摘要翻译：
人们知道，当硬球加入到纯硬棒体系中时，近晶相的稳定性可以大大提高，这种影响可以用耗尽力来解释。在本文中，我们首先研究了在这种特殊的二元系统中，取向顺序对耗尽力的影响，并将我们的结果与采用通常的考虑杆平行和它们的取向冻结的近似所得到的结果进行了比较。我们考虑了具有不同长径比的棒和不同直径的球的混合物，并在Onsager理论中处理它们。我们的结果表明，与基于冻结取向近似的相应数据相比，由于近晶相中的取向紊乱，耗尽效应和近晶稳定性显著降低。这些结果用$\tau$参数进行了讨论，该参数被提出来作为耗尽强度的一个方便的度量。我们给出了$\tau$的封闭表达式，并表明它与耗尽势密切相关。然后通过比较不同形状（球形、圆柱形和平行六面体）的平行杆系统的结果，分析了粒子几何的影响。最后，我们给出了应用于不同尺寸的平行六面体和立方体混合物的基本--测度密度--泛函理论的Zwanzig近似的结果。在这种情况下，我们证明了$\tau$参数在硬杆长宽比的大值范围内表现出线性渐近性，符合Onsager理论；在杆宽与立方体边长之比的大值范围内表现出线性渐近性，而与Onsager近似相比，$\tau$参数在预测$\tau\sim d^3$则表现出线性渐近性。
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英文标题：
《Depletion effects in smectic phases of hard rod--hard sphere mixtures》
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作者：
Yuri Martinez-Raton, Giorgio Cinacchi, Enrique Velasco, Luis Mederos
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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：
  It is known that when hard spheres are added to a pure system of hard rods the stability of the smectic phase may be greatly enhanced, and that this effect can be rationalised in terms of depletion forces. In the present paper we first study the effect of orientational order on depletion forces in this particular binary system, comparing our results with those obtained adopting the usual approximation of considering the rods parallel and their orientations frozen. We consider mixtures with rods of different aspect ratios and spheres of different diameters, and we treat them within Onsager theory. Our results indicate that depletion effects, and consequently smectic stability, decrease significantly as a result of orientational disorder in the smectic phase when compared with corresponding data based on the frozen--orientation approximation. These results are discussed in terms of the $\tau$ parameter, which has been proposed as a convenient measure of depletion strength. We present closed expressions for $\tau$, and show that it is intimately connected with the depletion potential. We then analyse the effect of particle geometry by comparing results pertaining to systems of parallel rods of different shapes (spherocylinders, cylinders and parallelepipeds). We finally provide results based on the Zwanzig approximation of a Fundamental--Measure density--functional theory applied to mixtures of parallelepipeds and cubes of different sizes. In this case, we show that the $\tau$ parameter exhibits a linear asymptotic behaviour in the limit of large values of the hard--rod aspect ratio, in conformity with Onsager theory, as well as in the limit of large values of the ratio of rod breadth to cube side length, $d$, in contrast to Onsager approximation, which predicts $\tau\sim d^3$.
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PDF链接：
https://arxiv.org/pdf/704.114