There are many reports in the AS-ALD literature that the number of nucleation sites is crucial for selectivity. Most prominently, for oxide surfaces, the density of reactive OH-groups at the surface is important. For example, for tungsten ALD, it has been experimentally found that suppressing the formation of hydroxyl groups during the substrate cleaning process of NGS SiO2 (the so-called piranha clean) extends the selectivity window for the AS-ALD process. Also, suppressing surface oxidation of the silicon substrate (NGS) leads to selective adsorption on the OH-terminated SiO2 GS. However, in most computational studies, idealized surface models are used. For SiO2 for example, most often the (0001) facet of its a-quartz modification (Fig. .c) is used (Tab. 1 and 2) which leads to a highly ordered pattern of hydrogen bonds at the surface of the slab and an unrealistically high OH density of 9.34 OH nm -2 which exceeds the average experimental density of 4.9 OH nm -2 . Some studies thus used partially hydroxylated cluster models or periodic slabs. For elemental semiconductors, surface termination also plays a crucial role. In the case of silicon, the bare surface, H, and OH-termination have been investigated. Here, well established computational models exist, and the main question regards the matching of computational model and experimental conditions. For the modeling of metal surfaces, low-index surfaces are usually taken as models for the often-nanocrystalline substrates used in experiments. Here, frequently the decisive question is whether a native oxide layer exists on the metal surface. Modelling metal oxides is quite challenging and rarely investigated in AS-ALD. Often, neither the stoichiometry nor the surface corrugation are well understood. For Cu and CuxO it has recently been found that their reactivity is very similar towards aromatic inhibitor molecules. The reduction of cupric or cuprous oxide was hypothesized to be facilitated by inhibitor deprotonation for methylsulfonic acid (MSA) based on thermodynamic considerations.