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arXiv 0706.2162cond-mat.softcond-mat.stat-mech
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类氢相互作用和各向同性相互作用对polymer坍缩的竞争

The competition of hydrogen-like and isotropic interactions on polymer collapse

J Krawczyk, A L Owczarek, T Prellberg

摘要:

我们调查的晶格模型的聚合物,其中最近邻单体-单体相互作用强度不同,根据当地的配置是否有所谓的“类氢”的形成或没有。如果相互作用强度都相同,则在降低温度时发生经典的$θ$点塌陷转变,并且聚合物进入称为塌陷小球的各向同性液滴相。另一方面,强烈有利于类氢相互作用引起的各向异性折叠(固体状)相上降低温度。我们使用蒙特卡罗模拟的长度为256映射出的参数平面中的相图,并确定相关的相变的顺序。我们讨论了半柔性聚合物和其他聚合物模型的连接。重要的是,我们证明了,对于一系列的能量参数的两个相变发生在降低温度,第二个是从小球状态到晶体状态的过渡。我们认为,从我们的数据,这个球到晶体的过渡是连续的,在两个维度上符合场理论的参数有关哈密顿走,但在三维的第一顺序。

英文摘要:

We investigate a lattice model of polymers where the nearest-neighbour monomer-monomer interaction strengths differ according to whether the local configurations have so-called ``hydrogen-like'' formations or not. If the interaction strengths are all the same then the classical $θ$-point collapse transition occurs on lowering the temperature, and the polymer enters the isotropic liquid-drop phase known as the collapsed globule. On the other hand, strongly favouring the hydrogen-like interactions give rise to an anisotropic folded (solid-like) phase on lowering the temperature. We use Monte Carlo simulations up to a length of 256 to map out the phase diagram in the plane of parameters and determine the order of the associated phase transitions. We discuss the connections to semi-flexible polymers and other polymer models. Importantly, we demonstrate that for a range of energy parameters two phase transitions occur on lowering the temperature, the second being a transition from the globule state to the crystal state. We argue from our data that this globule-to-crystal transition is continuous in two dimensions in accord with field-theory arguments concerning Hamiltonian walks, but is first order in three dimensions.

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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