STABILITY OF CORRELATED ELECTRONIC SYSTEMS UNDER THE INFLUENCE OF THEELECTRON-PHONON INTERACTION

We have used an exact diagonalization technique to study the stability of tile t-J-Holstein and Hubbard-Holstein models under the influence of the electron-phonon interaction. Previous results have been obtaine d using frozen-phonon technique or introducing only a few dynamical ph onon modes due to the large Hilbert space. To check these results we h ave done exact diagonalization in a small cluster (four sites) includi ng all the phonon modes allowed by symmetry. We compare our results wi th those obtained by using the adiabatic approximation. Copyright (C) 1996 Elsevier Science Ltd