Phonon Dynamics and Structural Instability in Quasi One-Dimensional Conductors with Interchain Interaction

Abstract

The structural energy, the phonon dynamics, and the stability condition in quasi one-dimensional (1-D) conductors are discussed with the pseudopotential model including the Coulombic interchain interaction. The following cases are considered; (A) single kind and (B) two kinds of chains in crystal. For case (A), the type of mode coupling and the phonon dispersion are investigated in various states (T>T_p with and without QLRO and T<T_p with LRO), and the relation of the structural energy to the phonon dispersion is indicated. When only one kind of chains is in the ordered state in case (B), the mode coupling also takes place in the disordered chain by the effect of the ordered chain and the nature of the phonon modes is clarified. The sliding motion of CDW in individual chain in 3-D crystals is also discussed.