Polaronic approach to strongly correlated electron systems with strong electron-phonon interaction

Strong Coupling Approach for Strongly Correlated Electron Systems

A perturbation theory scheme in terms of electron hopping which is based on the Wick’s theorem for Hubbard operators is developed. Diagrammatic series contain single-site vertices connected by hopping lines and it is shown that for each vertice the problem splits into the subspaces with “vacuum states” determined by the diagonal Hubbard operators and only excitations around these “vacuum states...

A NUMERICAL RENORMALIZATION GROUP APPROACH FOR AN ELECTRON-PHONON INTERACTION

A finite chain calculation in terms of Hubbard X-operators is explored by setting up a vibronic Harniltonian. The model conveniently transformed into a form so that in the case of strong coupling a numerical renormalization group approach is applicable. To test the technique, a one particle Green function is calculated for the model Harniltonian

Strongly correlated electron systems.

Strongly correlated electron systems.

On the Stability of Polaronic Superlattices in Strongly Coupled Electron–phonon Systems

We investigate the interplay of electron–phonon (EP) coupling and strong electronic correlations in the frame of the two–dimensional (2D) Holstein t–J model (HtJM), focusing on polaronic ordering phenomena for the quarter–filled band case. The use of direct Lanczos diagonalization on finite lattices allows us to include the effects of quantum phonon fluctuations in the calculation of spin/charg...