A chemical potential equalization approach to constant potential polarizable electrodes for electrochemical-cell simulations.

Atomistic modeling of electrochemical systems is one of the most challenging topics in the field of molecular simulations. We derive the equations for modeling constant potential polarizable electrodes in electrochemical-cell simulations based on the chemical potential equalization principle. They reduce to those derived by Siepmann and Sprik [J. Chem. Phys. 102, 511 (1995)], later arranged by Reed, Lanning, and Madden [J. Chem. Phys. 126, 084704 (2007)] under some assumptions. The present approach clarifies the physical meaning of the total energy of a system that includes classical polarizable electrodes, which is important in order to analyze the energetics of chemical phenomena at electrode-electrolyte interfaces. The effects of the Hubbard U parameter of an electrode atom are discussed in connection with the perfect conductor limit for a metal electrode.