Theoretical study on the structures, properties and spectroscopies of fullerene derivatives C66X4 (X = H, F, Cl) Original Research Article

The geometrical structures, electronic properties, and spectroscopies of non-IPR (isolated pentagon rule) fullerene C66 and its derivatives C66X4 (X = H, F, Cl) have been studied by the first-principle calculations based on the density functional theory. By searching through all 4478 isomers of C66, the ground state of C66 is observed to bear Cs symmetry and have two pairs of fusion pentagons. It is found that the addition of H, F, Cl atoms to the pentagon–pentagon fusion vertex of C66 cages can form new non-IPR fullerenes such as C66X4, where the molecule C66X4 with C2v symmetry are uncovered to be the most stable among others. The Mulliken charge populations, gap energies between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO), and density of states of these unconventional fullerenes are calculated, showing that different atoms added to non-IPR C66 cages will alter the charge populations remarkably; the chemical deriving could affect the electronic structures distinctly, and improve the stability of the fullerenes. The calculated results of IR, Raman, NMR spectra of C66X4 are also presented.