Ab initio theoretical study of the small fullerenes carbon(20)-carbon(36)

[摘要] Ab initio SCF Hartree-Fock calculations have been carried out on all the fullerene isomers of C$sb{20}$ to C$sb{36}. Csb{20}, Csb{24},$ and C$sb{26}$ have only one fullerene isomer each, of $Csb{2h}, Dsb6$ and $Dsb{3h}$ symmetry respectively. C$sb{28}$ has two distinct fullerene isomers, C$sb{30}$ has three, C$sb{32}$ and C$sb{34}$ have six, and C$sb{36}$ has fifteen. Their lowest energy structures were found to be of $Tsb{d} Csb{2v}, Dsb3, Csb2,$ and $Dsb{2d}$ symmetry respectively. All ground-state isomers have closed-shell electronic configurations except C$sb{26}$-$Dsb{3h}$ (open-shell $msp5Aspprimesb1)$ and C$sb{28}$-$Tsb {d}$ (open-shell $sp5{m A}sb2).$ A new mechanism, called ;;peeling;;, is proposed in order to explain the end of the C$sb2$ loss fragmentation pattern at C$sb{32}$ observed in photodissociation studies. It consists of opening the fullerene surface and excising long carbon chains. MNDO calculations show the ;;peeling;; channel to be more competitive than the C$sb2$ loss fragmentation process for C$sb{32}.$

[发布机构] Rice University