Even partially hydroxylated models still use a crystalline substrate. Modeling the amorphous nature of oxides has rarely been attempted in AS-ALD (Tab. 1). In a recent study, it was found that considering the amorphous nature of the SiO2 surface (Fig. .a,b) can lead to even qualitative changes in the surface chemistry since the undercoordinated atoms at the surface are more flexible compared to atoms in a crystalline model. For the slab approach, a pseudo-amorphous model has to be used which still has a unit cell and periodic boundary conditions but provides a lessordered arrangement of atoms in the cell. This is typically developed by simulated-annealing approaches to high-temperature MD runs which computationally "melt" the crystalline surface. Si -blue, O -red, H -white. Reprint with permission from reference .