Optical conductivity of the one-dimensional dimerized Hubbard model at quarter filling

TL;DR

This paper studies the optical conductivity of a one-dimensional dimerized Hubbard model at quarter filling, revealing how dimerization and nearest-neighbor interactions shape the spectral features in the Mott insulating phase.

Contribution

It provides a detailed numerical analysis of the optical spectra using dynamical density-matrix renormalization group, clarifying the roles of different interactions in spectral structures.

Findings

Dimerization and nearest-neighbor repulsion primarily determine spectral features.

On-site repulsion has a secondary influence on the optical conductivity.

Results have implications for understanding optical properties of Bechgaard salts.

Abstract

We investigate the optical conductivity in the Mott insulating phase of the one-dimensional extended Hubbard model with alternating hopping terms (dimerization) at quarter band filling. Optical spectra are calculated for the various parameter regimes using the dynamical density-matrix renormalization group method. The study of limiting cases allows us to explain the various structures found numerically in the optical conductivity of this model. Our calculations show that the dimerization and the nearest-neighbor repulsion determine the main features of the spectrum. The on-site repulsion plays only a secondary role. We discuss the consequences of our results for the theory of the optical conductivity in the Bechgaard salts.