标题： 柔性活性粒子链如何膨胀？ 显示英文标题

标题： How does a flexible chain of active particles swell?

摘要： 我们通过分析理论和计算机模拟研究由活性粒子组成的柔性线性链的膨胀。 考虑了三种不同的情况：自由链、被限制在外部谐波势中的链以及在一端被拖动的链。 首先，我们考虑一个理想链，其中具有谐波弹簧且单体之间没有排斥体积。 聚合物的Rouse模型被推广到自推进单体的情况，并进行了解析求解。 如链的空间扩展所表征的膨胀，与定义Flory指数$\nu$的单体数目成比例，该指数在三种不同情况下为$\nu =1/2, 0, 1$。 结果表明，活性不会改变Flory指数，但会影响标度定律的前因子。 这可以通过将系统映射到具有更高有效温度的平衡链来定量理解，这样链在自推进强度增加时会膨胀。 然后我们使用计算机模拟研究自避对活性聚合物膨胀的影响。 在三种不同的情况下，Flory指数现在为$\nu = 3/4, 1/4, 1$，并且在自推进下仍然不变。 然而，链的扩展在自推进强度上表现出非单调行为。 显示英文摘要

摘要： We study the swelling of a flexible linear chain composed of active particles by analytical theory and computer simulation. Three different situations are considered: a free chain, a chain confined to an external harmonic trap, and a chain dragged at one end. First we consider an ideal chain with harmonic springs and no excluded volume between the monomers. The Rouse model of polymers is generalized to the case of self-propelled monomers and solved analytically. The swelling, as characterized by the spatial extension of the chain, scales with the monomer number defining a Flory exponent $\nu$ which is $\nu =1/2, 0, 1$ in the three different situations. As a result, we find that activity does not change the Flory exponent but affects the prefactor of the scaling law. This can be quantitatively understood by mapping the system onto an equilibrium chain with a higher effective temperature such that the chain swells under an increase of the self-propulsion strength. We then use computer simulations to study the effect of self-avoidance on active polymer swelling. In the three different situations, the Flory exponent is now $\nu = 3/4, 1/4, 1$ and again unchanged under self-propulsion. However, the chain extension behaves non-monotonic in the self-propulsion strength.