvement.