arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1609.07979cond-mat.stat-mechcond-mat.soft
收藏

多分散粒子的构型熵存在吗?

Does the configurational entropy of polydisperse particles exist?

Misaki Ozawa, Ludovic Berthier

摘要:

典型的颗粒系统的特征在于连续尺寸的多分散性,如胶体材料,不能直接使用统计力学描述,因为基本问题可能来自颗粒的可分散性。由于在这样的系统中的混合熵是发散的热力学极限,我们表明,从标准的计算方法来表征玻璃态的构型熵估计也发散。这种推理表明,多分散材料不能经历玻璃化转变,这与实验相反。我们解释说,这一论点源于相空间中的配置和自由能最小值定义的状态之间的混淆,并提出了一个简单的方法来计算一个有限的和物理意义的配置熵在连续多分散系统。物理上,所提出的方法依赖于一个有效的描述系统作为一个$M^*$组件系统与有限的$M^*$,有限的混合和构型熵。我们展示了如何直接确定$M^*$从计算机模拟的玻璃形成模型的范围内具有不同的尺寸多分散性,其特征在于硬和软粒子间的相互作用,并通过添加剂和非添加剂的相互作用。我们的方法提供了一致的结果,在所有情况下,并证明了多分散系统的构型熵存在,是有限的,可以定量估计。

英文摘要:

Classical particle systems characterized by continuous size polydispersity, such as colloidal materials, are not straightforwardly described using statistical mechanics, since fundamental issues may arise from particle distinguishability. Because the mixing entropy in such systems is divergent in the thermodynamic limit we show that the configurational entropy estimated from standard computational approaches to characterize glassy states also diverges. This reasoning would suggest that polydisperse materials cannot undergo a glass transition, in contradiction to experiments. We explain that this argument stems from the confusion between configurations in phase space and states defined by free energy minima, and propose a simple method to compute a finite and physically meaningful configurational entropy in continuously polydisperse systems. Physically, the proposed approach relies on an effective description of the system as an $M^*$-component system with a finite $M^*$, for which finite mixing and configurational entropies are obtained. We show how to directly determine $M^*$ from computer simulations in a range of glass-forming models with different size polydispersities, characterized by hard and soft interparticle interactions, and by additive and non-additive interactions. Our approach provides consistent results in all cases and demonstrates that the configurational entropy of polydisperse system exists, is finite, and can be quantitatively estimated.

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。

↑