Dielectric constant of water as a function of separation in a slab geometry: A molecular dynamics study
Dielectric constant of water as a function of separation in a slab geometry: A molecular dynamics study
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DOI：
10.1063/1.4919698
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发表时间：
2015-05-14
影响因子：
4.4
通讯作者：
Sakuma, Hiroshi
中科院分区：
文献类型：
--
作者：
Itoh, Hidenosuke;Sakuma, Hiroshi
与散装水相比，围合几何中的水表现出与结构和动力学有关的各种异常性质。本文采用分子动力学模拟方法，研究了石墨板状结构中水的介电常数与分离的关系。在平行于平板的法向外加电场作用下，由水分子的取向极化计算了水的介电常数。水的介电常数比散装水的降低可以通过研究板状几何中的水的结构和动力学来解释。我们在最接近石墨表面的层中发现了水分子的首选方向。计算了水分子沿平板法向的自扩散系数分布。中间层中水分子的择优取向所产生的弱氢键产生了高流动性的水分子。我们得出结论，水在平板几何中的介电常数低于大块水的介电常数，这是由于水的极化减少和水分子在中间区域的高流动性，这是由水分子的优先取向引起的。(C) 2015 AIP出版有限责任公司
Water in confining geometries shows various anomalous properties related to its structure and dynamics compared with bulk water. Here, the dielectric constant of water as a function of separation in a graphite slab geometry was studied using molecular dynamics simulations. The dielectric constants of water were calculated from the orientational polarization of water molecules when an external electric field was applied parallel and normal to the slabs. The reduction of the dielectric constant of water compared with bulk water can be explained by investigating the structure and dynamics of water in slab geometries. We found a preferred orientation of water molecules in the layer closest to the graphite surface. The self-diffusion coefficient distribution of water molecules along the direction normal to the slabs was also computed. Highly mobile water molecules in the intermediate region were generated by the weak hydrogen bonding produced by the preferred orientation of water molecules in the layer. We concluded that the dielectric constant of water in the slab geometry is lower than that of bulk water because of the reduction of the polarization of water and the highly mobile water molecules in the intermediate region arising from the preferred orientation of water molecules. (C) 2015 AIP Publishing LLC.