While the exchange mechanism is almost non-existent for Li at this temperature, about 10 % of the diffusion events on Na(100) occur via an exchange process. Here, the main events are migrations of the adatom around outer-corners and kink sites. These differences are also evident in the diffusion constants obtained for simulations with and without an exchange process (see Table ). By taking exchange mechanisms into account, higher mobility of the adatoms can be observed.