In a subsequent study on this system, the authors investigated the coverage-dependent adsorption behavior of Hacac which shows a mixture of mono-and bidentate bonding modes. To this end, they applied a stochastic modeling approach, which had been proposed by Khan et al. before, based on work by the Buriak group (section 2.5.1), to obtain theoretical saturation coverages. It is also one of the few studies comparing the results from different DFs with the conclusion that they do not differ in predicted trends. The insight that different bonding modes of an inhibitor could be combined to achieve full coverage of the surface was further elaborated by the same group to combine bidentate Hacac bonding with monodentate alcohols as inhibitors. In this study, the authors used their own RSA approach to identify effective gap sizes for designing the best combination of SMIs to achieve full coverage. The idea to combine different SMIs to achieve ideal coverage of the surface has been picked up in other studies later on. For AS-ALD using trimethoxypropylsilane (TMPS), a computational study found a mixture of mono-, bi-and tridentate bonding modes on SiO2 to be the optimal combination to achieve high coverage. The need to look beyond the mono-molecular picture had been found before by the Lee and Kim groups. In a seminal work, they proposed the usage of 'precursor-inhibitors', i.e. using common ALD precursors as SMIs. The precursor-inhibitor concept has since been extended. The computational part supporting this idea showed the thermodynamic and kinetic preference for bis(N,N-dimethylamino) dimethylsilane (DMADMS) (as SMI) adsorption on OH-terminated silicon surface (NGS) over the H-terminated one (GS) (Fig. .a). The study used a minimal cluster model of the reconstructed Si(001) surface exposing one surface dimer. Their stochastic modeling approach led to the conclusion that only a fraction of the reactive surface groups (here: HO-Si groups) can be covered by the SMI due to steric hindrance (Fig. .b). While the estimated 50% of free OH groups is probably an overestimation because of the prementioned unrealistically high OH density of the a-quartz model, it clearly showed the need to retrieve coverage information of SMIs from computations to understand the blocking mechanism (see Fig. .). The authors state that finite sized objects cannot fully cover all surface sites by random, irreversible adsorption. This is also known from the packing of spheres in 3D. But packing can also be investigated with ab initio approaches. For MSA, strong adsorption on the NGS (Cu) could be computationally determined with DFT approaches while the GS (SiO2) shows a large reaction barrier towards chemisorption. The packing on the NGS was then derived by a systematic increase in coverage in the DFT computations. It was found that the adsorption energy hardly changes up to full coverage, indicating a low steric hindrance for the adsorption even at high coverages. This DFT approach of determining coverage has been further applied to TMPS on NGS (SiO2) in another computational work. Here, a theoretical coverage limit of 4.2 SMIs nm -2 was deduced from a systematic increase in coverage. The advantage of ab initio methods for coverage determination is the possibility to analyze the underlying factors. Furthermore, it could be deduced that the coverage is limited by Pauli repulsion using a quantitative bonding analysis method: the pEDA (section 2.3.4). In contrast to these works on two dielectric surfaces, the modelling of AS-ALD on a dielectric surface (GS) vs. a metal surface (NGS) shows different signatures. As first investigated by Suh et al., in this case the SMI (3-hexyne) chemisorbs on the Cu surface while it physisorbs on the SiO2 surface. They termed this approach, which they had previously demonstrated for AS-CVD, "competitive adsorption". The same difference in SMI bonding behavior has been found for aniline on SiO2 (GS, physisorption) compared to Ru and Co (NGS, chemisorption) where -in addition -catalytic decomposition of the SMI on the metal surface increased the blocking ability. Blocking a metal surface and allowing growth on a dielectric surface is another target of AS-ALD: