Calvo Florent, Bogdan Tetyana V, de Souza Vanessa K, Wales David J
Laboratoire de Chimie et Physique Quantiques, IRSAMC, Université Paul Sabatier, 118 Route de Narbonne, Toulouse Cedex, France.
J Chem Phys. 2007 Jul 28;127(4):044508. doi: 10.1063/1.2749725.
This paper presents an analysis of the thermodynamics of a model glass former. We have performed equilibrium sampling of a popular binary Lennard-Jones model, employing parallel tempering Monte Carlo to cover the crystalline, amorphous, and liquid regions of configuration space. Disconnectivity graphs are used to visualize the potential energy landscape in the vicinity of a crystalline geometry and in an amorphous region of configuration space. The crystalline global minimum is separated from the bulk of the minima by a large potential energy gap, leading to broken ergodicity in conventional simulations. Our sampling reveals crystalline global minima that are lower in potential energy than some of the previous candidates. We present equilibrium thermodynamic properties based on parallel tempering simulations, including heat capacities and free energy profiles, which depend explicitly on the crystal structure. We also report equilibrium melting temperatures.
本文对一个模型玻璃形成体的热力学进行了分析。我们对一个流行的二元 Lennard-Jones 模型进行了平衡采样,采用并行回火蒙特卡罗方法来覆盖构型空间中的晶体、非晶和液体区域。使用不连通图来可视化晶体几何结构附近以及构型空间非晶区域中的势能面。晶体全局最小值与大部分最小值之间存在很大的势能间隙,这导致传统模拟中遍历性的破坏。我们的采样揭示了势能比一些先前候选值更低的晶体全局最小值。我们基于并行回火模拟给出了平衡热力学性质,包括热容和自由能分布,这些性质明确依赖于晶体结构。我们还报告了平衡熔点温度。