Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 51: Frontiers of Electronic-Structure Theory: Focus on the Interface Challenge V (joint session O/CPP/DS/TT)

O 51.6: Talk

Wednesday, April 3, 2019, 12:15–12:30, H9

Swipe left for water molecules? - Implicit vs explicit descriptions of liquid water at interfaces. — •Nicolas Hörmann¹, Oliviero Andreussi², and Nicola Marzari¹ — ¹Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), EPFL, CH-1015 Lausanne, Switzerland — ²Department of Physics, University of North Texas, Denton, TX 76207, USA

We present a study of relevant electrochemical interfaces, such as semiconductor-water and metal-water interfaces based on periodic density functional theory (DFT) calculations with the interface modelled with different degrees of complexity. Water at metallic surfaces is modelled within the self-consistent continuum solvation scheme (SCCS) [1] with explicit application of a potential which allows the comparison of pH dependent properties with experimental results [2,3]. In the case of semiconductors, different amounts of interfacial water are substituted with implicit solvent and observables such as the measured band alignment are obtained from thermal averaging over molecular dynamics snapshots. We find that it is necessary and sufficient to include strongly bound interfacial water molecules (dissociated or not) explicitly and replace the rest with an implicit model, in order to obtain consistent results with all-explicit simulations [4]. Based on these result we simulate the surface Pourbaix diagrams of the most stable surfaces of GaAs, GaN, GaP, CdS and anatase and rutile TiO₂.

[1] J. Chem. Phys. 136, 064102 (2012); [2] Nat Commun. 9, 3117 (2018). [2,3] NH (2018) submitted