Published online by Cambridge University Press: 28 February 2011
High-spin 13-atom transition metal cluster are studied using the linear-combination-of-Gaussian-type-orbital, local-density-functional, all-electron method. The high degeneracy associated with high symmetry is exploited to find geometry optimized clusters that have the highest contribution by spin to the magnetic moment subject to a constraint. The constraint is that the cluster not distort by the Jahn-Teller mechanism and thus have the lowest possible orbital-angular-momentum component of the magnetic moment. Pure 13-atom nickel and iron clusters are approximately icosahedral because of increased symmetry-required orbital degeneracy for electrons of different spins in this largest point group. The central atom of the icosahedral iron cluster has been varied to optimize the spin of the cluster keeping the orbital contribution to the magnetic moment quenched. Varying the central atom under this constraint can alter the magnetic moment by 20%, relative to the pure iron cluster.