Phase Mode in Fluctuating Charge-Density-Wave State of One-Dimensional Systems

Abstract

The lattice vibration of a one-dimensional incommensurate lattice is investigated at finite temperature by using the dynamical matrix approach. We consider the temperature region where the short range order or a charge density wave is well developed. By a transformation of coordinates, the dynamical matrix is separated into two terms, the dominant term or which coincides with that of the state with long range order. Using the perturbation theory it is found that the spectrum of the phase mode has a finite gap. It is shown that the phason mode appearing in the dynamical structure factor has the gap and broadening.