Stability, electronic and magnetic properties, and reactivity of icosahedralMCo12clusters

The stability, electronic and magnetic properties, and reactivity of icosahedral M${\mathrm{Co}}_{12}$ clusters are studied using the discrete variational local-spin-density-functional method, where M=Ti, V, Cr, Mn, Fe, Co, and Ni. By means of the binding-energy calculation, we obtained the M-Co bond length of the clusters and compared their relative stability. We calculated the electronic structure of the clusters in their equilibrium configurations. The calculated results show that all the clusters have metallic character, and that the clusters with M being Ti, Mn, or Co have closed electronic shells while the others have open electronic shells and are expected to distort further. The results also indicate that the cluster moment is reduced by the substitution of the central Co atom with an M atom, and that the average moment per atom of all clusters is larger than that of the bulk Co. Based on the results of electronic structures, we further analyzed the reactivity of the clusters toward ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, and CO molecules and found a strong dependence on the central M atom. Our results compare well with the available experimental results.