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arXiv 1912.04528cond-mat.stat-mech
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离散热力学系统解析几何的热带极限

Tropical Limit for Configurational Geometry in Discrete Thermodynamic Systems

Koretaka Yuge, Shouno Ohta

摘要:

对于经典的具有恒定组成的离散系统(通常指置换合金)在热力学平衡态下,宏观结构原则上应该通过玻尔兹曼因子exp(-bE)依赖于温度和多体相互作用。尽管如此,我们最近发现:(i)结构的热力学平均可以用一组特殊的微观态来表征,这些微观态的结构与能量和温度无关;(ii)微观结构与势能面之间的热力学平均的双向稳定性可以在没有任何温度或多体相互作用信息的情况下来表述。这些结果强烈表明构型几何的重要作用,其中结构自由度(ASDF)的非谐性是构型空间上的矢量场,起着核心作用,直观地对应于热力学平均的非线性仅取决于构型几何。虽然ASDF可以通过基于诸如蒙特卡罗模拟的数值模拟来实际绘制,但是仍然不清楚其整体特性如何由底层晶格的几何形状支配。我们在这里表明,通过应用热带几何中的极限(即,热带极限),通过对离散动力系统的特殊尺度变换,我们发现了单结构自由度二元系统构型几何非线性伸缩与晶格几何信息之间的热带关系。热带极限的提出,将是一个强有力的程序,以简化复杂的非线性性质的热力学平均与多个SDF系统的分析。

英文摘要:

For classical discrete systems with constant composition (typically referred to substitutional alloys) under thermodynamically equilibrium state, macroscopic structure should in principle depend on temperature and many-body interaction through Boltzmann factor, exp(-bE). Despite this fact, our recently find that (i) thermodynamic average for structure can be characterized by a set of special microscopic state whose structure is independent of energy and temperature, and (ii) bidirectional-stability character for thermodynamic average between microscopic structure and potential energy surface is formulated without any information about temperature or many-body interaction. These results strongly indicates the significant role of configurational geometry, where anharmonicity in structural degree of freedom (ASDF) that is a vector field on configuration space, plays central role, intuitively corresponding to nonlinearity in thermodynamic average depending only on configurational geometry. Although ASDF can be practically drawn by performing numerical simulation based on such as Monte Carlo simulation, it is still unclear how its entire character is dominated by geometry of underlying lattice. We here show that by applying the limit in tropical geometry (i.e., tropical limit) with special scale-transformation to discrete dynamical system for ASDF, we find tropical relationships between how nonlinearity in terms of configurational geometry expands or shrinks and geometric information about underlying lattice for binary system with a single structural degree of freedom (SDF). The proposed tropical limit will be powerful procedure to simplify analyzation of complicated nonlinear character for thermodynamic average with multiple SDF systems.

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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