论文标题

Barabási-Albert网络的远程伊辛模型

A Long-Range Ising Model of a Barabási-Albert Network

论文作者

Krishnan, Jeyashree, Torabi, Reza, Di Napoli, Edoardo, Honerkamp, Carsten, Schuppert, Andreas

论文摘要

具有幂律连通性的网络(通常称为无标度网络)是重要类别的复杂网络类别。先前已经为Barabási-Albert网络模型的Ising模型提出了一个异质的平均近似值,该模型在节点上具有经典旋转的无尺度网络模型,其中表明此类系统的临界温度与网络大小对数进行对数。对于有限尺寸,这种系统没有关键,因此在奇异行为方面没有真正的相变。此外,在热力学极限中,即使在那时,无限临界温度的平均景观预测仍可能排除任何真实的相变。然而,考虑到该模型在通常是有限的生物系统上的潜在应用时,人们可能仍会尝试找到定量描述相关可观察物的近似值。在这里,我们提出了一种替代性,近似的公式,以描述Barabási-Albert网络的Ising模型。使用磁化的经典定义,我们表明,网络上的Ising模型可以通过长期相互作用的同质ISING模型来良好地对待,其中网络夫妇的每个节点都以Barabási-Albert网络的平均值确定的所有其他自旋。在Barabási-Albert网络的如此有效的远程ISING模型中,临界温度与为增长网络添加的优先连接链接的数量成正比。提出的模型描述了与异质平均场近似相比,平均或小于平均程度的大多数站点的磁化。远距离的ISING模型是我们所知道的Barabási-Albert网络的唯一同质描述。

Networks that have power-law connectivity, commonly referred to as the scale-free networks, are an important class of complex networks. A heterogeneous mean-field approximation has been previously proposed for the Ising model of the Barabási-Albert model of scale-free networks with classical spins on the nodes wherein it was shown that the critical temperature for such a system scales logarithmically with network size. For finite sizes, there is no criticality for such a system and hence no true phase transition in terms of singular behavior. Further, in the thermodynamic limit, the mean-field prediction of an infinite critical temperature for the system may exclude any true phase transition even then. Nevertheless, with an eye on potential applications of the model on biological systems that are generally finite, one may still try to find approximations that describe the relevant observables quantitatively. Here we present an alternative, approximate formulation for the description of the Ising model of a Barabási-Albert Network. Using the classical definition of magnetization, we show that Ising models on a network can be well-approximated by a long-range interacting homogeneous Ising model wherein each node of the network couples to all other spins with a strength determined by the mean degree of the Barabási-Albert Network. In such an effective long-range Ising model of a Barabási-Albert Network, the critical temperature is directly proportional to the number of preferentially attached links added to grow the network. The proposed model describes the magnetization of the majority of the sites with average or smaller than average degree better compared to the heterogeneous mean-field approximation. The long-range Ising model is the only homogeneous description of Barabási-Albert networks that we know of.

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