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arXiv 2007.16132math-phcond-mat.stat-mechmath.MP
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伊辛模型级数展开式中的Bell多项式

Bell polynomials in the series expansions of the Ising model

Grzegorz Siudem, Agata Fronczak

摘要:

通过将Bell多项式应用于三角晶格和六角晶格的伊辛模型的自由能的积分表示,我们得到了在给定能量下自旋组态数的精确组合公式(即配分函数的低温级数展开,或者,态数)。我们还将这种方法推广到更广泛的类(棋盘格)Utiyama图。除了所给出的精确公式外,我们的方法还可以在低温膨胀系数为正的晶格(如正方晶格、六方晶格)上建立团簇理想气体与伊辛模型之间的对应关系。然而,情况并非总是如此-我们提出,三角形晶格的系数可能是负的,完美的气体的集群解释是有问题的。

英文摘要:

Through applying Bell polynomials to the integral representation of the free energy of the Ising model for the triangular and hexagonal lattices we obtain the exact combinatorial formulas for the number of spin configurations at a given energy (i.e. low-temperature series expansion of the partition function or, alternatively, the number of states). We also generalize this approach to the wider class of the (chequered) Utiyama graphs. Apart from the presented exact formulas, our technique allows one to establish the correspondence between the perfect gas of clusters and the Ising model on the lattices which have positive coefficients in the low-temperature expansion (e.g. square lattice, hexagonal lattice). However it is not always the case -- we present that for the triangular lattice the coefficients could be negative and the perfect gas of clusters interpretation is problematic.

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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