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arXiv 1503.09028cond-mat.stat-mech
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连续时间随机游动和猝灭能量景观中的老化首次通过时间密度

Ageing first passage time density in continuous time random walks and quenched energy landscapes

Henning Krusemann, Aljaz Godec, Ralf Metzler

摘要:

在连续时间随机游走(CTRW)框架下,研究了老龄化随机过程的首次穿越动力学。在这样的CTRW过程中,测试粒子执行随机游走,其中连续的步骤由根据等待时间概率密度函数($ψ(t) \simeq t^{-1-α}$)($0\le α\le 2$)分布的随机等待时间分开。一个老化随机过程是由其动态量对老化时间$t_a$的显式依赖性定义的,老化时间是从准备到开始观察之间所经过的时间。亚扩散老化CTRW描述了诸如非晶半导体中的载流子、地质和生物系统中的示踪剂分散或闪烁量子点的动力学等系统。我们推导出的精确形式的第一次通过时间密度的老化subdiffusively CTRW在半无限的,封闭的,有偏见的情况下,发现不同的标度制度弱,中等,和强老化系统:这些制度,具有不同的标度律,也发现当标度指数是在范围$1<α<2$,足够长的$t_a$。我们比较我们的结果与老化运动的测试粒子在淬火的能量景观。我们测试我们的理论结果在淬火景观对模拟:只有当偏见是足够强,从返回到以前访问过的网站的相关性变得微不足道,结果接近老化CTRW的结果。在小偏差或无偏差的情况下,老化效应消失,并且可以发现与完全退火景观的情况相比指数的变化,反映了淬火景观中相关性的建立。

英文摘要:

We study the first passage dynamics of an ageing stochastic process in the continuous time random walk (CTRW) framework. In such CTRW processes the test particle performs a random walk, in which successive steps are separated by random waiting times distributed in terms of the waiting time probability density function $ψ(t) \simeq t^{-1-α}$) ($0\le α\le 2$). An ageing stochastic process is defined by the explicit dependence of its dynamic quantities on the ageing time $t_a$, the time elapsed between its preparation and the start of the observation. Subdiffusive ageing CTRWs describe systems such as charge carriers in amorphous semiconductors, tracer dispersion in geological and biological systems, or the dynamics of blinking quantum dots. We derive the exact forms of the first passage time density for an ageing subdiffusive CTRW in the semi-infinite, confined, and biased case, finding different scaling regimes for weakly, intermediately, and strongly aged systems: these regimes, with different scaling laws, are also found when the scaling exponent is in the range $1<α<2$, for sufficiently long $t_a$. We compare our results with the ageing motion of a test particle in a quenched energy landscape. We test our theoretical results in the quenched landscape against simulations: only when the bias is strong enough, the correlations from returning to previously visited sites become insignificant and the results approach the aging CTRW results. With small or without bias, the ageing effects disappear and a change in the exponent compared to the case of a completely annealed landscape can be found, reflecting the build-up of correlations in the quenched landscape.

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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