Hydration of Sodium(I) and Potassium(I) Revisited: A Comparative QM/MM and QMCF MD Simulation Study of Weakly Hydrated Ions
Hydration of Sodium(I) and Potassium(I) Revisited: A Comparative QM/MM and QMCF MD Simulation Study of Weakly Hydrated Ions
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DOI：
10.1021/jp8093462
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发表时间：
2009-03-05
影响因子：
2.9
通讯作者：
Rode, Bernd M.
中科院分区：
文献类型：
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作者：
Azam, S. Sikander;Hofer, Thomas S.;Rode, Bernd M.
用量子力学/分子力学(QM/MM)和量子力学电荷场(QMCF)分子(MD)模拟方法描述了Na(I)和K(I)在水中的结构和动力学性质，并对两种方法进行了比较。用从头算量子力学在受限Hartree-Fock(RHF)水平上处理了第一和第二水化壳层。结构数据与已发表的实验和理论结果吻合较好。在12ps的模拟时间内，观察到第一壳层内发生了大量的水交换反应。在K(I)的情况下，两个壳层中的交换事件数比Na(I)的多，反映了K(I)的离子-配位键强度较弱。将“传统的”QM/MM框架与QMCF方法进行比较清楚地表明，后者是有利的，因为当应用QMCF ansatz时，由于在QM/MM MD模拟中发生的子区的耦合而引起的歧义不会演变。
Quantum mechanical/molecular mechanical (QM/MM) and quantum mechanical charge field (QMCF) molecular (MD) simulations have been performed to describe structural and dynamical properties of Na(I) and K(I) in water and to compare the two approaches. The first and second hydration shells were treated by ab initio quantum mechanics at the restricted Hartree-Fock (RHF) level. The structural data are in good agreement with previously published experimental and theoretical results. A considerable number of water exchange reactions were observed within the first shell during the simulation time of 12 ps. The number of exchange events in both shells is higher in the case of K(I) than Na(I) reflecting the weaker ion-ligand bond strength of K(I). Comparison of the "conventional" QM/MM framework with the QMCF method clearly indicates the latter to be advantageous, as ambiguities arising from the coupling of the subregions occurring in the QM/MM MD simulations did not evolve when the QMCF ansatz was applied.