Insight from modeling can be used to better understand the surface chemical processes in ALD and CVD. One of the foundations for the surface chemistry are the surface structures of the substrates covered with the adsorbates. From the possible surface terminations of the 13Ns, the reactivity of the different possible surfaces can be estimated. The surface structures are also needed to be able to investigate adsorption pathways as well as adatom diffusion. Earlier theoretical studies of NH3 adsorption and decomposition on GaN and InN have shown that NH3 can decompose into a variety of NHx adatoms upon adsorption on the 13Ns, often with surface NH2 being one of the most prominent species. The adsorption and decomposition on AlN have not previously been investigated in detail.