Surface Science, 422, 8 (1999).
Adsorption energies and structures for N atoms on three low-index surfaces of Fe have been calculated using density functional theory (DFT) and the generalized gradient approximation (GGA). At low N coverage the adsorption energy on Fe(100) is found to be ~0.7 eV higher than on the (111) and (110) surfaces -- particularly the c(2x2)-N/Fe(100) structure with the N atoms in four-fold sites is very stable. We attribute the differences in adsorption energy to the lack of four-fold sites on the (111) and (110) surfaces. We suggest that at higher N coverages, islands with a structure similar to the c(2x2)-N/Fe(100) structure will form on the (111) and (110) surfaces.