Adsorption Structures and Energies of Cu_n Clusters on the Fe(110) and Fe3C(001) Surfaces

摘要

Spin-polarized density functional theory computations have been carried out to investigate the adsorption configurations of Cu_n (n = 1-7, 13) on the most stable Fe(110) and Fe3C(001) surfaces. On both surfaces the adsorbed Cu_n clusters favor aggregation over dispersion, and monolayer adsorption configurations are more favored thermodynamically than the two-layer adsorbed structures because of the stronger Fe—Cu interaction over the Cu—Cu bonding. On the basis of the computed adsorption energies the Fe(110) surface has stronger Cu affinity than the Fe3C(001) surface, in agreement with the experimental results. The Fe(110) surface also has stronger Cu_n aggregation energies and more pronounced charge transfer from surface to adsorbed Cu_n clusters than the Fe3C(001) surface. Different Cu_n growth mode's have been discussed accordingly.