Tuning Correlation Effects with Electron–Phonon Interactions

We investigate the effect of tuning the phonon energy on the correlation effects in models of electron–phonon interactions using DMFT. In the regime where itinerant electrons, instantaneous electron–phonon driven correlations and static distortions compete on similar energy scales, we find several interesting results including (1) A crossover from band to Mott behavior in the spectral function, leading to hybrid band/Mott features in the spectral function for phonon frequencies slightly larger than the band width. (2) Since the optical conductivity depends sensitively on the form of the spectral function, we show that such a regime should be observable through the low frequency form of the optical conductivity. (3) The resistivity has a double kondo peak arrangement