The accuracy of a method determines its applicability. Especially when predictions are the goal of computational approaches, accuracy must be sufficient to allow conclusive statements on the modelled properties. Some general statements can be made based on the extensive computational chemistry literature. DFT approaches are very accurate for the prediction of atomic structures. This has been extensively shown by comparison to structural data from experiment. Although they are slightly less accurate for transition state structures, the lack of experimental data does not allow a quantitative comparison. Reaction energies are more sensitive to the density functional chosen and can deviate by tens of kJ•mol -1 from experimental data. Main group chemistry is much more accurately modeled than transition metal chemistry. And thermochemistry is more accurate than reaction barriers. For AS-ALD modelling, GGA-type functionals are chosen which show a balanced description throughout typical ALD chemistry requirements (structures, energies, barriers). More accurate descriptions for main group chemistry are usually achieved with hybrid functionals. In all cases, the inclusion of dispersion correction schemes enhances the accuracy of structures and energies.