Ab initio study of an iron atom interacting with single-wall carbon nanotubes

The interaction of an iron atom with a single-wall carbon nanotube is investigated using spin-polarized total-energy first-principles calculations. A systematic study for the atom approaching the tube surface, both from outside and inside, is presented for several configurations to determine the equilibrium distances and the binding energies. It is shown that when the atom interacts with the tube from outside, a ${3d}^7$ ${4s}^1$ effective configuration is obtained and the total magnetization is close to the atomic value. For the inside case, as a consequence of higher hybridization and a confinement effect, the magnetization decreases and the finally obtained effective configuration is ${3d}^8$ ${4s}^0.$