Molecular dynamics simulation of ion mobility .2. Alkali metal and halide ions using the SPC/E model for water at 25 degrees C
Molecular dynamics simulation of ion mobility .2. Alkali metal and halide ions using the SPC/E model for water at 25 degrees C
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DOI：
10.1021/jp953050c
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发表时间：
1996-01-25
影响因子：
--
通讯作者：
Rasaiah, JC
中科院分区：
文献类型：
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作者：
Lee, SH;Rasaiah, JC
我们给出了碱金属离子（Li+, Na+, K+， Rb+和Cs+）和卤化物（F-, Cl-， Br-和I-）在25℃下的计算机模拟结果，使用SPC/E水模型和离子-水参数拟合为小簇离子的结合能。对离子-水势和水-水势进行了简单的截断，分别由均方位移和速度自相关函数计算出的迁移率彼此吻合良好。计算首次表明，阳离子和阴离子的迁移率随离子大小的变化，在不同的曲线上有不同的最大值。这与在25℃的水中观察到的实验趋势完全一致。阳离子迁移率也比以前的计算结果更符合测量值。物理学报，1994,18(6):559 - 564。然而，这里为SPC/E模型计算的卤化物的迁移率略低于实验结果。发现水在离子周围水合壳中的停留时间随着离子的大小而急剧减少。立体图像显示，离子周围的溶剂笼的结构对于较大的离子有质的不同，这意味着溶剂动力学和结构都是解释水溶液中离子迁移的重要因素。
We present results of computer simulations of the mobilities of the alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) and the halides (F-, Cl-, Br-, and I-) at 25 degrees C using the SPC/E model for water and ion-water parameters fitted to the binding energies of small clusters of ions. A simple truncation of the ion-water and water-water potentials was used, and the mobilities calculated from the mean square displacement and the velocity autocorrelation functions, respectively, were found to be in good agreement with each other. The calculations demonstrate, for the first time, cation and anion mobilities that fall on separate curves, as functions of ion size, with distinct maxima. This is in complete accord with experimental trends observed in water at 25 degrees C. The cation mobilities are also in better agreement with the measured values than the calculations done earlier (J. Chem. Phys. 1994, 101, 6964) using the TIP4P model. The mobilities of the halides calculated here for the SPC/E model are however slightly lower than the experimental results. The residence times of water in the hydration shells around an ion are found to decrease dramatically with its size. Stereoscopic pictures show that the structure of the solvent cage around an ion is qualitatively different for the larger ions, implicating both solvent dynamics and structure as important factors in explaining ion mobility in aqueous systems.