Tc_n and Tc_n@C₇₀ Endohedral Metalofullerenes: ab initio Spin-density-functional Calculations

Ab initio spin-density-functional calculations have been performed to study the equilibrium structural, electronic, and magnetic properties of Tcn and Tc_n@C₇₀ endohedral metalofullerenes. Our results indicate that C₇₀ can encapsulate Tcn clusters with up to n=9 atoms. Except n=2, the formation of Tc_n@C₇₀ endohedral metalofullerenes is predicted to be exothermic when n≤5, while the encapsulation process becomes increasingly endothermic beyond n=5. When encapsulating into the C₇₀ cage, the geometries as well as electronic structures of the Tc cluster undergo comparative changes. Especially, compared to the isolated Tcn clusters, the total magnetic moments of Tc_n@C₇₀ reduce significantly. The analyses of the orbital population, Hirshfeld population and density of states show that electrons transfer from the Tc cluster to the carbon cage through the Tc-C efficient hybridization, which is responsible for such reduction of the whole magnetism.