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arXiv 0908.0885cond-mat.stat-mechcond-mat.soft
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具有相关等待时间的连续时间随机游动

Continuous time random walk with correlated waiting times

A. V. Chechkin, M. Hofmann, I. M. Sokolov

摘要:

基于连续时间随机游走(CTRW)的朗之万描述,我们考虑了CTRW的推广,其中后续跳跃之间的等待时间相关。我们讨论的情况下,指数和缓慢衰减的持续的幂律相关性之间的等待时间作为两个通用的例子,并获得相应的均方位移作为时间的函数。在指数型相关性的情况下,在短时间内的(子)扩散比没有相关性的情况下慢。在长时间内,均方位移的行为与不相关的CTRW相同。对于幂律的相关性,我们发现在任何时候,其特征在于相同的指数,这似乎是小于一个不相关的CTRW的次扩散。有趣的是,在一个非常长的幂律相关性的限制情况下,(子)扩散指数并不趋于零,但从下面的子扩散指数对应于一个短时间的行为,在指数相关性的情况下有界。

英文摘要:

Based on the Langevin description of the Continuous Time Random Walk (CTRW), we consider a generalization of CTRW in which the waiting times between the subsequent jumps are correlated. We discuss the cases of exponential and slowly decaying persistent power-law correlations between the waiting times as two generic examples and obtain the corresponding mean squared displacements as functions of time. In the case of exponential-type correlations the (sub)diffusion at short times is slower than in the absence of correlations. At long times the behavior of the mean squared displacement is the same as in uncorrelated CTRW. For power-law correlations we find subdiffusion characterized by the same exponent at all times, which appears to be smaller than the one in uncorrelated CTRW. Interestingly, in the limiting case of an extremely long power-law correlations, the (sub)diffusion exponent does not tend to zero, but is bounded from below by the subdiffusion exponent corresponding to a short time behavior in the case of exponential correlations.

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