Structural instabilities in the t-J model

A simple model for including the electron-phonon coupling in the t-J model is introduced. A general framework for computing the dynamical matrix is presented and a number of electronic mean-field states in the t-J model are considered. The two different choices of quasiparticle statistics are shown to result in very different stability behavior at finite doping. The connection to the tetragonal-to-orthorhombic structural phase transition in (La,Ba)2CuO4 and other superconducting cuprates is discussed. © 1993 The American Physical Society