摘要翻译：
本文利用具有旋转自由度的二维硬粒子二元混合物的标度粒子理论，分析了各种混合物的向列相的稳定性和分相行为，重点讨论了至少有一个组分由硬矩形或硬正方形组成的情况。硬矩形的纯流体除了通常的单轴向列相外，还可以表现出具有两个指向矢的附加（四）取向相，这类似于三维流体中的双轴或立体相。计算机模拟表明，对于低长宽比的矩形，四元相相对于空间有序相可能是稳定的。当硬矩形与其它本身不具有稳定四元相的粒子混合时，四元相通过一级或二级相变失稳为单轴向列相或各向同性相；对于低长宽比的硬矩形，在相对较大的体积分数范围内存在四次有序。这些转变的顺序取决于混合物的粒子几何形状、尺寸和热力学条件。混合物的第二个成分被选择为硬盘或迪斯科矩形，其几何形状不同于矩形，导致包装挫折和分离行为，或者只是不同长宽比的矩形。这些混合物可能是观察硬质粒子单层中热力学稳定的四相的良好候选者。最后，当尺寸比足够大时，流体（各向同性--四相或四相--四相）相在不同尺寸的硬方块混合物中发生解离。
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英文标题：
《Demixing and orientational ordering in mixtures of rectangular particles》
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作者：
D. de las Heras, Y. Martinez-Raton and E. Velasco
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Soft Condensed Matter        软凝聚态物质
分类描述：Membranes, polymers, liquid crystals, glasses, colloids, granular matter
膜，聚合物，液晶，玻璃，胶体，颗粒物质
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一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  Using scaled-particle theory for binary mixtures of two-dimensional hard particles with rotational freedom, we analyse the stability of nematic phases and the demixing phase behaviour of a variety of mixtures, focussing on cases where at least one of the components consists of hard rectangles or hard squares. A pure fluid of hard rectangles may exhibit, aside from the usual uniaxial nematic phase, an additional (tetratic) oriented phase, possessing two directors, which is the analogue of the biaxial or cubatic phases in three- dimensional fluids. There is computer simulation evidence that the tetratic phase might be stable with respect to phases with spatial order for rectangles with low aspect ratios. As hard rectangles are mixed with other particles not possessing stable tetratic order by themselves, the tetratic phase is destabilised, via a first- or second-order phase transition, to uniaxial nematic or isotropic phases; for hard rectangles of low aspect ratio tetratic order persists in a relatively large range of volume fractions. The order of these transitions depends on the particle geometry, dimensions and thermodynamic conditions of the mixture. The second component of the mixture has been chosen to be hard discs or disco-rectangles, the geometry of which is different from that of rectangles, leading to packing frustration and demixing behaviour, or simply rectangles of different aspect ratio. These mixtures may be good candidates for observing thermodynamically stable tetratic phases in monolayers of hard particles. Finally, demixing between fluid (isotropic--tetratic or tetratic--tetratic) phases is seen to occur in mixtures of hard squares of different sizes when the size ratio is sufficiently large.
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PDF链接：
https://arxiv.org/pdf/705.0868