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水溶液中Pb(Ⅱ)的水合结构缺乏实验数据,成键机理尚不明确.采用密度泛函理论、周期性边界计算水合物种Pb(HO)2+1-9的低能构象,探讨其结合能和稳定性,结合该离子在水溶液中的第一性原理分子动力学弛豫行为和扩展X射线吸收精细结构(EXAFS)谱特征,确定其最佳稳定构型和水合数,并通过Mulliken电荷布居、分波态密度及差分电荷密度分析其成键机理.低能优化结果表明,水合数6,7和8的构象均有可能存在,动力学弛豫过程Pb(Ⅱ)的第一和第二水合层不存在明显分界,其优势构型的水合数为6,属于偏半方位构型.22 6Pb(HO)+中Pb—O键的离子性较强,成键机理主要为Pb6p6d轨道与Pb6s-O2p反键态轨道进行耦合,存在反键态电子填充,表现为原子间电子密度的减少.
The hydration structure of Pb (Ⅱ) in aqueous solution is lack of experimental data, and the mechanism of formation of the bond is not clear.Using the density functional theory, the periodic boundary is used to calculate the low energy conformation of hydrate species Pb (HO) 2 + 1-9, Stability, combined with the first-principle molecular dynamics relaxation behavior of the ions in aqueous solution and the extended X-ray absorption fine structure (EXAFS) spectral characteristics, to determine the best stable configuration and hydration number, and through the Mulliken charge population , Partial wave density and differential charge density.The low energy optimization results show that the conformations of hydration number 6, 7 and 8 are all possible, the first and second hydration of Pb (Ⅱ) And the dominant hydration number is 6, which belongs to the semi-azimuthal configuration.22 The Pb-O bond in 6 6Pb (HO) + is more ionic and the bonding mechanism is mainly Pb6p6d or Pb6s- O2p antibonding orbital coupling, there is anti-bonding electronic filling, the performance of the electron density between atoms to reduce.