Stability, structural, and magnetic phase diagrams of ternary ferromagnetic 3d-transition-metal clusters with five and six atoms.

We report a theoretical investigation of free-standing Fe(x)Co(y)Ni(z) ternary clusters with x + y + z = 5 and 6. Our study is performed within density functional theory as implemented in the GAUSSIAN 03 set of programs and with the BPW91/SDD level of theory. We analyze the geometries, chemical order, local and total magnetic moments, binding energies, excess energies, and second difference in the energy in the whole range of composition, from which structural, magnetic, and stability phase diagrams are predicted for these cluster sizes. We determine the optimal stoichiometries for these clusters as regards the maximum total magnetic moment and stability.