arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0710.5684cond-mat.softcond-mat.mtrl-sci
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为什么Rouse模型在Polymer分子质量M<M_c时至少能令人满意地工作?

Why Does the Rouse Model Works at Least Satisfactorily at Polymer Molecular Masses M<M_c ?

Nail Fatkullin

摘要:

推广的劳斯模型,而不使用任何关于高斯分布的连接段的两端的向量的假设。在初始(一般来说,非线性)朗之万方程中,大分子连续片段的自平均自然定义了标记链的线性项,该项与经典劳斯模型的熵项仅在数值系数上不同。在无惯性近似下,简正模的关联函数的初始衰减率由Rouse模型描述,与Kuhn段两端连接矢量的涨落性质无关。如果初始朗之万方程是用动力学自洽近似来处理的,那么这种说法在任何时刻都是有效的。用布朗动力学方法对Fraenkel链的模拟表明,对于给定的链模型,线性化方程能很好地描述短波简正模自相关函数的衰减,而Rouse方程则可用于长波模。这项研究的结果使得有可能解释的库恩和劳斯段的长度,估计从静态和动态实验之间的显着差异。

英文摘要:

Generalization of the Rouse model without any use of the postulates concerning the Gaussian distribution of the vector connecting the ends of segments is advanced. In the initial (in general, nonlinear) Langevin equations, self-averaging over continuous fragments of a macromolecule naturally defines a linear term for the tagged chain, and this term differs from the entropy term of the classical Rouse model only by the numerical coefficient. According to the inertia-free approximation, the initial decay rates of correlation functions for the normal modes are described by the Rouse model independently of the character of fluctuations of the vector connecting the ends of the Kuhn segment. This statement is valid for any moment if the initial Langevin equations are treated in terms of the approximation of dynamic self-consistency. Simulation of the Fraenkel chains by the method of Brownian dynamics shows that decay of autocorrelation functions of shortwave normal modes is fairly described by the linearized equations for a given model of a chain and that the Rouse equation can be used for the longwave modes. The results of this study make it possible to explain a marked difference between the lengths of the Kuhn and Rouse segments that is estimated from static and dynamic experiments.

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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