Electronic structure and magnetic properties of the hydrocarbon K$_{3}$picene superconductor near the metal-insulator transition

Superconductivity has recently been observed in K-doped picene, K$_{3}$picene, which is a first organic superconductor in the hydrocarbon system with high transition temperature Tc=18K [1]. We have investigated the electronic structures and magnetic properties of K$_{3}$picene by density-functional theory. We have shown that the metal-insulator transition (MIT) is driven in K$_{3}$picene by 5{\%} volume enhancement with a formation of local magnetic moment. Active bands for superconductivity near the Fermi level (E$_{F}$ ) are found to have hybridized character of LUMO and LUMO+1 picene molecular orbitals. Fermi surfaces of K$_{3}$picene manifest neither prominent nesting feature nor marked two-dimensional behavior. By estimating the ratio of the Coulomb interaction $U $and the band width $W $of the active bands near E$_{F}$ , $U/W$, we have demonstrated that K$_{3}$picene is located in the vicinity of the Mott transition. \\[4pt] [1] R. Mitsuhashi \textit{et. al}. Nature. 464, 76 (2010)