Nitrogen-induced roughening of Re surfaces on the atomic scale

Using density-functional theory (DFT) in combination with thermodynamic considerations the morphology change in Re(11 (2) over bar1) in the presence of a nitrogen atmosphere has been investigated. In agreement with experimental observations, we find that nitrogen adsorption causes two-sided ridges consisting of atomically rough Re(13 (4) over bar2) and (31 (4) over bar2) faces to become much more favorable than the initially planar Re(11 (2) over bar1). We show that this surface faceting is due to a strong preference of N to adsorb at specific surface sites on Re(13 (4) over bar2). Our studies suggest that it is possible to stabilize atomically rough surfaces with high density of steps and kinks by the adsorption of certain strongly interacting adsorbates.