The rate of a chemical reaction is connected to the reaction barrier ∆𝐸 𝑖𝑗 ‡ via eq. 2.13. In practice, the ratio of the partition functions q is often approximated to be unity. Especially the selectivity in AS-ALD is determined by the relative values of the reaction barriers of SMIs and/or precursors on GS and NGS. If there are several possible chemical reactions in a system, the (coupled) rate equations need to be solved to derive product distributions. 𝑘 tot = ∑ 𝑘 𝑖𝑗 𝑗