Structures of platinum clusters: Planar or spherical?

Platinum clusters of up to 55 atoms were studied using density functional theory with a plane wave basis set. The results show that planar platinum clusters of up to nine atoms are as stable as their three-dimensional isomers and the six-atom planar cluster is, surprisingly, more stable than its three-dimensional isomers. Among the three-dimensional platinum clusters investigated in this work, the layered clusters are found to be as stable as their spherical close-packed isomers. The high stability of planar and layered clusters suggests that it is easy to grow a platinum monolayer or multilayer. The existence of many energetically possible isomers shows a fluxional structural characteristic of platinum clusters. The effect of the spin-orbit coupling was investigated, and the results show that the relative stability of the Pt clusters is not affected although the binding energy of the cluster increases if the spin-orbit coupling is included in the calculation. Most of the platinum clusters studied here show good conductivity and ferromagnetism, which make them potentially useful as high-density magnetic data storage materials. A quantitative correlation is provided between various properties of platinum clusters and the structure and size.