Sayer Thomas, Cox Stephen J
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
J Chem Phys. 2020 Oct 28;153(16):164709. doi: 10.1063/5.0022596.
Attaining accurate average structural properties in a molecular simulation should be considered a prerequisite if one aims to elicit meaningful insights into a system's behavior. For charged surfaces in contact with an electrolyte solution, an obvious example is the density profile of ions along the direction normal to the surface. Here, we demonstrate that, in the slab geometry typically used in simulations, imposing an electric displacement field D determines the integrated surface charge density of adsorbed ions at charged interfaces. This allows us to obtain macroscopic surface charge densities irrespective of the slab thickness used in our simulations. We also show that the commonly used Yeh-Berkowitz method and the "mirrored slab" geometry both impose vanishing integrated surface charge densities. We present results both for relatively simple rocksalt (1 1 1) interfaces and the more complex case of kaolinite's basal faces in contact with an aqueous electrolyte solution.
如果想要深入了解系统行为并获得有意义的见解，在分子模拟中获得准确的平均结构性质应被视为一个先决条件。对于与电解质溶液接触的带电表面，一个明显的例子是离子沿垂直于表面方向的密度分布。在这里，我们证明，在模拟中通常使用的平板几何结构中，施加电位移场D可以确定带电界面上吸附离子的积分表面电荷密度。这使我们能够获得宏观表面电荷密度，而与模拟中使用的平板厚度无关。我们还表明，常用的Yeh-Berkowitz方法和“镜像平板”几何结构都施加了消失的积分表面电荷密度。我们给出了相对简单的岩盐（1 1 1）界面以及高岭石基面与电解质水溶液接触这一更为复杂情况的结果。
