摘要
本工作提出了一种新的直接用Monte Carlo模拟方法计算聚合物链构象熵,我们称这种方法为构象计数法。在本文中首先叙述了这个方法的计算原理,然后将它应用到简单立方格子中的无规自避行走问题上。具体计算了短链(链步数n=7～19)和长链(n～2100)时的熵在短链下所得到的熵数据与准确值相比偏差在0.04％以内(2000个样本)。在长链下所得到的熵数据与重整化群理论的结果相比,误差在0.8％左右(样本数为300)。同时本文还计论了限制在边长为2的立方体内,最大链步数n=26的受限链的构象熵。由本方法所求得的数据和用直接计算构象数得到的熵准确值也符合得很好。偏差在0.6％以内(2000个样本)。本文还对权重因子进行了讨论,提出改进数据准确度的方法。
In this paper a new approximate method, which is called 'The Conformational Counting Method', for estimating the Conformational entropy of polymer chains has been proposed. The method is applied to random self-avoiding walks on simple cubic lattice. In the range of chain step number n= 7~19 the entropy data obtained by this method are consistent perfectly with their precise value and the deviation is smaller than 0.04% (sample sizes- 2,000). In the range of n up to 26 of chains confined in a cubic box of side length 2 the entropy data are consistent very good also with their precise value obtained by means of directly counting all conformations. The deviation is smaller than 0.6% (sample sizes ~2,000). In the range of n up to 2,100 of free chains, the entropy -data confirm the renormalization group prediction:where k is Boltzmann constant,u = 4.6838, r = 7/6 and C0 = 1.17. For all chain step number deviations are negative and within 0.8%(sample sizes~ 300). The way to improve the accuracy is suggested.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
1989年第3期310-315,共6页
Acta Polymerica Sinica
关键词
聚合物
构象熵
单链
构象计数法
The chain of random self-avoiding walks, Conformational entropy,Rosenbluth-Rosenbluth weighting factor, Conformational counting method
