Periodic supercell models of electric double layers formed at the interface between a charged surface and an electrolyte are subject to serious finite size errors and require certain adjustments in the treatment of the long-range electrostatic interactions. In a previous publication Zhang and Sprik [Phys. Rev. B 94, 245309 (2016)], we have shown how this can be achieved using finite field methods. The test system was the familiar simple point charge model of a NaCl aqueous solution confined between two oppositely charged walls. Here this method is extended to the interface between the (111) polar surface of a NaCl crystal and a high concentration NaCl aqueous solution. The crystal is kept completely rigid and the compensating charge screening the polarization can only be provided by the electrolyte. We verify that the excess electrolyte ionic charge at the interface conforms to the Tasker 1/2 rule for compensating charge in the theory of polar rock salt (111) surfaces. The interface can be viewed as an electric double layer with a net charge. We define a generalized Helmholtz capacitance C_H which can be computed by varying the applied electric field. We find $C_{\mathrm{H}}=8.23\mu {Fcm}^{-2}$, which should be compared to the $4.23\mu {Fcm}^{-2}$ for the (100) non-polar surface of the same NaCl crystal. This is rationalized by the observation that compensating ions shed their first solvation shell adsorbing as contact ions pairs on the polar surface.

中文翻译：

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极性NaCl（111）表面与NaCl水溶液之间的界面处的电荷补偿

在带电表面和电解质之间的界面处形成的双电层的周期性超级电池模型会受到严重的有限尺寸误差的影响，并且在处理长距离静电相互作用时需要进行某些调整。在先前的出版物中，Zhang和Sprik [Phys。B版94，245309（2016）]，我们已经展示了如何使用有限域方法来实现这一目标。测试系统是被限制在两个带相反电荷的壁之间的NaCl水溶液的熟悉的简单点电荷模型。在此，此方法扩展到了NaCl晶体的（111）极性表面和高浓度NaCl水溶液之间的界面。晶体保持完全刚性，并且只能通过电解质来提供极化屏蔽作用的补偿电荷。我们验证了界面上多余的电解质离子电荷符合塔克勒1/2准则，以补偿极性岩盐（111）表面理论中的电荷。该界面可以看作是带净电荷的双电荷层。我们定义了广义亥姆霍兹电容C _H可以通过改变施加的电场来计算。我们发现$C_{\mathrm{H}}=8.23\mu {FC米}^{-\mathrm{2个}}$，应与 $4.23\mu {FC米}^{-\mathrm{2个}}$对于同一NaCl晶体的（100）非极性表面。这是通过观察得到的，补偿离子释放出它们的第一个溶剂化壳，并以接触离子对的形式吸附在极性表面上。