One-dimensionalt−Jmodel coupled to adiabatic phonons: A numerical investigation

Abstract

The ground state of the one-dimensional $t\text{\ensuremath{-}}J$ model coupled with phonons in the adiabatic limit is numerically investigated by use of the Lanczos technique at quarter filling. Due to the interplay between the electron-electron Coulomb repulsion and electron-phonon interaction, this model shows a sequence of lattice distortions leading to the formation of charge-density waves and bond-order waves. Moderate electron-electron and electron-lattice coupling may lead to the coexistence of dimerization and tetramerization in the distortion pattern. Dimerization leads to the formation of an ``antiferromagnetic'' Mott insulator, while tetramerization gives rise to a spin-Peierls phase. By increasing the super exchange coupling, antiferromagnetism is inhibited due to the change of the distortion periodicity.