Motivated by the various physical properties observed in θ-(BEDT-TTF)2X, we study the ground state of an extended Hubbard model on two-dimensional anisotropic triangular lattice at 1/4-filling with the variational Monte Carlo method. It is shown that the nearest-neighbor Coulomb interaction enhances charge fluctuation and it induces anomalous states such as the charge-ordered metallic state and triplet next-nearest-neighbor f-wave superconductivity. We consider that these results can explain the coexistence of different charge orders observed in the case of X = CsCo(SCN)4 and superconductivity in the case of X = I3. We then propose a unified view of the family of organic conductors θ-(BEDT-TTF)2X with the value of tc/tp.
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