Laboratoire Charles Coulomb, UMR 5221 CNRS, Université de Montpellier, 34095 Montpellier, France.
Department of Chemistry, Duke University, Durham, NC 27708;
Proc Natl Acad Sci U S A. 2017 Oct 24;114(43):11356-11361. doi: 10.1073/pnas.1706860114. Epub 2017 Oct 10.
Liquids relax extremely slowly on approaching the glass state. One explanation is that an entropy crisis, because of the rarefaction of available states, makes it increasingly arduous to reach equilibrium in that regime. Validating this scenario is challenging, because experiments offer limited resolution, while numerical studies lag more than eight orders of magnitude behind experimentally relevant timescales. In this work, we not only close the colossal gap between experiments and simulations but manage to create in silico configurations that have no experimental analog yet. Deploying a range of computational tools, we obtain four estimates of their configurational entropy. These measurements consistently confirm that the steep entropy decrease observed in experiments is also found in simulations, even beyond the experimental glass transition. Our numerical results thus extend the observational window into the physics of glasses and reinforce the relevance of an entropy crisis for understanding their formation.
液体在接近玻璃态时会极其缓慢地松弛。一种解释是，由于可用状态的稀疏，熵危机使得在该状态下达到平衡变得越来越困难。验证这种情况具有挑战性，因为实验提供的分辨率有限，而数值研究落后于实验相关时间尺度的幅度超过八个数量级。在这项工作中，我们不仅缩小了实验和模拟之间的巨大差距，而且还设法创建了在实验中还没有类似的模拟构型。我们运用了一系列计算工具，获得了它们的构型熵的四个估计值。这些测量结果一致证实，实验中观察到的陡峭熵下降在模拟中也存在，甚至超出了实验的玻璃转变。因此，我们的数值结果扩展了观测窗口，深入了解了玻璃的物理性质，并增强了熵危机对于理解它们形成的相关性。
