J. Phys. IV France 12 (2002) Pr9-205
DOI: 10.1051/jp4:20020396

Co-existence of charge order and spin Peierls lattice distortion in one-dimensional organic compounds

H. Seo^{1, 2}, M. Kuwabara³ and M. Ogata<sup>4

1</sup>  Correlated Electron Research Center (CERC), AlST Tsukuba Central 4, lbaraki 305-8562, Japan
²  Domestic Research Fellow, Japan Society of the Promotion of Science, Tokyo 102-8471, Japan
³  Molecular Photoscience Research Center (MPRC), Kobe University, Kobe 657-8501, Japan
⁴  Department of Physics, University of Tokyo, Tokyo 113-0033, Japan

Abstract
The ground state properties of the organic spin-Peierls compounds with one-dimensional quarter-filled band are investigated theoretically. In the strongly correlated regime, two insulating states compete to each other, which are the charge ordered state due to the inter-site Coulomb interaction, and the `dimer Mott' insulating state due to the combined effects of the electron-phonon and the on-site Coulomb interactions. In both of these states, the electron-phonon interaction further produces the lattice tetramization, which is interpreted as the spin-Peierls state.

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