Metal-Insulator Transition of Peierls Type in TTT2I3 Crystals in 3D Approximation

Abstract

The metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetraceneiodide, TTT2I3, is investigated in 3D approximation. A more complete physical model of the crystal is applied which takes into account two the most important hole-phonon interaction mechanisms. The first is similar to that of deformation potential and the second one is of polaron type. The scattering on defects is also considered. The phonon polarization operator and the renormalized phonon spectrum are calculated in the random phase approximation for different temperatures applying the method of retarded Green functions. The effect of lattice distortion on the dispersion of renormalized acoustic phonons is analyzed. The Peierls critical temperature is determined.