Density functional theory calculations are widely applied to study the ALD of metals and metal oxides. Outstanding questions, such as precursor design, precursor reactivity with surfaces and their reactions with different co-reactant, can be explored by DFT calculations. In our previous work, we have investigated the coverage and stability of NHx-terminated Ru and Co surfaces , the reaction mechanism in the first half cycle after introducing metal precursors RuCp2 or CoCp2 , and reactions between plasma generated radicals and metal precursors treated NHx-terminated Ru and Co surfaces .