Using first principles total energy calculations,the surface energies of Mo and W before and af-ter adsorbing Rh thin films in [111] and [110] orientations are calculated.The calculation results indicate that clean (111) surfaces of both Mo and W cannot transform to {110} facets,in agreement with experimental observations.When the coverage of Rh arrives at one physical monolayer,Rh/Mo(111) still cannot facet to {110},while under a favorable energy condition for the transforma-tion,Rh/W(111) may facet to {110}.