Hydration structure of salt solutions from ab initio molecular dynamics
Hydration structure of salt solutions from ab initio molecular dynamics
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DOI：
10.1063/1.4772761
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发表时间：
2013-01-07
影响因子：
4.4
通讯作者：
Klein, Michael L.
中科院分区：
文献类型：
--
作者：
Bankura, Arindam;Carnevale, Vincenzo;Klein, Michael L.
用基于密度泛函理论(DFT)的CAR-Parrinello(CP)分子动力学(MD)模拟方法研究了Na+、K+和Cl-离子在水溶液中的溶剂化结构。用三种不同但常用的密度泛函(BLYP、HCTH和PBE)，在广义梯度近似(GGA)水平上处理电子关联，收集了由122个水分子溶解的三个氯化钠或氯化钾离子对的CPMD轨迹。通过对DFT-GGA格式进行经验修正，分析了色散力的影响。通过离子-水径向分布函数、配位数和角分布函数研究了离子的水化特性，特别是第一溶剂化壳层的结构性质。无论是基于CHARMM力场还是基于极化模型，由CPMD模拟得到的结果与经典MD提供的结果都有显著差异。总体而言，计算的结构性能与已有的实验结果吻合较好。特别是，观测到的Na+、K+和Cl-的配位数分别为5.0-5.5、6.0-6.4和6.0-6.5，与X射线和中子散射研究相一致，但与最近对这些重要体系的其他一些计算研究有所不同。文中还讨论了产生差异的可能原因。(C)2013年美国物理研究所。[http://dx.doi.org/10.1063/1.4772761]
The solvation structures of Na+, K+, and Cl-ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na+, K+, and Cl-, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772761]