INFLUENCE OF ELECTRON-ELECTRON CORRELATION ON THE JAHN-TELLER-TYPE STRUCTURAL PHASE TRANSITIONS
电子关联作用对Jahn-Teller效应引起的结构相变的影响

Starting from the Hamiltonian of Jahn-Teller effects and electron-electron correlation, we have studied the influence of electron correlation on the structural phase transitions due to the Jahn-Teller effects. By choosing different values of the parameters in the Hamiltonian, we concluded that there exist three possibilities as follows: (1) The system posesses only one structural phase transition, which corresponds to the symmetry breaking. (2) The system has a symmetry-breaking phase transition at high temperature, while the broken symmetry will be revived by decreasing the temperature. (3) The system has no phase transition throughout the whole temperature range.