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arXiv 1111.4323cond-mat.stat-mechcond-mat.soft
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分数布朗运动与拉链聚合物的临界动力学

Fractional Brownian motion and the critical dynamics of zipping polymers

Jean-Charles Walter, Alessandro Ferrantini, Enrico Carlon, Carlo Vanderzande

摘要:

我们考虑两个长度为$L$的互补聚合物链通过共同的末端单体连接。两条链通过互补单体结合,在低温下形成双链构象(拉链),而在高温下它们解离(解拉链)。这是DNA(或RNA)发夹形成的简单模型。在这里,我们调查的动态链在平衡临界温度$T=T_c$使用Monte Carlo劳斯动力学。我们发现,动力学是异常的,与$τ\sim L^{2.26(2)}$的特征时间标度,超过了劳斯时间$\sim L^{2.18}$。我们调查的概率分布函数,速度自相关函数,生存概率和边界行为的基本随机过程。这些量的比例与Hurst指数为$H=0.44(1)$的分数布朗运动的比例相同。我们讨论了无偏聚合物易位的相似性和差异。

英文摘要:

We consider two complementary polymer strands of length $L$ attached by a common end monomer. The two strands bind through complementary monomers and at low temperatures form a double stranded conformation (zipping), while at high temperature they dissociate (unzipping). This is a simple model of DNA (or RNA) hairpin formation. Here we investigate the dynamics of the strands at the equilibrium critical temperature $T=T_c$ using Monte Carlo Rouse dynamics. We find that the dynamics is anomalous, with a characteristic time scaling as $τ\sim L^{2.26(2)}$, exceeding the Rouse time $\sim L^{2.18}$. We investigate the probability distribution function, the velocity autocorrelation function, the survival probability and boundary behaviour of the underlying stochastic process. These quantities scale as expected from a fractional Brownian motion with a Hurst exponent $H=0.44(1)$. We discuss similarities and differences with unbiased polymer translocation.

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