Some new structures of C-28

Twenty-four distinct structures of C-28 are considered theoretically using Hartree-Fock theory, hybrid Hartree-Fock/density functional theory (B3LYP), and second-order perturbation theory. The tetrahedral (5)A(2) State is con firmed as the electronic ground state isomer. However, a second fullerene s tructure, a singlet state of D-2 symmetry, is predicted to lie less than 2 eV above the expected global minimum. The relative energies of the various C-28 isomers can be rationalized in terms of their structural features. (C) 1999 Elsevier Science B.V. All rights reserved.