Crossover from a Kosterlitz-Thouless phase transition to a discontinuous phase transition in two-dimensional liquid crystals.
Crossover from a Kosterlitz-Thouless phase transition to a discontinuous phase transition in two-dimensional liquid crystals.
复制标题
二维液晶中从 Kosterlitz-Thouless 相变到不连续相变的交叉。
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
R. Vink
中科院分区：
文献类型：
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作者：
R. Vink
二维液晶不支持长程向列有序，而是一种准相，在该相中，取向关联可能以代数方式衰减。从各向同性相到准相的转变可以是连续的和Kosterlitz-Thouless类型的，也可以是一级的。我们在这里报道了一个液晶模型，在该模型中，各向同性到准相的转变的性质可以通过对势能中的单个参数p来调节。对于pp(T)，它是一阶的。准确地说，在p=p(T)处，存在一个三临界点，其中除了方位关联外，位置关联也以代数方式衰减。详细分析了三临界行为，包括对p(T)的精确估计。这些结果来自广泛的蒙特卡罗模拟和有限尺寸尺度分析相结合。分析中最重要的是一种方案，该方案便于外推不一定是现场变量的参数中的模拟数据(在这种情况下，参数p)，还提供了其细节。对于不能应用标准直方图重加权的情况，该方案提供了一种简单而强大的替代方案。
Liquid crystals in two dimensions do not support long-range nematic order, but a quasinematic phase where the orientational correlations decay algebraically is possible. The transition from the isotropic to the quasinematic phase can be continuous and of the Kosterlitz-Thouless type, or it can be first order. We report here on a liquid-crystal model where the nature of the isotropic to quasinematic transition can be tuned via a single parameter p in the pair potential. For pp(t), it is first order. Precisely at p=p(t), there is a tricritical point where, in addition to the orientational correlations, also the positional correlations decay algebraically. The tricritical behavior is analyzed in detail, including an accurate estimate of p(t). The results follow from extensive Monte Carlo simulations combined with a finite-size scaling analysis. Paramount in the analysis is a scheme to facilitate the extrapolation of simulation data in parameters that are not necessarily field variables (in this case, the parameter p), the details of which are also provided. This scheme provides a simple and powerful alternative for situations where standard histogram reweighting cannot be applied.