Abstract
We study the Hubbard-Holstein model using slave-boson mean-field and a variational Lang-Firsov transformation. We identify weak and strong -ph coupling solutions, whose stability depends both on the bare -ph coupling and on the correlation strength. At mean field level the evolution from weak to strong electron-phonon coupling occurs via a first-order polaronic transition if the adiabatic parameter is below a critical value. In the strongly correlated regime and in the adiabatic limit, the region in which the weak-coupling solution is stable is sizeably enlarged with respect to the weakly correlated system and the Mott metal-insulator transition is found to be robust with respect to -ph interaction.
- Received 20 August 2005
DOI:https://doi.org/10.1103/PhysRevB.73.085120
©2006 American Physical Society