ON THE PHASE-TRANSITION OF ALPHA(ET)(2)I-3

The nature of the metal-insulator (MI) transition of alpha-(ET)(2)I-3 has been studied theoretically. The effect of the on-site Coulomb interaction has been investigated at absolute zero within the Hartree-Fock approximation. If the Coulomb interaction exceeds some critical value, charge transfer occurs between different stacks and antiferromagnetic spin ordering is stabilized one-dimensionally along one stack, which results in the MI transition. It is also argued that this MI transition will lead to spin-Peierls-like distortion making the ground state nonmagnetic. Hence the present theoretical results offer a possible explanation for the intriguing feature of the MI transition of the title material.