Pseudopotential Formalism for Structural Energy and Dynamical Motions in Quasi One-Dimensional Conductors

Abstract

The structural energy and the dynamical motions in quasi one-dimensional (1-D) conductors are investigated microscopically from the view point of the pseudo-potential model for such systems developed by the author. When the 1-D Peierls instability is well-developed, the ±2 k F Fourier components of the pseudopotential is absorbed into the unperturbed Hamiltonian. The stabilizing energy of the Peierls state is quartic with respect to the quasi long-range order (QLRO) parameter. Explicit expressions are given for the structural energy including the commensurability energy. Including the effect of the QLRO into the phonon Hamiltonian, the soft phonon (phason mode) and the phonon with an energy gap (amplitude mode) are naturally derived at | q |=2 k F = Q . The phason dispersion near ± Q is derived and compared with the result derived by the conventional method.