Structures Of C20 Research Articles

Competition between structural distortion and magnetic moment formation in fullerene C20

We investigate the effect of on-site Coulomb interactions on the structural and magnetic ground state of C20 fullerene based on density-functional-theory calculations within the local density approximation (LDA) plus on-site Coulomb corrections (LDA+U). The total energies of the high symmetry (Ih) and the distorted (D3d) structures of C20 are calculated for different spin configurations. The ground state configurations are found to depend on the forms of exchange-correlation potentials and the on-site Coulomb interaction parameter U, reflecting the subtle nature of the competition between Jahn–Teller distortion and magnetic instability in the C20 fullerene. While the nonmagnetic state of the distorted D3d structure is robust for small U, a magnetic ground state of the undistorted Ih structure emerges for U larger than 4 eV when the LDA exchange-correlation potential is employed.

The s and p character of the electronic structure of C20, C60 and C70

Abstract The electronic structure of the carbon small clusters, C20, C60 and C70, is calculated. The calculation is carried out within a Hubbard like Hamiltonian in which s- and p-electrons are taken into account. Results are obtained for the selfconsistent densities of states by means of the recursion method and are discussed and compared with those of diamond and the hexagonal lattice.