熔融Rb_2ZnCl_4的分子动力学模拟研究  

MOLECULAR DYNAMICS STUDY ON THE STRUCTURES OF MOLTEN Rb 2ZnCl 4

作　　者：程兆年[1] 丁弘[1] 雷雨[1] 

机构地区：[1]中国科学院上海冶金研究所

出　　处：《物理学报》1998年第2期260-269,共10页Acta Physica Sinica

基　　金：国家自然科学基金

摘　　要：采用在ＲｂＣｌ模拟和ＺｎＣｌ２模拟中选用的两体有效势，进行了晶态和熔融态Ｒｂ２ＺｎＣｌ４的分子动力学模拟．模拟给出了Ｒｂ２ＺｎＣｌ４６种径向分布函数，ＺｎＣｌ和ＲｂＣｌ间径向分布函数与新近的广延Ｘ射线吸收精细结构实验结果很好相符．在模拟产生的瞬态构型基础上进行了键序参数分析，研究了晶态和熔融态中的局部结构．模拟结果表明，Ｚｎ原子与其近邻Ｃｌ原子构成相当稳定的正四面体结构，并且熔融Ｒｂ２ＺｎＣｌ４中Ｚｎ／Ｃｌ正四面体结构比熔融ＺｎＣｌ２中更加稳定．大量相当稳定的（ＺｎＣｌ４）２－的存在又未明显构成网络，是熔融Ｒｂ２ＺｎＣｌ４结构的主要特征．晶态模拟未能反映晶态ＲｂＣｌ间的复杂配位。Abstract The structures of molten and crystalline states of Rb_2ZnCl_4 have been simulated by molecular dynamics with the effective potentials which had been applied in the simulations of RbCl and ZnCl_2 systems.Six radial distribution functions (RDF) simulated are presented,of which Zn Cl and Rb Cl RDFs are in good accordance with the recent EXAFS experimental results.Based on the instantaneous configurations given by the simulations,the local structures in molten and crystalline states have been studied with bond order parameter method.The results show that the Zn atom and its neighboring Cl atoms form a stable tetrahedral structure,and the Zn/Cl tetrahedral structures in molten Rb_2ZnCl_4 are stabler than those in molten ZnCl_2.The presence of a good quantity of stable (ZnCl_4) 2- units without apparent network like structures is the typical characteristics of the molten Rb_2ZnCl_4.The simulations for crystalline state did not describe the complex coordinations between Rb and Cl atoms in detail,which showed that the two body effective potentials are not enough to simulate the behaviors of Rb atoms in the crystalline Rb 2ZnCl 4.

关 键 词：Rb2ZnCl4 晶态 熔融态 分子动力学模拟 

分 类 号：O552.41[理学—热学与物质分子运动论] O73[理学—物理]