M. Kuwabara, H. Seo, M. Ogata
Jan 14, 2003
Journal of the Physical Society of Japan
The electronic properties of quarter-filled organic materials showing spin–Peierls transition are investigated theoretically. By studying the one-dimensional extended Peierls–Hubbard model analytically as well as numerically, we find that there is a competition between two different spin–Peierls states due to the tetramized lattice distortion in the strongly correlated regime. One is accompanied by lattice dimerization which can be interpreted as a spontaneous Mott insulator, while the other shows the existence of charge order of Wigner crystal-type. Results of numerical density matrix renormalization group computations on sufficiently large system sizes show that the latter is stabilized in the ground state when both the on-site and the inter-site Coulomb interactions are large.