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arXiv 1809.00892physics.chem-ph
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极性离子固体电解质界面的有限电位移模拟:应用于NaCl(111)/水NaCl溶液

Finite electric displacement simulations of polar ionic solid-electrolyte interfaces: Application to NaCl(111)/aqueous NaCl solution

Thomas Sayer, Michiel Sprik, Chao Zhang

摘要:

Tasker III型离子晶体的极性终端携带净表面电荷以及偶极矩,并且基本上不稳定。在与电解质接触时,这种极性表面可以通过从溶液中吸附抗衡离子以形成双电层(EDL)来稳定。在先前的工作(J. Chem. Phys 147,104702(2017))中,我们报告了基于经典力场的原型模型系统(即两侧均与NaCl水溶液界面的NaCl(111)板)的分子动力学研究。模拟中的一个严重障碍是,有限宽度的平板允许固体中的电场扰动半无限系统界面处的理论电荷平衡(NaCl(111)的表面电荷密度的一半)。结果表明,应用有限宏观场$E$抵消内部电场可以恢复界面处的正确电荷补偿。在目前的工作中,我们扩展了这种方法,通过应用共轭电位移场$D$。使用$D$代替$E$作为控制变量的好处有两个方面:它不仅加快了模拟中极化的收敛,而且导致了仅涉及预先已知的结构参数的偏置位移场的简洁表达式。这使得它的可行性研究的电荷补偿现象的原型系统与密度泛函理论为基础的分子动力学(DFTMD),如在这项工作中所示。

英文摘要:

Tasker type III polar terminations of ionic crystals carry a net surface charge as well as a dipole moment and are fundamentally unstable. In contact with electrolytes, such polar surfaces can be stabilized by adsorption of counter ions from solution to form electric double layers (EDLs). In a previous work (J. Chem. Phys 147, 104702 (2017)) we reported on a classical force field based molecular dynamics study of a prototype model system namely a NaCl(111) slab interfaced with an aqueous NaCl solution on both sides. A serious hurdle in the simulation is that the finite width of the slab admits an electric field in the solid perturbing the theoretical charge balance at the interface of semi-infinite systems (half the surface charge density for NaCl(111)). It was demonstrated that the application of a finite macroscopic field $E$ cancelling the internal electric field can recover the correct charge compensation at the interface. In the present work, we expand this method by applying a conjugate electric displacement field $D$. The benefits of using $D$ instead of $E$ as the control variable are two fold: it does not only speed up the convergence of the polarization in the simulation but also leads to a succinct expression for the biasing displacement field involving only structural parameters which are known in advance. This makes it feasible to study the charge compensating phenomenon of this prototype system with density functional theory based molecular dynamics (DFTMD), as shown in this work.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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