Department of Physics, Institute of Technology, National University of HochiMinh City, HochiMinh City, Vietnam.
J Phys Chem B. 2011 Jun 2;115(21):6946-56. doi: 10.1021/jp111086e. Epub 2011 May 9.
Atomic mechanism of glass formation of a supercooled simple monatomic liquid with Lennard-Jones-Gauss (LJG) interatomic potential is studied by molecular dynamics (MD) simulation. Supercooled and glassy states are obtained by cooling from the melt. Glassy state obtained at low temperatures is annealed for very long time, on the order of microsecond, and we find that glassy state remains unchanged and that the long-lived glassy state of a simple monatomic system in three dimensions is realized. We analyze the spatiotemporal properties of solid-like and liquid-like atoms that are defined by the Lindemann-like freezing criterion. The number of solid-like atoms, distributed throughout the liquid, increases with decreasing temperature toward glass transition and they form clusters. In the deeply supercooled region, almost all solid-like atoms form a single percolation cluster and its characteristic size increases sharply on further cooling. Glass formation in supercooled liquid occurs when a single percolation cluster of solid-like atoms involves a majority of atoms to form a relatively rigid solid phase. We also obtain several physical quantities of the system, including temperature dependence of mass density, Lindemann ratio, incoherent intermediate scattering function, α-relaxation time, evolution of radial distribution function, and local bond-pair orders detected by Honeycutt-Andersen analysis. We identify three characteristic temperatures related to the vitrification: a temperature at which crossover from liquid-like to solid-like dynamics occurs on cooling, the glass transition temperature, and the Vogel-Fulcher-Tammann temperature. Behavior of liquid-like atoms in glassy state has been analyzed and discussed.
采用分子动力学（MD）模拟研究了具有 Lennard-Jones-Gauss（LJG）原子间势的过冷单原子液体形成玻璃的原子机制。通过从熔体冷却获得过冷和玻璃态。在低温下获得的玻璃态经过非常长的时间（微秒量级）退火，我们发现玻璃态保持不变，实现了三维简单单原子系统的长寿命玻璃态。我们分析了由类似于 Lindemann 的冻结标准定义的固态和液态原子的时空特性。随着向玻璃转变温度的降低，分布在液体中的固态原子数量增加，并形成团簇。在超深过冷区域，几乎所有的固态原子都形成了一个单一的渗流团簇，其特征尺寸在进一步冷却时急剧增加。当固态原子的单个渗流团簇涉及大多数原子形成相对刚性的固相时，过冷液体中的玻璃形成发生。我们还获得了系统的几个物理量，包括质量密度、Lindemann 比、非相干中间散射函数、α-弛豫时间、径向分布函数的演化以及通过 Honeycutt-Andersen 分析检测到的局部键对顺序的温度依赖性。我们确定了与玻璃化转变相关的三个特征温度：冷却时从液态到固态动力学发生转变的温度、玻璃化转变温度和 Vogel-Fulcher-Tammann 温度。分析和讨论了玻璃态下液态原子的行为。
