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用Material Studio软件包中的COMP ASS力场提供的9/6 Lennard-Jones势能模型,分别模拟298 K,密度为1.0 g/cm~3的水溶液中K~+、Na~+、Cl~-水化现象的分子动力学和水分子配位的微观结构。发现阳离子周围的水分子以氧原子去靠近阳离子,而阴离子周围的水分子则以其中的一个氢原子去靠近阴离子,并获得了K~+、Na~+、Cl~-的径向分布函数和配位数曲线。计算得到的K~+、Na~+、Cl~-的水化数分别为2.53、3.64、3.66,它们的水化半径分别为0.272nm、0.299 nm、0.316 nm,自扩散系数分别为1.98×10~(-5)cm~2s~(-1)、1.04×10~(-5)cm~2s~(-1)、2.08×10~(-5)cm~2s~(-1)。结果表明,3种离子的水化能力顺序为:Cl~->Na~+>K~+,自扩散系数的计算值与实验值吻合较好。K~+、Na~+、Cl~-在海水中广泛存在,本文的研究结果可为海水资源的高效开发利用提供一定的理论基础。
Using the 9/6 Lennard-Jones potential model provided by the COMP ASS force field in the Material Studio software package, the K +, Na +, Cl ~ -water in aqueous solution at 298 K and 1.0 g / cm ~ Molecular Dynamics of Phenomenon and Microstructure of Water Coordination. It is found that the water molecules around the cation come close to the cation with the oxygen atoms and the water molecules around the anion go to the anion with one of the hydrogen atoms and get the radial distribution function of K ~ +, Na ~ +, Cl ~ - and The coordination number curve. The calculated hydration numbers of K ~ +, Na ~ + and Cl ~ - are 2.53, 3.64 and 3.66, respectively, and their hydration radii are 0.272 nm, 0.299 nm and 0.316 nm respectively, and the self-diffusion coefficients are 1.98 × 10 ~ (-5) cm ~ 2s ~ (-1), 1.04 × 10 ~ (-5) cm ~ 2s ~ (-1) and 2.08 × 10 ~ (-5) cm ~ 2s ~ The results show that the order of hydration of three kinds of ions is Cl ~ -> Na ~ +> K ~ +. The calculated values of self - diffusion coefficient agree well with the experimental ones. K ~ +, Na ~ +, Cl ~ - are widely existed in seawater. The results of this paper can provide some theoretical basis for the efficient development and utilization of seawater resources.