First-Principles Molecular Dynamics with Potential and Charge Fluctuations Applied to Au(111) in Alkaline Solutions

Electrified solid-liquid interfaces play a crucial role in energy conversion, storage, photoconversion, sensors, and corrosion processes. While computational chemistry simulations can provide detailed insights into reaction mechanisms, aligning experimental and simulation results remains a significant challenge. In this work, we introduce the FDT-SJM method for ab initio molecular dynamics simulations under potential control, where the electrode charge fluctuates around an average value following the fluctuation-dissipation theorem (FDT), and electrode charges are screened by the solvated jellium method (SJM). The FDT-SJM is developed in GPAW, a Python-based open-source DFT code. We validate this approach by simulating the Au(111) interface in pure water, KOH, LiOH, Li, and K solutions at several electrode potentials. We analyze water reorientation in response to changes in the electrode surface charge and demonstrate that the method enables the estimation of interface capacitance and the potential of zero charge, yielding values consistent with experimental data.