Singh Ram C, Ram Jokhan, Singh Yashwant
Department of Physics, Banaras Hindu University, Varanasi 221 005, India.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 1):031711. doi: 10.1103/PhysRevE.65.031711. Epub 2002 Feb 19.
We have calculated the pair-correlation functions of a fluid interacting via the Gay-Berne (n-6) pair potentials using the Percus-Yevick integral equation theory and have shown how these correlations depend on the value of n that measures the sharpness of the repulsive core of the pair potential. These results have been used in the density-functional theory to locate the freezing transitions of these fluids. We have used two different versions of the theory known as the second order and the modified weighted-density-functional theory and examined the freezing of these fluids for 8< or =n< or =30 and in the reduced temperature range lying between 0.65 and 1.25 into the nematic and the smectic A phases. For none of these cases smectic A phase was found to be stabilized though in some range of temperature for a given n it appeared as a metastable state. We have examined the variation of freezing parameters for the isotropic-nematic transition with temperature and n. We have also compared our results with simulation results wherever they are available. While we find that the density-functional theory is good to study the freezing transitions in such fluids the structural parameters found from the Percus-Yevick theory need to be improved particularly at high temperatures and lower values of n.
我们使用珀西-耶维克积分方程理论计算了通过盖伊-伯恩（n - 6）对势相互作用的流体的对关联函数，并展示了这些关联如何依赖于衡量对势排斥核锐度的n值。这些结果已被用于密度泛函理论中以确定这些流体的冻结转变。我们使用了该理论的两个不同版本，即二阶理论和修正加权密度泛函理论，并研究了在8≤n≤30以及0.65至1.25的约化温度范围内这些流体向向列相和近晶A相的冻结情况。在所有这些情况下，均未发现近晶A相是稳定的，尽管在给定n的某些温度范围内它表现为亚稳态。我们研究了各向同性-向列转变的冻结参数随温度和n的变化。只要有模拟结果，我们也将我们的结果与之进行了比较。虽然我们发现密度泛函理论对于研究此类流体的冻结转变是有效的，但从珀西-耶维克理论得到的结构参数需要改进，特别是在高温和较低n值的情况下。
