2006/12/06 by D. M. Eagles, R. M. Quick, B. Schauer · 1 citation
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Superconductivity in MgB2 and Alloys #cond-mat.other #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.75.054305
11 pages including six figures. Physical Review B, to be published
arxiv created 2006/12/06 · openalex publication_date 2007/02/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Bipolaron energies are calculated as a function of wave vector by a variational method of Gurari appropriate for weak or intermediate coupling strengths, for a model with electron-phonon interactions independent of phonon wave vector and a short-ranged Coulomb repulsion. It is assumed that the bare electrons have a constant effective mass. A two-parameter trial function is taken for the relative motion of the two electrons in the bipolaron. The energies of the bipolarons are compared with those of two single polarons as a function of wave vector for various parameter values. Results for the effective masses at the zone center are also obtained. Comparison is made with data of other authors for bipolarons in the Hubbard-Holstein model, which differs mainly from the present model in that it has a tight-binding band structure for the bare electrons.