Some new structures of C28

Twenty-four distinct structures of C28 are considered theoretically using Hartree–Fock theory, hybrid Hartree–Fock/density functional theory (B3LYP), and second-order perturbation theory. The tetrahedral 5A2 state is confirmed as the electronic ground state isomer. However, a second fullerene structure, a singlet state of D2 symmetry, is predicted to lie less than 2 eV above the expected global minimum. The relative energies of the various C28 isomers can be rationalized in terms of their structural features.