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arXiv 1401.6301cond-mat.stat-mech
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二维液晶中无Kosterlitz相变到不连续相变的交叉

Crossover from a Kosterlitz-Thouless to a discontinuous phase transition in two-dimensional liquid crystals

Richard L. C. Vink

摘要:

二维液晶不支持长程有序,但可能是准有序相,其中取向关联代数衰减。从各向同性相到准共晶相的转变可以是连续的Kosterlitz-plasterless型,或者它可以是一阶的。我们在这里报告的液晶模型的各向同性准相变的性质可以通过一个单一的参数$p$在对潜在的调谐。对于$p<p_t$,跃迁是Kosterlitz-numerless型的,而对于$p>p_t$,它是一阶的。精确地说,在$p=p_t$处,有一个三临界点,在那里,除了取向相关性之外,位置相关性也代数地衰减。详细分析了三临界行为,包括对$p_t$的精确估计。结果遵循广泛的蒙特卡罗模拟结合有限尺寸标度分析。在分析中最重要的是一个方案,以方便外推的模拟数据的参数,不一定是字段变量(在这种情况下,参数$p$)的细节也提供。该方案为无法应用标准直方图重新加权的情况提供了一种简单而强大的替代方案。

英文摘要:

Liquid crystals in two dimensions do not support long-ranged nematic order, but a quasi-nematic phase where the orientational correlations decay algebraically is possible. The transition from the isotropic to the quasi-nematic phase can be continuous 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 quasi-nematic transition can be tuned via a single parameter $p$ in the pair potential. For $p<p_t$, the transition is of the Kosterlitz-Thouless type, while for $p>p_t$ 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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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