Exploring Ion Dynamics in Charged Systems using Real-Space Pseudopotential Density Functional Theory

Ions are prevalent in Nature. Their dynamics is key to understanding various physical processes and chemical reactions. Proton hopping, for instance, is an important mechanism to explain the exceptionally high diffusivity of protons in water. Studies have demonstrated such proton transfer mechanisms may be vital to biochemical systems. To study proton hopping by first-principles approaches, it is common to use a supercell. These boundary conditions can add artificial correlated motion. Moreover, charged systems in supercells often adopt a uniform compensating background charge to avoid the computation of divergent electrostatic energies. However, it is not clear how well this approach reproduces the physical boundary conditions felt by the proton. We will compare supercell methods with a confined domain method where there is no need of a compensating charge within the same framework of real-space pseudopotential density functional theory.