On Mg(101 ! 1), all processes studied can occur at ambient conditions. In the temperature range between 200 and 300 K, dimer and trimer separation, edge evaporation, and the exchange step-up process are activated. In addition, concerted dimer propagation proceeds at about 200 K. At this point, we would like to refer to the Supporting Information, which summarizes all calculated data. SI Table V and SI Table show the pre-exponential factors, activation energies, room-temperature rate constants, and activation temperatures for the terrace selfdiffusion processes for the PBE and BEEF-vdW functionals, respectively. Corresponding schematic representations and energy profiles are provided in SI Figure . In addition, overviews of all investigated diffusion processes on Mg(0001) are available in SI Figure and on Mg(101 ! 1) in SI Figure . The corresponding pre-exponential factors, activation energies, room temperature rate constants, activation temperatures, and energy profiles may be found in SI Table VIII, SI Figure , SI Table , and SI Figure .