Optical excitations in a one-dimensional Mott insulator
Abstract
The density-matrix renormalization-group (DMRG) method is used to investigate optical excitations in the Mott insulating phase of a one-dimensional extended Hubbard model. The linear optical conductivity is calculated using the dynamical DMRG method and the nature of the lowest optically excited states is investigated using a symmetrized DMRG approach. The numerical calculations agree perfectly with field-theoretical predictions for a small Mott gap and analytical results for a large Mott gap obtained with a strong-coupling analysis. Is is shown that four types of optical excitations exist in this Mott insulator: pairs of unbound charge excitations, excitons, excitonic strings, and charge-density-wave (CDW) droplets. Each type of excitations dominates the low-energy optical spectrum in some region of the interaction parameter space and corresponds to distinct spectral features: a continuum starting at the Mott gap (unbound charge excitations), a single peak or several isolated peaks below the Mott gap (excitons and excitonic strings, respectively), and a continuum below the Mott gap (CDW droplets).
Cite
@article{arxiv.cond-mat/0208480,
title = {Optical excitations in a one-dimensional Mott insulator},
author = {Eric Jeckelmann},
journal= {arXiv preprint arXiv:cond-mat/0208480},
year = {2009}
}
Comments
12 pages (REVTEX 4), 12 figures (in 14 eps files), 1 table