Electronic structure of the Ba4C60 superconductor

We study the electronic structure of the superconducting body-centered-orth orhombic fulleride Ba4C60 using the local-density approximation in the dens ity-functional theory. It is found that Ba states are strongly hybridized w ith C-60 states through pentagons, explaining the observed lattice-constant differences, a>b>c. Due to this hybridization and to a rather low symmetry of the lattice causing the splitting of states, the t(1g)-derived conducti on band partially occupied by two electrons is found to be relatively wide. Fermi surfaces also show noncubic nature and contain dual quasiplanar shee ts parallel to the a-b plane in the momentum space, giving rise to a quasin esting vector parallel to the c axis.