Polaron and bipolaron formation in the Hubbard-Holstein model: Role of next-nearest-neighbor electron hopping - art. no. 155105

The influence of next-nearest-neighbor electron hopping t' on the polaron a nd bipolaron formation in a square Hubbard-Holstein model is investigated w ithin a variational approach. The results for electron-phonon and electron- electron correlation functions show that a negative value of t' induces a s trong anisotropy in the lattice distortions favoring the formation of neare st-neighbor intersite bipolaron. The role of t', electron-phonon and electr on-electron interactions is briefly discussed in view of the formation of c harged striped domains.