2D聚合物逃逸跃迁的顺序是什么？
What is the order of 2D polymer escape transition?
摘要：
在两个活塞之间的三维空间中，当链中的单体数目N达到临界值时，末端接枝的柔性聚合物链经历从受限卷曲到花状构象的突然转变。在2D几何中，限制在有限长度2L的条带内的链的单体之间的排除体积相互作用将卷曲构象转换成线性串的斑点。然而，斑点图像提出了关于这种逃逸跃迁的性质的问题。为了检查的理论预测的基础上的斑点图片，我们研究了2d单聚合物链排除体积相互作用和一端接枝在中间的一条长度为2L和宽度为H的模拟自我避免行走的方形晶格上的修剪丰富Rosenbluth方法（PERM）。我们估计的自由能，末端到末端的距离，囚禁的单体的数量，序参量，和它的分布。结果表明，在大N和L但有限L/N的热力学极限下，包括序参量在内的几个平均特征存在一个小但有限的跳跃。我们还提出了一个理论描述的基础上的朗道自由能方法，这是在很好的协议与模拟结果。模拟结果和解析理论都表明，二维逃逸相变是一个弱的一级相变。
英文摘要：
An end-grafted flexible polymer chain in 3d space between two pistons undergoes an abrupt transition from a confined coil to a flower-like conformation when the number of monomers in the chain, N, reaches a critical value. In 2d geometry, excluded volume interactions between monomers of a chain confined inside a strip of finite length 2L transform the coil conformation into a linear string of blobs. However, the blob picture raises questions on the nature of this escape transition. To check the theoretical predictions based on the blob picture we study 2d single polymer chains with excluded volume interactions and with one end grafted in the middle of a strip of length 2L and width H by simulating self-avoiding walks on a square lattice with the pruned-enriched-Rosenbluth method (PERM). We estimate the free energy, the end-to-end distance, the number of imprisoned monomers, the order parameter, and its distribution. It is shown that in the thermodynamic limit of large N and L but finite L/N, there is a small but finite jump in several average characteristics, including the order parameter. We also present a theoretical description based on the Landau free energy approach, which is in good agreement with the simulation results. Both simulation results and the analytical theory indicate that the 2d escape transition is a weak first-order phase transition.
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。
