Peierls Transition in Non-Half-Filled Tight-Binding Model. I. Phase Diagram

Abstract

Peierls transition in a quasi-one-dimensional non-half-filled tight-binding model is discussed within the mean-field approximation. Even if the deviation of the Fermi level from the center of the band, denoted by µ, is not zero, the periodicity of lattice distortion is commensurate to the original lattice as far as the deviation µ is small compared to T c 0 (the critical temperature in the half-filled case). The first-order phase transition between the commensurate and incommensurate phases is discussed. The dependence of the chemical potential on the order parameter plays an important role in considering the phase diagram in µ- T plane. The temperature dependences of the order parameter and the chemical potential are calculated numerically in the commensurate phase.