title: A translation invariant bipolaron in the Holstein model and superconductivity.
abstract: Large-radius translation invariant (TI) bipolarons are considered in a one-dimensional Holstein molecular chain. Criteria of their stability are obtained. The energy of a translation invariant bipolaron is shown to be lower than that of a bipolaron with broken symmetry. The results obtained are applied to the problem of superconductivity in 1D-systems. It is shown that TI-bipolaron mechanism of Bose-Einstein condensation can support superconductivity even for infinite chain.
authors.affiliation: Institute of Mathematical Problems of Biology, Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Pushchino, Moscow Region 142290 Russia.
authors.forename: Victor
authors.initials: V
authors.lastname: Lakhno
keywords: Bose condensate; Broken symmetry; Canonical transformation; Delocalized; Hubbard Hamiltonian; Strong coupling