Density functional calculations of electronic structure and magnetic properties of the hydrocarbon K_3picene superconductor near the metal-insulator transition

摘要

We have investigated the electronic structures and magnetic properties of a newly discovered hydrocarbon superconductor,K_3picene,having T_c =18 K.We have shown that the metal-insulator transition is driven in K_3picene by 5% volume enhancement with the formation of the local magnetic moment. Active bands for the superconductivity near the Fermi level (E_F) have hybridized character of LUMO and LUMO + 1 of the picene molecule. Fermi surfaces of K_3picene manifest neither prominent nesting feature nor marked two-dimensional behavior. By estimating the ratio of the Coulomb interaction, U, and the bandwidth, W, of the active bands near Ef, we have demonstrated that K_3picene is located in the vicinity of the Mott transition. Our findings suggest that K_3picene is a strongly correlated electron system.