Subsequently, we analysed surface structures featuring corners and kinks, i.e. kink-sites (K), inner-corners (IC), outer-corners (OC). For these diffusion pathways, the determined ReaxFF activation energies show only marginal deviations of less than 0.05 eV versus the DFT-PBE target values. The perpendicular detachment of a Na adatom onto the flat terrace (K 1 →K 3 , IC 1 →IC 2 , OC 0 →OC 2 ) exhibited a diffusion barrier of 0.17 -0.22 eV (ReaxFF: 0.16 -0.18 eV) in all three systems and is highly unfavourable to their inverse processes (K 3 →K 1 , IC 2 →IC 1 , OC 2 →OC 0 ). Increasing the number of immediate neighbours leads to a thermodynamically stabilised state. Here, the incorporation of the Na atom into inner-corners and kink-sites (IC 1 →IC 0 , K 1 →K 0 ) is hardly hindered by activation barriers of less than 0.05 eV (ReaxFF: 0.06 eV). At outer corners, the migration along the step-edge (OC 0 →OC 3 ) is favoured to the vertical detachment process OC 0 →OC 2 and the atom's translation around the corner (OC 0 →OC 4 and OC 0 →OC 4 (Ex.)). Unlike Li self-diffusion, the barrier for shifting atoms around the corner via the exchange mechanism OC 0 →OC 4 (Ex.) is more than twice as high (DFT: 0.25 eV vs 0.11 eV, ReaxFF: 0.25 eV vs 0.14 eV) due to the extensive immiscibility of both metals.