Phase behavior of a binary fluid mixture of quadrupolar molecules
Phase behavior of a binary fluid mixture of quadrupolar molecules
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四极分子二元流体混合物的相行为
DOI：
10.1103/physreve.94.052601
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
H. Fukumura
中科院分区：
文献类型：
--
作者：
M. Toda;S. Kajimoto;S. Toyouchi;T. Kawakatsu;Y. Akama;M. Kotani;H. Fukumura
我们提出了一种模型分子来研究具有闭环共存区域的二元混合物的微观特性。该分子由伦纳德-琼斯粒子和单轴四极杆组成。吉布斯系综蒙特卡罗模拟表明，四极子大小相同但符号相反的高密度二元流体可以表现出闭环不混溶性。我们发现四极子大小的增加导致共存区域的缩小。分子动力学模拟还表明，在共存区域上方和下方的稳定一相区域中形成了两种类型分子交替排列的聚集体。在下临界溶解温度以下，弦结构占主导地位，而在上临界溶解温度以上，则观察到支化聚集体。我们得出的结论是，相反符号的四极子之间的各向异性相互作用在控制相行为的这些特性中起着至关重要的作用。
We propose a model molecule to investigate microscopic properties of a binary mixture with a closed-loop coexistence region. The molecule is comprised of a Lennard-Jones particle and a uniaxial quadrupole. Gibbs ensemble Monte Carlo simulations demonstrate that the high-density binary fluid of the molecules with the quadrupoles of the same magnitude but of the opposite signs can show closed-loop immiscibility. We find that an increase in the magnitude of the quadrupoles causes a shrinkage of the coexistence region. Molecular dynamics simulations also reveal that aggregates with two types of molecules arranged alternatively are formed in the stable one-phase region both above and below the coexistence region. String structures are dominant below the lower critical solution temperature, while branched aggregates are observed above the upper critical solution temperature. We conclude that the anisotropic interaction between the quadrupoles of the opposite signs plays a crucial role in controlling these properties of the phase behavior.