Dynamics of chain closure: Approximate treatment of nonlocal interactions
Dynamics of chain closure: Approximate treatment of nonlocal interactions
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DOI：
10.1063/1.1637574
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发表时间：
2004-02-01
影响因子：
4.4
通讯作者：
Cherayil, BJ
中科院分区：
文献类型：
--
作者：
Debnath, P;Cherayil, BJ
扩散控制反应的 Wilemski-Fixman 模型 [J.化学。物理。 58, 4009 (1973)] 与链构象的广义随机游走描述相结合，以预测闭合时间 tau 对具有反应性端基和非局部相互作用的聚合物链长 N 的依赖性。非局域相互作用是通过对聚合物的爱德华兹连续体表示中的连接项进行修改来建模的。该修饰涉及介于 0 和 1 之间的参数 h，它是链主链上相邻单体之间相关程度的度量。 h 的不同选择对应于不同平均径向尺寸的链构象。特别是，值 1/3、1/2 和 3/5 分别提供了聚合物在不良溶剂、θ 溶剂和良好溶剂中的统计数据的近似值。此类链的闭合时间 tau 是针对不同的 N 进行分析计算的。在所有情况下，发现 tau 在 N、N-b 中按幂律变化，其中 b 是 h 的函数。对于模拟塌缩聚合物和球状蛋白质的特殊情况 h=1/3，b 约为 1.6-1.7。 (C) 2004 年美国物理研究所。
The Wilemski-Fixman model of diffusion controlled-reactions [J. Chem. Phys. 58, 4009 (1973)] is combined with a generalized random walk description of chain conformations to predict the dependence of the closure time tau on the chain length N of polymers with reactive end groups and nonlocal interactions. The nonlocal interactions are modeled by a modification to the connectivity term in the Edwards continuum representation of the polymer. The modification involves a parameter h lying between 0 and 1 that is a measure of the extent of correlation between adjacent monomers on the chain backbone. Different choices of h correspond to chain conformations of different average radial dimensions. In particular, the values 1/3, 1/2 and 3/5 provide approximations to the statistics of polymers in poor, theta and good solvents, respectively. The closure time tau of such chains is calculated analytically for different N. In all cases, tau is found to vary as a power law in N, N-b, with b a function of h. For the special case h=1/3, which models collapsed polymers and globular proteins, b is about 1.6-1.7. (C) 2004 American Institute of Physics.