Optical excitations of Peierls-Mott insulators with bond disorder

TL;DR

This paper uses DMRG to study optical excitations in disordered Peierls-Mott insulators, revealing size-dependent absorption characteristics relevant to oligoenes with bond fluctuations.

Contribution

It introduces a DMRG-based method to analyze optical properties of disordered Peierls-Mott systems, incorporating bond disorder and identifying key length scales.

Findings

Optical absorption depends on system size.

Bond disorder influences low-lying excitations.

Wave function analysis reveals relevant length scales.

Abstract

The density-matrix renormalization group (DMRG) is employed to calculate optical properties of the half-filled Hubbard model with nearest-neighbor interactions. In order to model the optical excitations of oligoenes, a Peierls dimerization is included whose strength for the single bonds may fluctuate. Systems with up to 100 electrons are investigated, their wave functions are analyzed, and relevant length-scales for the low-lying optical excitations are identified. The presented approach provides a concise picture for the size dependence of the optical absorption in oligoenes.