Theoretical investigation of [5,5], [9,0] and [10,10] closed SWCNTs

Hartree-Fock and density functional theory calculations were performed on closed single-walled carbon nanotubes (SWCNTs) with the number of atoms up to 400. The calculated results demonstrate that the HOMO-LUMO gaps of [5,5]- and [9,0]-SWCNTs change with a different manner from those of [10,10]-SWCNTs and they are all dependent on their diameters and lengths. The calculated total energies per carbon and energy gaps of these SWCNTs demonstrate that the stability order is [10,10]>[9,0]≈[5,5]-SWCNTs with the same number of atoms. The calculated average bond lengths (ABLs) decrease with the number of atoms and the ABLs of SWCNTs with smaller diameters are larger than those of SWCNTs with larger diameters.