Bak-Tang-Wiesenfeld Model in the Finite Range Random Link Lattice

TL;DR

This study investigates the Bak-Tang-Wiesenfeld (BTW) sandpile model on finite-range random link lattices, revealing scale-dependent fractal dimensions and regime changes influenced by lattice parameters, with implications for understanding self-organized criticality in complex networks.

Contribution

It introduces a numerical analysis of the BTW model on RLFRI, identifying a characteristic length scale and demonstrating how lattice parameters affect avalanche behavior and fractal dimensions.

Findings

Fractal dimension near 1.4 for small scales, similar to regular lattice.

Existence of a length scale where fractal dimension changes.

Different dynamics of unstable nodes in RLFRFI compared to regular lattices.

Abstract

We consider the BTW model in random link lattices with finite range interaction (RLFRI). The degree distribution for nodes is considered to be uniform in the interval $(0,n_0)$. We numerically calculate the exponents of the distribution functions in terms of $(n_0,R)$ in which $R$ is the range of interactions. Dijkstra radius is utilized to calculate the fractal dimension of the avalanches. Our analysis shows that there is, at least one length scale ($r_0(n_0,R)$) in which the fractal dimension is changed. We find that for the scales smaller than $r_0(n_0,R)$, which is typically one decade, the fractal dimension is nearly independent of $n_0$ and $R$ and is equal to $1.4$, i.e. close to that of the BTW in the regular lattice ($1.25$). Using this fact and other analysis, we conclude that the BTW-type behaviors are dominant for small values of $n_0$ and $R$, whereas for large values of these parameters a new regime is seen in which the exponent of distribution function of avalanche masses is nearly $1.4$. We also numerically calculate the explicit form of the \textit{number of unstable nodes} (NUN) as a time dependent process and show that for regular lattice it is (up to a normalization) proportional to a one dimensional Weiner process and for RLFRI it acquires a drift term. Using this dynamical variable it is numerically shown that we can not continuously approach the regular lattice limit by decreasing $R$.