LiCl急冷玻璃形成过程中局部结构的分子动力学模拟——基于周期性边界条件的Voronoi多面体计算

A COMPUTER SIMULATION ON LOCAL STRUCTURE IN LiCl QUENCHING PROCESS——THE COMPUTATION OF THE VORONOI POLYHEDRON FOR THE SIMUIATION UNIT CELL EXTENDED WITH PERIODIC BOUNDARY CONDITION

我们建立的在周期性边界条件下由定义直接构算模拟立方元胞中各粒子Voronoi多面体的逐次切割法,以及对熔融LiCl在急冷过程的四个温度下共二万余个Voronoi多面体的面数、体积、侧面多边形、侧面面积等信息的统计分析结果。讨了退化和非退化的Voronoi多面体与计算精度的关系。计算清楚地表明,不同的相具有不同的局部结构特征。特别值得注意的是在298K,系统的Voronoi多面体分布极为集中。文中还根据Voronoi多面体的信息计算了各温下Li^+离子和Cl^-离子的配位数和配位数的组成。

A method of constructing and computing the Voronoi polyhedron of every ion in the simulation unit cell extended with periodic boundary condition directly by definition without resorting to any similarity, so called successive cutting method is described. According to the phase orbit got by the simulation of LiCl system with molecular dynamics method and considering the periodic boundary condition, more than 20,000 Voronoi polyhedrons have been constucted and computed, At each of the following temperatures, 900K, 698K,498K and 298K,we have calculated about 5,000 Voronoi polyhedrons. The results of statistical analysis of all information about these Voronoi polyhedrons including the number of side faces, volume, vertex, edge, and polygon of side face are reported. The statistical analysis shows clearly that different phase of the LiCl system possesses different character of the local structure. It merits our attention that at 298K the distribution of the numbers of side faces of Voronoi polyhedrons is very concentrative. Therefore we define the coordination number of Li^+ ion and Cl^- ion by the volume and its component of the Voronoi polyhedron.The coordination number and its composition had baen evalua ted too.