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arXiv 0905.1224cond-mat.soft
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软排斥颗粒流体的零温phase diagram

The zero-temperature phase diagram of soft-repulsive particle fluids

Santi Prestipino, Franz Saija, Gianpietro Malescio

摘要:

与软排斥组分的有效对相互作用是聚合物溶液和胶体悬浮液的一个众所周知的特征,但它们也提供了解释简单元素的高压行为的关键。我们已经计算了零温度相图的四个不同的模型势与不同程度的核心软。在回顾的晶体结构中,也有一些非布拉维晶格,从实际系统中观察到的晶格中选择。这些晶体中的一些确实被发现对于所选择的电势是稳定的。我们认识到一个明显的普遍趋势无限的潜力,从高到低协调的晶体相,并返回后增加的压力。相反,有界排斥可能导致具有压缩的紧凑结构的间歇性出现,并且最终不会在特定相中稳定下来。在这两种情况下,流体相在中间压力下反复重新进入,正如固体的细胞理论处理所建议的那样。这些发现是相关的软物质一般,但他们也提供了新的见解的机制,对固体多晶型元素物质。

英文摘要:

Effective pair interactions with a soft-repulsive component are a well-known feature of polymer solutions and colloidal suspensions, but they also provide a key to interpret the high-pressure behaviour of simple elements. We have computed the zero-temperature phase diagram of four different model potentials with various degrees of core softness. Among the reviewed crystal structures, there are also a number of non-Bravais lattices, chosen among those observed in real systems. Some of these crystals are indeed found to be stable for the selected potentials. We recognize an apparently universal trend for unbounded potentials, going from high- to low-coordinated crystal phases and back upon increasing the pressure. Conversely, a bounded repulsion may lead to intermittent appearance of compact structures with compression and no eventual settling down in a specific phase. In both cases, the fluid phase repeatedly reenters at intermediate pressures, as suggested by a cell-theory treatment of the solids. These findings are of relevance for soft matter in general, but they also offer fresh insight into the mechanisms subtended to solid polymorphism in elemental substances.

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