Effect of Li Doping on Electronic and Magnetic Properties of Small Pt Clusters

Density functional theory is used to study electronic, geometric, and magnetic properties of pure Pt, (n = 2-4) and binary Pt, Li (m =1-3) clusters. Optimized equilibrium bond lengths, adsorption and binding energies, total magnetic moment, and charge distributions are determined. The adsorption energy of hydrogen atom is found to be higher for Li doped clusters. The small size of hydrogen may favor top or bridge sites depending on the cluster morphology, except for triangular Pt2Li where the tetrahedral site is favoured. Although the spin-orbit effect has not been included in the calculations, our results are in good agreement with previous spin-orbit calculations. The charge transfer and the distribution of the electronic population caused by the H adsorption give rise to a more important spin polarization of the host cluster. The coadsorption of Li and H atoms leads to an oscillatory magnetic moment for Pt clusters. Comparison of hydrogen adsorption on Pt clusters with that on Pt surfaces indicate that the Pt2 dimer seems to have similar behavior as Pt(001) surface. After the coadsorption of both Li and H, it is the Pt2Li cluster which appears as a model for Pt(111) surface.