Kumar Sanjay, Jensen Iwan, Jacobsen Jesper L, Guttmann Anthony J
Department of Physics, Banaras Hindu University, Varanasi 221 005, India.
Phys Rev Lett. 2007 Mar 23;98(12):128101. doi: 10.1103/PhysRevLett.98.128101. Epub 2007 Mar 19.
A statistical mechanical description of flexible and semiflexible polymer chains in a poor solvent is developed in the constant force and constant distance ensembles. We predict the existence of many intermediate states at low temperatures stabilized by the force. A unified response to pulling and compressing forces has been obtained in the constant distance ensemble. We show the signature of a crossover length which increases linearly with the chain length. Below this crossover length, the critical force of unfolding decreases with temperature, while above, it increases with temperature. For stiff chains, we report for the first time sawtoothlike behavior in the force-extension curves which has been seen earlier in the case of protein unfolding.
在恒力和恒距系综中，建立了在不良溶剂中柔性和半柔性聚合物链的统计力学描述。我们预测在低温下存在许多由力稳定的中间态。在恒距系综中获得了对拉力和压力的统一响应。我们展示了一个交叉长度的特征，它随链长线性增加。在这个交叉长度以下，展开的临界力随温度降低，而在其之上，它随温度升高。对于刚性链，我们首次报道了力-伸长曲线中的锯齿状行为，这种行为在蛋白质展开的情况中较早被观察到。
