Coulomb repulsion dependences of SDW solitons and polarons in the one dimensional Hubbard model — Lifting of degeneracies in solitions and polarons in the strong correlation regime —

Abstract

Dependences of SDW solitons and polarons on the Coulomb repulsion U are studied in the one dimensional (1D) Hubbard model. In the weak coupling regime with small U, the solitons and polarons have wide extensions with smooth envelopes and degeneracies related to the directions of spin and the interface types. In the strong correlation regime with large U, they turn out to localize onto only several sites and the degeneracies are lifted leaving only several types of solitons and polarons to have small formation energies. Crossover of the low energy charged soliton and polaron occurs at a U beyond which the polaron becomes the lowest in energy. In a more general PPP model, it is shown that SDW, CDW and BOW solitons and polarons have one kind of exact degeneracy. They have two kinds of approximate degeneracies holding only in the weak coupling limit. The pattern of the degeneracies is different in SDW solitons and polarons from CDW and BOW ones.