Beyond liquids, sDFT can also been employed to describe complex solid-solid and solidliquid interfaces in condensed-phase systems. As prototypical examples, Pavanello and coworkers have applied their implementation of sDFT with periodic boundary conditions to a water bilayer on a platinum surface as well as to a complex system relevant for catalysis, consisting of a thiophene molecule physisorbed on a molybdenum sulfide monolayer, which is deposited on top of an α-alumina support (see Fig. ). Here, each layer is treated as a separate subsystem. Efficiency gains compared to a conventional KS-DFT treatment can be obtained by adapting the k-point grid for each subsystem. For the molecular subsystem(s), considering only the Γ-point is sufficient, and also for the alumina layer the k-point grid can be reduced compared to the one used for the metal-lic layer. A similar strategy was applied for water and benzene on molybdenum sulfide surfaces . To tackle even larger systems, sDFT can be further combined with orbital-free DFT for metallic subsystems, as was demonstrated for water and CO 2 on aluminium surfaces .