Peierls structural transition in quasi-one-dimensional organic crystals

Abstract

Peierls transition in quasi-one-dimensional organic crystals of tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ) type is studied in the case where the conduction band is half filled and Fermi dimensionless quasi momentum kF = π/2 and where the concentration of conduction electrons is reduced and the band is filled up to a quarter of the Brillouin zone, kF = π/4. In the physical model of the crystal, it was simultaneously taken into account two the most important interactions of conduction electrons with the longitudinal acoustic phonons. The dispersion equation for renormalized phonons was deduced and solved numerically. The phonon frequency dependences on quasi momentum projection along molecular wires were calculated for different temperatures. The critical temperature of transition was determined.