A first principles study of Rh on Mo(111) and W(111) surfaces

Using local density functional calculations, we studied the morphological c hanges of Mo(111) and W(111) upon the adsorption of an ultrathin film of Rh , The unusual relaxations induced by Rh on Mo(111) and W(111) surfaces shou ld be caused by competing several factors such as Smoluchowski smoothing ef fect: change of atomic interactions, and charge transfer between overlayer and substrate, It was found that both Rh/Mo(111) and Rh/W(111) can facet to {211} when the Rh coverage reaches one physical monolayer. The {211} facet s should coexist with the (111) planar surfaces, which is substantially due to thermodynamic effects, and the onset annealing temperature for inducing facets of Rh/Mo(111) and Rh/W(111) should be higher than that for some oth er metal overlayers such as Pd. (C) 2001 Elsevier Science B.V. All rights r eserved.