Alkali-earth metal adsorption behaviors on capped single-walled carbon nanotubes based on first-principle calculations

摘要

The adsorption behaviors of alkali-earth metals (AEMs) on the capped (5, 5) and (9, 0) carbon nanotubes (CNTs) are investigated using first-principle calculations based on generalized gradient approximation. The optimized geometry, adsorption energy, induced dipole moment, and work function, at two different sites like hexagon and pentagon, of each adatom-CNT system are calculated. The decrease of work functions, variations of Fermi levels and Bader charge transfer, in spite of CNT chirality, has almost the same regularity when the AEMs are adsorbed on the same polygon. The AEMs are off the pentagonal center of the CNTs, while for the hexagon of the CNTs, their most preferred sites are just the top of the rings. In particular, the adsorption energy and work function reduction of the AEMs on hexagon are slightly larger than that on pentagon.