ISOMERS OF C-24 - DENSITY-FUNCTIONAL STUDIES INCLUDING GRADIENT CORRECTIONS

Density functional techniques are used to investigate the relative ene rgies of seven different structural isomers of C24. The traditional lo cal density approximation yields the fullerene-like isomer to be the m ost stable. As in the case of C20, the inclusion of gradient correctio ns has a dramatic effect on the relative energies. The gradient-correc ted B-LYP method yields the monocyclic ring and graphite-like isomers to be almost isoenergetic (and most stable) while the bicyclic ring, f ullerene-like, and bowl-like isomers are progressively higher in energ y. The Hartree-Fock results are quite similar to the B-LYP results. Im plications to fullerene growth mechanisms are pointed out.