Ground-state instabilities in the one-dimensional Penson-Kolb-Hubbard model.

Different kinds of instabilities (CDW , SDW , SS) in the 1D Hubbard model with pair-hopping interaction are investigated using an approximate Bethe-Salpeter equation. The study is performed at any density of electrons and for arbitrary values of the model parameters. In the absence of the on-site interaction, no transition occurs at half filling for any finite negative pair-hopping parameter, in agreement with recent results; our calculation suggests that the Penson-Kolb model (t,W ) with | W/t |< π/ sin kF behaves qualitatively like the Hubbard model (t, U). Phase diagrams of the Penson-Kolb-Hubbard model (t, U,W ) at various densities are presented. E-mail: [email protected] Permanent address: Department of Theoretical Physics, Institute for Physics and Nuclear Engineering, Institute for Atomic Physics, P.O.Box Mg-6, R-76900 Măgurele, Bucharest, Romania.