Electrodes in aqueous electrolyte: modeling challenges and surprises

The electrochemical interface is challenging to model solely from first principles because of the long length and time scales of interfacial processes. Approximating the properties of the charged interface by extrapolation from the neutral interface can lead to qualitatively incorrect descriptions (e.g., of the adsorbate geometry). Coupling ab initio methods with more scalable methods such as classical molecular dynamics or continuum modeling can make this charging problem tractable. Here, I discuss the challenges of modeling charged electrochemical interfaces. I then focus on three explicitly charged interfaces and the connections to experimental observables that can be accessed through charging, including geometry changes, the capacitance, and the potential of maximum entropy.