Lee Jae Hwan, Kim Seung-Yeon, Lee Julian
School of Systems Biomedical Science and Department of Bioinformatics and Life Science, Soongsil University, Seoul 156-743, Korea.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jul;86(1 Pt 1):011802. doi: 10.1103/PhysRevE.86.011802. Epub 2012 Jul 24.
We study conformational transitions of a polymer on a simple-cubic lattice by calculating the zeros of the exact partition function, up to chain length 24. In the complex temperature plane, two loci of the partition function zeros are found for longer chains, suggesting the existence of both the coil-globule collapse transition and the melting-freezing transition. The locus corresponding to coil-globule transition clearly approaches the real axis as the chain length increases, and the transition temperature could be estimated by finite-size scaling. The form of the logarithmic correction to the scaling of the partition function zeros could also be obtained. The other locus does not show clear scaling behavior, but a supplementary analysis of the specific heat reveals a first-order-like pseudotransition.
我们通过计算精确配分函数的零点来研究聚合物在简单立方晶格上的构象转变，链长最长为24。在复温度平面中，对于较长的链发现了配分函数零点的两个轨迹，这表明存在线圈-球状体塌缩转变和熔化-凝固转变。随着链长增加，对应于线圈-球状体转变的轨迹明显趋近实轴，并且可以通过有限尺寸标度来估计转变温度。还可以得到配分函数零点标度的对数修正形式。另一个轨迹没有显示出明显的标度行为，但对比热的补充分析揭示了一种类似一级的赝转变。
