Structure and magnetic properties of adatoms on carbon nanotubes

We use ab initio methods to calculate the physical and electronic properties of carbon adatoms on different characteristic carbon nanotubes. We found that for every tube the energetically favored adsorption geometry is a ‘‘bridgelike’’ structure between two surface carbons, perpendicular to the long axis of the tube. For adsorption perpendicular or parallel to the axis, the calculations show that the adatom is spin polarized, although the magnitude of the magnetic moment depends mainly on the electronic structure of the nanotube itself.