Diffusion of N Adatoms on the Fe(100) Surface

The diffusion of individual N adatoms on Fe(100) has been studied using scanning tunneling microscopy and ab initio density functional theory (DFT) calculations. The measured diffusion barrier for isolated N adatoms is $E_d=(0.92\pm 0.04)\mathrm{eV}$, with a prefactor of ${\nu }_0=4.3\mathrm{}\times {10}^{12}{\mathrm{s}}^{-1\mathrm{}}$, which is in quantitative agreement with the DFT calculations. The diffusion is strongly coupled to lattice distortions, and, as a consequence, the presence of other N adatoms introduces an anisotropy in the diffusion. Based on experimentally determined values of the diffusion barriers and adsorbate-adsorbate interactions, the potential energy surface experienced by a N adatom is determined.