论文标题

相关函数和在精确分区函数的硬盘的准硬盘系统中的订购

Correlation functions and ordering in a quasi-one dimensional system of hard disks from the exact canonical partition function

论文作者

Pergamenshchik, V. M., Bryk, T. M., Trokhymchuk, A. D.

论文摘要

硬盘的准尺寸(Q1D)系统的分析规范NLT分区函数[J.化学物理。 V.153,144111(2020)]对该系统(孔)中的热力学和顺序进行了直接分析描述,作为有限和无限系统的线性密度N/L的函数。它是基于等速NPT集合的开发良好的传输矩阵方法的替代方法。我们得出了转换对分布函数(PDF)和下一个邻居磁盘之间距离的实际距离依赖性的分析公式,然后通过计算孔中的翻译顺序来证明它们的使用。在所有情况下,都认为该顺序是短范围,并且会随着磁盘的分离而成倍地衰减。 Q1D孔隙宽度和不同密度的整个范围内显示的相关长度显示出非单调依赖性,最大值在密度n/l = 1处最大,并且趋向于消失的孔宽度的1D值。结果表明,当孔长度L完全等于N磁盘直径时,该密度的特殊作用。我们引入了一个定向顺序参数,该参数说明了磁盘形成的晶体曲折的局部质量,并且与其结构元素有关。该参数在密集的状态下最大,并且消失的密度非常低。由于特定的准尺寸几何形状,该宏观阶参数参数沿孔稳定,因此宏观定向阶的液体晶体类型为液体晶体。

The analytical canonical NLT partition function of a quasi-one dimensional (q1D) system of hard disks [J. Chem Phys. v.153, 144111 (2020)] provides a direct analytical description of the thermodynamics and ordering in this system (a pore) as a function of the linear density N/L both for finite and infinite systems. It is alternative to the well-developed transfer matrix method based on the isobaric NPT ensemble. We derive the analytical formulae for the actual distance dependence of the translational pair distribution function (PDF) and the DF of distances between next neighbor disks, and then demonstrate their use by calculating the translational order in the pore. In all cases, the order is found to be of a short range and to exponentially decay with the disks' separation. The correlation length presented for the whole range of the q1D pore widths and different densities shows a non-monotonic dependence with a maximum at the density N/L=1 and tends to the 1D value for a vanishing pore width. The results indicate a special role of this density when the pore length L is equal exactly to N disk diameters. We introduce an orientational order parameter that accounts for the local quality of the crystalline zigzag formed by disks and is related to its structural element. This parameter is maximum in the densely packed state and vanishes for a very low density. Due to specific quasi-one dimensional geometry, this macroscopic order parameter is constant along the pore so that the macroscopic orientational order is of a liquid crystalline type.

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