LiBr溶液从低浓度到高浓度的分子动力学模拟

Molecular Dynamic Simulations of Aqueous LiBr Solutions from Low Concentration to High Concentration

中文关键词:  分子动力学模拟 溴化锂溶液 配位数 离子对

英文关键词:Molecular dynamic simulation  Aqueous LiBr solution  Radial distribution function  Coordination number  Ion pair

中文摘要:

      在ＬｉＢｒ与水的物量比分别为１：６４、１：３２、１：１６、１：８、１：４和１：３的情况下，对ＬｉＢｒ溶液从低温到高温的分子动力学模拟进行了研究。随浓度增加，锂离子的水合数呈减少趋势但同时又从Ｌｉ＾＋－Ｂｒ＾－接触离子对的数量增加中得到补偿，而Ｌｉ离子的第一配位壳层的配位数量保持不变，在高浓度ＬｉＢｒ溶液中，Ｂｒ－Ｏ之间的距离有所增加，Ｂｒ＾－Ｏ的径向分布的形状更趋于非对称，从而很好的研究了Ｂｒｙｂ

英文摘要:

      Molecular dynamic simulations of aqueous LiBr solutions from low concentration to high concentration with the molar ratio of LiBr: H2O of 1∶64，1∶32，1∶16，1∶8，1∶4，and 1∶3were carried out. The hydration number of Li ion decreases with increasing concentration, but this is compensated by the increasing number of Li+-Br- contact ion pairs, and the coordination number of the first coordination shell of Li ion keeps approximately unchanged. The hydration shell of Br ion is well defined in highly concentrated LiBr solutions with the Br--O distance a little expanding and the shape of radial distribution function of Br--O more asymmetric. The contact ion pairs of Li+-Br- appear even in more dilute solutions, and increase with the increasing of concentration. The Li+-Br- distance is obviously shorter than the sum of ionic radii of Li ion and Br ion in aqueous solution, also shorter than that in LiBr crystals. The structure of water molecules in highly concentrated solutions is nearly destroyed, and the hydrogen bond among water molecules decreases markedly, but does not disappear. The calculated diffusion coefficients of Li+,Br-,and H2O are comparable to the experimental values.