Ingebrigtsen Trond S, Dyre Jeppe C
Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark.
J Phys Chem B. 2023 Mar 30;127(12):2837-2846. doi: 10.1021/acs.jpcb.3c00346. Epub 2023 Mar 16.
Size-polydisperse liquids have become standard models for avoiding crystallization, thereby enabling studies of supercooled liquids and glasses formed, e.g., by colloidal systems. Purely -polydisperse liquids have been studied much less, but provide an interesting alternative. We here study numerically the difference in structure and dynamics obtained by introducing these two kinds of polydispersity into systems of particles interacting via the Lennard-Jones and EXP pair potentials. To a very good approximation, the average pair structure and dynamics are unchanged even for strong energy polydispersity, which is not the case for size-polydisperse systems. When the system at extreme energy polydispersity undergoes a continuous phase separation into lower and higher particle-energy regions whose structure and dynamics are different from the average, the average structure and dynamics are still virtually the same as for the monodisperse system. Our findings are consistent with the fact that the distribution of forces on the individual particles do not change when energy polydispersity is introduced, while they do change in the case of size polydispersity. A theoretical explanation remains to be found, however.
尺寸多分散液体已成为避免结晶的标准模型，从而能够对例如由胶体系统形成的过冷液体和玻璃进行研究。纯能量多分散液体的研究要少得多，但提供了一个有趣的替代方案。我们在此通过数值研究将这两种多分散性引入通过 Lennard-Jones 和 EXP 对势相互作用的粒子系统中所获得的结构和动力学差异。在非常好的近似下，即使对于强能量多分散性，平均对结构和动力学也保持不变，而尺寸多分散系统则并非如此。当处于极端能量多分散性的系统经历连续相分离成结构和动力学与平均值不同的较低和较高粒子能量区域时，平均结构和动力学实际上仍与单分散系统相同。我们的发现与以下事实一致：引入能量多分散性时，单个粒子上的力分布不变，而在尺寸多分散性的情况下则会改变。然而，仍有待找到理论解释。
