Polarizability effects in molecular dynamics simulations of the graphene-water interface
Polarizability effects in molecular dynamics simulations of the graphene-water interface
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DOI：
10.1063/1.4789583
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发表时间：
2013-02-07
影响因子：
4.4
通讯作者：
Striolo, Alberto
中科院分区：
文献类型：
--
作者：
Ho, Tuan A.;Striolo, Alberto
量化了在水/石墨烯体系的分子动力学模拟中考虑水和石墨烯的极化率的重要性。模拟了刚性单点电荷扩展水(SPC/E)水和具有Drude极化性水的简单四位点水模型(SWM4_DP)在不可极化和可极化石墨烯表面上的薄膜。石墨烯的表面要么保持中性，要么带电，既有正负的。结果表明，SPC/E和SWM4_DP水模型对中性非极化石墨烯上的水结构性质的预测非常相似，尽管它们得到的中性非极化石墨烯上界面水的动力学性质略有不同。更明显的是，当石墨烯被用可极化的力场建模时，得到的差异更明显。特别是，石墨烯的极化性增加了界面SWM4_DP水分子的数量，使其中一个氢键指向中性表面。尽管存在这种结构差异，但只要碳原子的极化率小于α=0.878埃，就可以预测SWM4_DP水界面的动力学性质与极化率无关。在带电的石墨烯表面，石墨烯的极化性对SWM4_DP水的结构性质和某些动力学性质的影响可以忽略不计，因为表面电荷产生的静电力如预期的那样主导着极化力。对于所有情况，我们的结果表明氢键网络对水和石墨烯的极化率都不敏感。了解这些效应将如何决定中性或带电石墨烯附近离子的积累，可能对能量存储和水淡化领域的应用具有重要意义。(C)2013年美国物理研究所。[http://dx.doi.org/10.1063/1.4789583]
The importance of including the polarizability of both water and graphene in molecular dynamics simulations of the water/graphene system was quantified. A thin film of either rigid single point charge extended (SPC/E) water or polarizable simple 4-site water model with Drude polarizability (SWM4_DP) water on non-polarizable and polarizable graphene surfaces was simulated. The graphene surface was either maintained neutral or charged, positively and negatively. The results suggest that SPC/E and SWM4_DP water models yield very similar predictions for the water structural properties on neutral non-polarizable graphene, although they yield slightly different dynamical properties of interfacial water on neutral non-polarizable graphene. More pronounced were the differences obtained when graphene was modeled with a polarizable force field. In particular, the polarizability of graphene was found to enhance the number of interfacial SWM4_DP water molecules pointing one of their OH bonds towards the neutral surface. Despite this structural difference, the dynamical properties predicted for the interfacial SWM4_DP water were found to be independent on polarizability as long as the polarizability of a carbon atom is smaller than alpha = 0.878 angstrom. On charged graphene surfaces, the effect of polarizability of graphene on structural properties and some dynamical properties of SWM4_DP water is negligible because electrostatic forces due to surface charge dominate polarization forces, as expected. For all cases, our results suggest that the hydrogen bond network is insensitive to the polarizability of both water and graphene. Understanding how these effects will determine the accumulation of ions near neutral or charged graphene could have important implications for applications in the fields of energy storage and water desalination. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789583]