Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan.
J Chem Phys. 2013 Apr 7;138(13):134504. doi: 10.1063/1.4798376.
The static and dynamic properties of liquid ZnCl2 under pressure are investigated by ab initio molecular-dynamics simulations. The pressure range covers ambient to approximately 80 GPa. The ZnCl4 tetrahedra, which are rather stable at ambient pressure, are shown to deform and collapse with increasing pressure while maintaining an almost constant nearest-neighbor distance between Zn and Cl atoms. The average coordination number of Cl atoms around Zn atoms increases monotonically with pressure, from four at ambient pressure to seven at approximately 80 GPa. Although the self-diffusion coefficients of Zn and Cl atoms, d(Zn) and d(Cl), are almost the same at ambient pressure, the difference between them increases with pressure. At around 10 GPa, d(Zn) is about two times larger than d(Cl). Under further compression, this dynamic asymmetry becomes smaller. The microscopic mechanism of the appearance of the dynamic asymmetry is discussed in relation to the pressure dependence of the local structure.
通过第一性原理分子动力学模拟研究了液态 ZnCl2 在压力下的静态和动态特性。压力范围涵盖环境压力到大约 80 GPa。在环境压力下相当稳定的 ZnCl4 四面体随着压力的增加而变形和坍塌，同时 Zn 和 Cl 原子之间的最近邻距离几乎保持不变。Zn 原子周围 Cl 原子的平均配位数随压力单调增加，从环境压力下的四个增加到大约 80 GPa 时的七个。尽管 Zn 和 Cl 原子的自扩散系数 d(Zn) 和 d(Cl) 在环境压力下几乎相同，但它们之间的差异随压力而增加。在大约 10 GPa 时，d(Zn)约为 d(Cl)的两倍。在进一步的压缩下，这种动态不对称性变得更小。讨论了动态不对称性出现的微观机制与局部结构的压力依赖性之间的关系。
