Theoretical investigation of 3d nanostructures on Cu surfaces:: The influence of local environment

Here, we use a first-principles approach, implemented directly in real space, which allows us to investigate the behavior of 3d nanostructures deposited onto metallic surfaces. To illustrate the flexibility of the approach, results of the exchange coupling J for 3d dimers on Cu(001) are presented. Calculations indicate that Cr and Mn dimers have antiferromagnetic alignment, while Fe, Co and Ni are stable in the ferromagnetic configuration. We also use the method to investigate the electronic structure of Fe, Co and Ni nanoclusters on Cu(001) surfaces. Our main purpose is to understand, from first principles, how electronic charge around the 3d sites is affected by the changes on the local environment associated with the lower coordination number of surfaces sites. Charge transfers, as well as charge character (s, p or d) around ferromagnetic Fe, Co and Ni clusters are investigated. If we consider a region defined by the volume per atom in the corresponding metal, we find that large charge transfers are present at cluster sites. These transfers are mainly due to a drastic decrease in the number of s and p electrons around the site, while the number of 3d electrons around the site remains practically unchanged.