Low-spin and high-spin states of Ru-13 clusters

The electronic structure of 13-atom Ru clusters with three possible high-symmetry geometries is studied using the discrete-variational local-spin-density-functional method. All clusters are found to have two self-consistent magnetic solutions in their equilibrium configurations. The low-spin solutions are more energetically stable than the high-spin ones. The ground state is found to correspond to the icosahedral cluster. It has a magnetic moment of 4 mu(B), or 0.31 mu(B) per atom, in good agreement with the upper limit of experimental measurement, 0.29 mu(B) per atom.