Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada.
J Chem Phys. 2010 May 7;132(17):174102. doi: 10.1063/1.3417385.
The conformation of an ideal polymer chain confined in a box with a D x D hole is studied by N-step random walk simulations. For a polymer chain tethered inside the box, three conformational states are observed when the chain length is increased. For short chains the polymer assumes "mushroom" configurations. Increasing the chain length leads to a state in which the polymer fills the box. When the chain is long enough, the polymer escapes from the box, assuring an overall random walk state. Probability distributions of the free end and end-to-end distance are used to characterize polymer conformations. The escape transition is determined by the disappearance of the bimodal feature in the end-to-end probability density function. A crossover of the free energy difference between the confined and escaped states signals an escape transition analogous to the coil-globule transition of a free ideal chain.
通过 N 步随机行走模拟研究了理想聚合物链在具有 D x D 孔的盒子中的构象。对于束缚在盒子内部的聚合物链，当链长增加时，观察到三种构象状态。对于短链，聚合物呈现“蘑菇”构型。增加链长会导致聚合物填充盒子的状态。当链足够长时，聚合物会从盒子中逃脱，确保整体随机行走状态。自由端和末端到末端距离的概率分布用于表征聚合物构象。通过末端到末端概率密度函数的双峰特征的消失来确定逃逸转变。受限和逃逸状态之间的自由能差的交叉表明了类似于自由理想链的无规卷曲-球粒转变的逃逸转变。
