Mean-Field Calculations for the Three-Dimensional HolsteinModel

The electron-phonon Holstein model is studied in three spatial
dimensions. It is argued that this model can be used to account for major features of the high-T_c BaPb_1-xBi_xO₃ and Ba_xK_1-xBiO₃ systems. Mean-field calculations are performed via a path integral representation of the model. Charge-density-wave order parameters and transition temperatures are obtained.