arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0812.4139cond-mat.str-elcond-mat.stat-mech
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自旋系统的关联集团平均场论理论

Correlated cluster mean-field theory for spin systems

Daisuke Yamamoto

摘要:

介绍了一种团簇平均场方法,并给出了它在伊辛模型和海森堡模型中的应用。我们把晶格网站成簇的大小和形状的选择,使集群中的所有网站的等价性被保存。由于集群与周围集群的相互作用的强度强烈依赖于中心集群本身的自旋配置,我们包括在有效场作用于自旋的贡献。集群之间的“相关性”的影响可以考虑超出标准的平均场水平,因此,我们的集群为基础的方法给出了定性(甚至定量)正确的结果伊辛和海森堡模型。特别是对于蜂窝和正方形格子上的伊辛模型,其临界温度的计算结果与精确值非常接近(仅高估不到5%)。

英文摘要:

A cluster mean-field method is introduced and the applications to the Ising and Heisenberg models are demonstrated. We divide the lattice sites into clusters whose size and shape are selected so that the equivalence of all sites in a cluster is preserved. Since the strength of interactions of a cluster with its surrounding clusters is strongly dependent on the spin configuration of the central cluster itself, we include this contribution in the effective fields acting on the spins. The effects of "correlations" between clusters can be taken into account beyond the standard mean-field level, and as a result our cluster-based method gives qualitatively (and even quantitatively) correct results for the both Ising and Heisenberg models. Especially, for the Ising model on the honeycomb and square lattices, the calculated results of the critical temperature are very close (overestimated by only less than 5 %) to the exact values.

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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