Comparing Ab Initio Molecular Dynamics and a Semiclassical Grand Canonical Scheme for the Electric Double Layer of the Pt(111)/Water Interface

The theoretical modeling of metal/water interfaces centers on an appropriate configuration of the electric double layer (EDL) under grand canonical conditions. In principle, ab initio molecular dynamics (AIMD) simulations would be the appropriate choice for treating the competing water-water and water-metal interactions and explicitly considering the atomic and electronic degrees of freedom. However, this approach only allows simulations of relatively small canonical ensembles over a limited period (shorter than 100 ps). On the other hand, computationally efficient semiclassical approaches can treat the EDL model based on a grand canonical scheme by averaging the microscopic details. Thus, an improved description of the EDL can be obtained by combining AIMD simulations and semiclassical methods based on a grand canonical scheme. By taking the Pt(111)/water interface as an example, we compare these approaches in terms of the electric field, water configuration, and double-layer capacitance. Furthermore, we discuss how the combined merits of the approaches can contribute to advances in EDL theory.

Automated summary

The theoretical modeling of metal/water interfaces focuses on the configuration of the electric double layer (EDL) under grand canonical conditions. Ab initio molecular dynamics (AIMD) simulations are ideal for treating water-metal interactions but are limited by small ensembles and short simulation times. Semiclassical approaches can efficiently handle the EDL model by averaging microscopic details. By combining AIMD and semiclassical methods, an improved description of the EDL can be obtained. Comparing these approaches using the Pt(111)/water interface, we analyze the differences in electric field, water configuration, and double-layer capacitance, and discuss their contributions to EDL theory.