Basis set effects on relative energies and HOMO-LUMO energy gaps of fullerene C₃₆

Fifteen C₃₆ isomers were examined to determine the influence that the quality of basis sets has on the geometry parameters, the relative stability and HOMO-LUMO energy gaps of fullerene isomers calculated with density functional theory. It is worthwhile to note that the geometry parameters of all C₃₆ isomers are insensitive to basis sets. On the other hand, one set of d-type polarization functions plays an important role in evaluating relative stability and HOMO-LUMO energy gaps, while diffuse functions are not effective. To obtain reliable energies, at least a double-zeta plus polarization basis set is required, and a triple-zeta plus polarization basis set is suggested to lead to accurate energies at a reasonable computational cost.