Density functional study of small cobalt-platinum nanoalloy clusters

The structural, energetic, electronic and magnetic properties of small bimetallic Co_nPt_m (n+m≤5) nanoalloy clusters are investigated by density functional theory within the generalized gradient approximation. A plausible candidate for the ground state isomer and the other possible local minima, binding energies, relative stabilities, magnetic moments, the highest occupied and the lowest unoccupied molecular orbital energy gaps have been calculated. It is found as a general trend that average binding energies of Co-Pt bimetallic clusters increase with Pt doping. Planar structures of pure Co clusters become 3D with the addition of Pt atoms. CoPt₂, Co₂Pt₂, Co₃Pt₂, and CoPt₄ nanoalloys are identified as the most stable species since they have higher second finite difference in energy than the others. Pt doping decreases the total spin magnetic moment gradually. A rule for the prediction of the total spin moments of small Co-Pt bimetallic clusters is derived.