应用ABEEMσπ极化力场对Zn^(2+)水溶液配位微结构和水交换反应进行分子动力学模拟研究  

Study on Coordination Microstructure and Water Exchange Reaction of Zn^(2+) Aqueous Solutions through Molecular Dynamics Simulations Using the ABEEMσπ Polarizable Force Field

作　　者：赫兰兰[1] 郭宇[1] 赵健[1] 姜新蕊 杨忠志[1] 赵东霞[1] 

机构地区：[1]辽宁师范大学化学化工学院

出　　处：《物理化学学报》2016年第12期2921-2931,共11页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21133005;21473083);辽宁省教育厅一般项目(L2014426);辽宁师范大学实验室开放项目(cx20160111)资助~~

摘　　要：应用ABEEMσπ极化力场,对Zn^(2+)水溶液体系进行分子动力学模拟,探讨Zn^(2+)的配位微结构和配体水交换反应。水分子模型采用ABEEM-7P精细水模型。模拟后对体系结构、电荷及动力学性质进行细致分析。结构分析表明,平衡体系中Zn^(2+)的第一层配位数为6,这与实验值是一致的。水交换反应过程中,溶剂水由O―Zn―O角分线斜上(下)方进攻Zn^(2+),配位水由O―Zn―O角分线斜下(上)方逐渐远离。极化力场模拟时Zn^(2+)与交换水间的距离变化波动较大,而固定电荷力场的波动较小。模拟发现,极化力场的径向分布函数能精细地展示第二、三层配体的配位微结构,第二配位层存在靠近Zn^(2+)的亚壳层,能与第一水合层发生水交换反应,充分体现了Zn^(2+)的极化效应。本文阐明了水交换反应中,Zn^(2+)位点电荷与交换水中氧原子孤对电子位点电荷的规律性变化,从电荷的角度解释了水交换反应的合理性。ABEEMσπ极化力场模拟Zn^(2+)水溶液获得第一水合层的平均配位驻留时间为2.0×10-9s,在实验值范围内,说明ABEEMσπ极化力场可以合理地模拟Zn^(2+)水溶液体系。Coordination microstructure and water exchange of Zn2＋ aqueous solution were studied through molecular dynamics simulations based on the ABEEMσπ polarizable force field with the precise ABEFM-7P model. Structural and dynamical properties were investigated in detail. We show that the first-shell water coordination number is six, which is in agreement with the experimental value. During the water exchange process, H2O, which attacks or leaves the first solvation shell of Zn2＋, is orientated on the upper or lower inclined side of the ∠O-Zn-O bisector. The distance change between Zn2＋ and the oxygen atom of the exchange water for the polarizable force field fluctuates more than that observed for the fixed charge force field. The radial distribution function （RDF） of the polarizable force field showed clearly the microstructure of the second and third solvation shells. The subshell of the second solvation shell was found to exchange with the first solvation shell. The polarizable effect of Zn2＋ has been fully expressed. The charges of the Zn2＋ site and the lone-pair sites in exchange water regularly change, demonstrating the rationality of water exchange. The mean ligand residence time （2.0 × 10^-9 s） of the first-shell water produced by the ABEEMσπ polarizable force field is within the range of the experimental value. Zn2＋ aqueous solution can be reasonably simulated through the ABEEMσπ polarizable force field.

关 键 词：ABEEMσπ极化力场 分子动力学模拟 水交换反应 径向分布函数 电荷分析 平均配位驻留时间 

分 类 号：O641.4[理学—物理化学] O643.1[理学—化学]