Density-functional study of Au-Cu binary clusters of small size (n = 6): Effect of structure on electronic properties

We have carried out DFT studies on the Au-Cu binary clusters of size n = 6 with a view of studying the electronic property variation with changing structure and composition in these alloys. The Au6, Cu6 and the binary clusters (with the formula AuxCu6−x, x = 1-5) minimize to triangular structures. Properties like the dipole moments show an interesting trend in these structures. With increasing Cu content these binary clusters prefer to minimize to a structure with a larger dipole moment and with increasing Au content the minimized structures prefer Au at locations that yield a smaller dipole moment. Deforming the structures to W-shape shows a red shift of the absorption maxima compared to the planar structures. The 'cap' shape and the 'W'-shape structures are of higher energy.