Single-particle spectral function of the Holstein-Hubbard bipolaron
Loading...
Date
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Description
The one-electron spectral function of the Holstein-Hubbard bipolaron in one dimension is studied using cluster perturbation theory together with the Lanczos method. In contrast to other approaches, this allows one to calculate the spectrum at continuous wave vectors and thereby to study, for the first time, the dispersion and the spectral weight of quasiparticle features. The formation of polarons and bipolarons, and their manifestation in the spectral properties of the system, is studied for the cases of intermediate and large phonon frequencies, with and without Coulomb interaction. A good agreement is found with the most accurate calculations of the bipolaron dispersion available, over a large range of the electron-phonon coupling strength. Additionally, pronounced deviations of the bipolaron dispersion from a simple tight-binding band are found, which can be attributed to next-nearest-neighbor hopping processes.
12 pages, 6 figures; final version, to appear in Phys. Rev. B
12 pages, 6 figures; final version, to appear in Phys. Rev. B