2 research outputs found
Polaron and bipolaron dispersion curves in one dimension for intermediate coupling
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 vectors 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. Energies
of bipolarons are compared with those of two single polarons as a function of
wave vector for various parameter values. Results for 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.Comment: 11 pages including six figures. Physical Review B, to be publishe