Variational approaches for electron-phonon interaction in strongly correlated systems

Abstract

In this work we present two variational approaches to the electron-phonon interaction in strongly correlated systems.

The first approach that we discussed focuses mainly on the first aspect of the problem, whereas the second one completed the picture including a faithful description of phonon properties. We tested both in the paramagnetic sector of the Hubbard-Holstein model at T = 0, focusing on ground-state properties of both electrons and phonons.