Maximum-entropy calculation of the end-to-end distance distribution of force-stretche chains

摘要

Using the maximum-entropy method,we calculate the end-to-end distance distribution of the force-stretched chain form the moments of the distribution,which can be obtained from the extension-force curves measured in single-molecule experiments.If one knows the force expansion of the extension through the (n-1) th prower fo a force,that is enough to calculate the n moments of the distribution.We examine the method with three force-stretched chain models:the Gaussian chain,free-joined chain,and self-avoiding chain on a two-dimensional complex chain molecules:the hairpin and secondary structure conformations.We find that the distributions of homogeneous chains of the two conformational classes are quite different:there are two independent peaks in the hairpin distribution,while only one peak is observed in the distribution of secondary structure conformations.our discussion shows that the end-to-end distance distribution,instead of extension-force curves,can reveal more important physical information.