Implicit self-consistent description of electrolyte in plane-wave densityfunctional theory
Kiran Mathew, 1), 2) V. S. Chaitanya Kolluru, 2) Srinidhi Mula 2) and Richard G. Hennig 2)
1) Department of Materials Science, Cornell University, Ithaca, New York 14853, USA
2) Department of Materials Science, University of Florida, Gainesville, Florida 32608, USA
Kiran Mathew and V. S. Chaitanya Kolluru contributed equally to this work.
The ab-initio computational treatment of electrochemical systems requires an appropriate treatment of the solid/liquid interfaces. A fully quantum mechanical treatment of the interface is computationally demanding due to the large number of degrees of freedom involved. In this work, we describe a computationally efficient model where we model the electrode part of the interface at the density-functional theory (DFT) level, and the electrolyte part through an implicit model based on the linearized Poisson-Boltzmann equation. We describe the implementation of the model into the Vienna Ab-initio Simulation Package (VASP), a widely used DFT code, followed by validation and benchmarking of the method. We determine how the ionic concentrations in the electrolyte near the double layer is affected by the applied potential and find that the linear approximation holds for a surprisingly large potential range of at least 2V around the potential of zero charge. To demonstrate the utility of the implicit electrolyte model we apply the model to study the surface energy of Cu crystal facets in an aqueous electrolyte as a function of applied electric potential. We show that the applied potential enables the control of the shape of nanocrystals from an octahedral to a truncated octahedral morphology with increasing potential.