Commensurate-Incommensurate Charge-Density Wave Phase Transition in One-Dimensional Electron-Phonon System

The phase transition between commensurate and incommensurate phases in one-dimensional electron-phonon system is considered in the mean field approximation, taking account of the effect of all the harmonics of the charge density wave. We can show that the problem reduces to that of the G-L equation with a periodic boundary condition. The equation can be solved exactly at T = 0K and T ∼TC in the case of nearly 1/3-filled band. A part of the phase diagram in the µ-T plane is given. We also discuss the case of nearly half-filled band briefly.