Finite field methods for the supercell modeling of charged insulator/electrolyte interfaces
Finite field methods for the supercell modeling of charged insulator/electrolyte interfaces
复制标题
带电绝缘体/电解质界面超级电池建模的有限场方法
DOI：
10.1103/physrevb.94.245309
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发表时间：
2016
影响因子：
3.7
通讯作者：
Sprik M.
中科院分区：
文献类型：
--
作者：
Zhang C;Sprik M.
与离子溶液相互作用的离子固体的表面可以通过离子交换来积累电荷。表面电荷由电解质边界处的过量电荷带补偿，形成双电层。这些双电层很难用计算凝聚相科学的超原胞方法来建模。当固体是电绝缘体（如大多数离子固体）时，问题出现了，允许在代表超晶胞中固体的平板的宽度上有有限的内部电场。平板充当电容器。储存的电荷是溶液中的不足，不能完全补偿固体表面电荷。在这里，我们展示了如何使用Stengel，Spaldin和范德比尔特[Nat.Phys.5，304（2009）1745-247310.1038/nphys 1185]开发的有限场方法来克服这些问题。我们还展示了如何可以计算的双层的电容，一旦整体的电中性的双层恢复通过应用一个有限的宏观场或零电位移。该方法被验证为一个经典的固体电解质界面模型，使用有限温度分子动力学适应的恒定场方法[C。Zhang和M. Sprik，Phys. Rev. B 93，144201（2016）2469-995010.1103/PhysRevB.93.144201]。由于电解质中的离子可以扩散穿过超晶胞边界，这个应用被证明是周期系统中极化多值性的关键说明。
Surfaces of ionic solids interacting with an ionic solution can build up charge by exchange of ions. The surface charge is compensated by a strip of excess charge at the border of the electrolyte forming an electric double layer. These electric double layers are very hard to model using the supercell's methods of computational condensed phase science. The problem arises when the solid is an electric insulator (as most ionic solids are) permitting a finite interior electric field over the width of the slab representing the solid in the supercell. The slab acts as a capacitor. The stored charge is a deficit in the solution failing to compensate fully for the solid surface charge. Here, we show how these problems can be overcome using the finite field methods developed by Stengel, Spaldin, and Vanderbilt [Nat. Phys. 5, 304 (2009)1745-247310.1038/nphys1185]. We also show how the capacitance of the double layer can be computed once overall electric neutrality of the double layer is restored by application of a finite macroscopic fieldor alternatively by zero electric displacement. The method is validated for a classical model of a solid-electrolyte interface using the finite-temperature molecular dynamics adaptation of the constant field method presented previously [C. Zhang and M. Sprik, Phys. Rev. B 93, 144201 (2016)2469-995010.1103/PhysRevB.93.144201]. Because ions in electrolytes can diffuse across supercell boundaries, this application turns out to be a critical illustration of the multivaluedness of polarization in periodic systems.