Due to the complexity of the physical processes underlying photo-catalytic surface reactions, ab-initio computational approaches have to overcome major challenges concerning accuracy and computational costs. In particular, an efficient description of electrolytic solvent effects - which are crucial for charge driven reactions - is highly necessary. We present an implementation of the modified Poisson-Boltzmann (MPBE) model in the highly parallel and numerically efficient all-electron DFT code FHI-aims.[1] In contrast to most implicit solvent models, this technique combines dielectric solvent response with a mean-field description of solvated finite-sized ions. This has been shown to capture a majority of electrochemical solvent effects appearing in heterogeneous photo-catalysis.[2] We developed a Newton method by linearizing the MPBE and solving the resulting linearized Poisson-Boltzmann Equation by a self-consistent function-space oriented solution scheme which in contrast to common multi-grid solvers is able to exploit the specialized grids and optimized integration schemes of FHI-aims. We demonstrate the approach and its efficiency by investigating hydration and ionic effects on the solvation properties of a wide range of neutral molecules and ions. [1] Blum, V. et al., Comp. Phys. Comm. 2009, 2175-2196. [2] e.g. Kilic, M.S., Bazant, M.Z., Phys. Rev. E, 2007, 021502.

Towards first-principles modeling of electrolytic solvent effects in photo-catalytic water splitting

251st National Meeting (2016)

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