抄録
A possible phase diagram of the family of two-dimensional organic conductors, κ-ET2X, has so far been characterized by the strength of the mutual on-site Coulomb interaction relative to the bandwidth. In this paper, it is pointed out that there is another important parameter to categorize members of this family with quarter-filled hole bands under strong dimerization. The key parameter turns out to be the degree of splitting of the anti-bonding highest occupied molecular orbital (HOMO) bands which determines the shape of the Fermi surface, and then the possible importance of the nesting, which leads to the stability of different types of the ground states, Mott insulator and spin-density-wave (SDW) is pointed out.
