The influence of the weak bond-energy dimerization on the single-particle optical conductivity of quasi-one-dimensional systems

TL;DR

This paper reexamines the single-particle optical conductivity in quasi-one-dimensional systems with weak bond-energy dimerization, revealing different behaviors in insulating and metallic regimes and matching experimental data.

Contribution

It introduces a gauge-invariant microscopic approach to analyze optical conductivity considering weak bond-energy dimerization and phenomenological relaxation effects.

Findings

Interband conductivity fits experimental data in insulating systems.

Non-Drude low-frequency response in metallic regime near 2k_F rom .

Behavior transitions to Drude-like as 2k_F deviates from .

Abstract

The single-particle contributions to the optical conductivity of the quasi-one-dimensional systems has been reexamined by using the gauge-invariant transverse microscopic approach. The valence electrons are described by a model with the weak bond-energy dimerization, while the relaxation processes are taken into account phenomenologically. It turns out that the interband conductivity of the insulating half-filled case fits well the single-particle optical conductivity measured in various CDW systems. In the metallic regime, for the doubled Fermi vector 2k_F close to \pi/a, the conduction electrons exhibit a non-Drude low-frequency response, with the total spectral weight shared between the intraband and interband channels nearly in equal proportions. For 2k_F - \pi/a not to small, the behaviour of the conduction electrons can be described as the response of a simple Drude metal.