## Abstract

We examine two recently proposed models of charge ordering (CO) in the nominally (formula presented)-filled, quasi-one-dimensional (1D) organic charge-transfer solids (CTS). The two models are characterized by site charge density “cartoons” (formula presented) and (formula presented) respectively. We use the Peierls-extended Hubbard model to incorporate both electron-electron (formula presented) and electron-phonon (formula presented) interactions. We first compare the results, for the purely electronic Hamiltonian, of exact many-body calculations with those of Hartree-Fock (HF) mean-field theory. We find that HF gives qualitatively and quantitatively incorrect values for the critical nearest-neighbor Coulomb repulsion (formula presented) necessary for (formula presented) order to become the ground state. Second, we establish that spin-Peierls order can occur in either the (formula presented) and (formula presented) states and calculate the phase diagram including both on-site and intrasite (formula presented) interactions. Third, we discuss the expected temperature dependence of the CO and metal-insulator transitions for both (formula presented) and (formula presented) CO states. Finally, we show that experimental observations clearly indicate the (formula presented) CO in the 1:2 anionic CTS and the (formula presented) materials, while the results for (formula presented) with narrower one-electron bandwidths are more ambiguous, likely because the nearest-neighbor Coulomb interaction in these materials is near (formula presented).

Original language | English (US) |
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Number of pages | 1 |

Journal | Physical Review B - Condensed Matter and Materials Physics |

Volume | 67 |

Issue number | 11 |

DOIs | |

State | Published - Jan 1 2003 |

Externally published | Yes |

## ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics