Lindgren Eric, Swenson Jan, Müller Christian, Erhart Paul
Department of Physics, Chalmers University of Technology, Gothenburg SE-41296, Sweden.
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg SE-41296, Sweden.
J Phys Chem B. 2025 Jul 3;129(26):6613-6619. doi: 10.1021/acs.jpcb.5c00837. Epub 2025 Jun 23.
While the structural dynamics of chromophores are of interest for a range of applications, it is experimentally very challenging to resolve the underlying microscopic mechanisms. At the same time, glassy dynamics are also challenging for atomistic simulations due to the underlying dramatic slowdown over many orders of magnitude. Here, we address this issue by combining atomic scale simulations with autocorrelation function analysis and Bayesian regression, and apply this approach to a set of perylene derivatives as prototypical chromophores. The predicted glass transition temperatures and kinetic fragilities are in semiquantitative agreement with experimental data. We suggest that the remaining error could be caused by an overestimation of the intermolecular cohesion by the force field used in this work. By analyzing the underlying dynamics via the normal vector autocorrelation function, we are able to connect the β and α-relaxation processes in these materials to caged (or librational) dynamics and cooperative rotations of the molecules, respectively. The workflow presented in this work serves as a stepping stone toward understanding glassy dynamics in many-component mixtures of perylene derivatives and is readily extendable to other systems of chromophores.
虽然发色团的结构动力学在一系列应用中备受关注，但解析其潜在的微观机制在实验上极具挑战性。与此同时，由于潜在的多个数量级的显著减速，玻璃态动力学对于原子模拟来说也具有挑战性。在此，我们通过将原子尺度模拟与自相关函数分析和贝叶斯回归相结合来解决这个问题，并将这种方法应用于一组作为典型发色团的苝衍生物。预测的玻璃化转变温度和动力学脆性与实验数据半定量相符。我们认为，剩余的误差可能是由于本工作中使用的力场对分子间内聚力的高估所致。通过经由法向矢量自相关函数分析潜在动力学，我们能够将这些材料中的β弛豫和α弛豫过程分别与分子的笼状（或振动）动力学和协同旋转联系起来。本工作中提出的工作流程是迈向理解苝衍生物多组分混合物中玻璃态动力学的一块垫脚石，并且很容易扩展到其他发色团系统。
