The influence of electron-electron and electron-phonon interactions on electron charge orderings in quasi-one-dimensional systems

Abstract

We consider a model for the description of charge orderings and lattice distortions in quasi-one-dimensional narrow-band systems. The Coulomb interactions and the electron-lattice couplings are included in the model and our attention is focused on the effects of electron-phonon couplings via Coulomb forces. It has been found that these interactions can influence the electronic and lattice subsystems in a different way than the electron-phonon couplings usually considered; e.g. (i) they can contribute to the stabilization of the island-type charge ordering and induce tetramerization of the lattice in this state; (ii) they break the particle-hole symmetry and thus lead to temperature dependence of the chemical potential even in the half-filled band case; (iii) they can lead to the appearance of a disorder point at which the charge correlation functions change in character, and to anomalous dilatation of the lattice.