A THEORETICAL-STUDY OF LIKE ION-PAIRS IN SOLUTION
A THEORETICAL-STUDY OF LIKE ION-PAIRS IN SOLUTION
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DOI：
10.1021/j100373a078
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发表时间：
1990-05-17
影响因子：
--
通讯作者：
PETTITT, BM
中科院分区：
文献类型：
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作者：
DANG, LX;PETTITT, BM
对水溶液中离子分布进行了理论研究。计算了溶液中离子对的空间分布和离子对附近水的分布。研究了溶剂结构对离子配对的影响以及配对（或解配对）过程的结构机理。我们提出了一个详细的pictureof离子在溶液中的分布与现有的实验结构研究，如中子衍射差测量和NMR实验产生的。用分子动力学方法模拟了水溶液中同电荷离子的缔合自由能。溶剂对Cl'Cl'和Na+ Na+的自由能表面（平均力的势）的影响是通过使用动态轨迹结合非玻尔兹曼采样方法的电子自由度来确定的。由于存在几个桥接水分子，阴离子对Cl'Cl'在水中的平均力势在离子接触附近有一个最小值，而阳离子Na+ Na+的平均力势基本上是排斥性的。所得结果与相同模型的场地积分方程结果基本一致。
Theoretical studies of ionic distributions in aqueous solutions have been carried out. The spatial pairdistribution in ions in solution and the distribution of water near pairs of ions have been computed. Influences of solvent structure on ion pairing and the structural mechanisms of the pairing (or unpairing) process are investigated. We present a detailed pictureof ionic distributions in solution which are compared with existing experimental structural studies such as those produced by neutron diffraction difference measurements and NMR experiments. The results of molecular dynamics simulations on the free energy of association for like-charged ions in water are presented. The influence of the solvent on the free energy surfaces (potentials of mean force) of Cl'Cl'and Na+ Na+ is determined by using a dynamic trajectory in conjunction with a non-Boltzmann sampling approach for the interionic degree of freedom. The potential of mean force for the anionic pair Cl'Cl'in water reveals a minimum near ion contact due to the presence of several bridging watermolecules, whereas the cationic Na+ Na+ potential of mean force is found to be essentially repulsive. The results are in general agreement with site-site integral equation results on the same models.