Theoretical Description
The extended one-dimensional Hubbard model delivers a good description of the charge order transition with the on-site and nearest neighbor Coulomb repulsion U and V. It emerged that V is a crucial parameter and important for developing the charge order state. Further model calculations try to take the temperature and an interchain interaction into account. The extended Hubbard model for a single chain including inter-site and on-site interaction V and U as well as the parameter for a small dimerization which can be typically found in the (TMTTF)2X compounds is presented as follows:
where t describes the transfer integral or the kinetic energy of the electron and and are the creation respectively the annihilation operator for an electron with the spin at the th or th site. denotes the density operator. For non-dimerized systems, can be set to zero Normally, the on-site Coulomb repulsion U stays unchanged only t and V can vary with pressure.
Read more about this topic: Charge Ordering
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