arXiv:1601.00648 · Physical review. B./Physical review. B
Optical conductivity of the Hubbard chain away from half filling
Alexander C. Tiegel, Thomas Veness, Piet E. Dargel, A. Honecker, Thomas Pruschke, Ian P. McCulloch, Fabian H. L. Eßler
Abstract
We consider the optical conductivity ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ in the metallic phase of the one-dimensional Hubbard model. Our results focus on the vicinity of half filling and the frequency regime around the optical gap in the Mott insulating phase. By means of a density-matrix renormalization group implementation of the correction-vector approach, ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ is computed for a range of interaction strengths and dopings. We identify an energy scale ${E}_{\mathrm{opt}}$ above which the optical conductivity shows a rapid increase. We then use a mobile impurity model in combination with exact results to determine the behavior of ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ for frequencies just above ${E}_{\mathrm{opt}}$ which is in agreement with our numerical data. As a main result, we find that this onset behavior is not described by a power law.