PhononInduced Renormalization and Interaction: An Improvement on Frohlich Transformation
Abstract
Starting from the Flohlich electronphonon model, which has a history of 50 years, a new unitary transformation is proposed to implement the perturbation treatment. Our main results are: (1)The phononinduced interaction shows a crossover from the BCSlike potential when the phonon frequency $\omega_p$ is much smaller than the Fermi energy $E_F$ to that of the small polarons when $\omega_p/E_F\ge 1$. (2)The jump of momentum distribution of electron number $n_{\bf k}$ at the Fermi surface goes to zero when the dimensionless coupling constant $\lambda$ increases to the critical value $\lambda_c\ge 1$, which means a possible broken down of the Fermiliquid description.
 Publication:

arXiv eprints
 Pub Date:
 April 2000
 arXiv:
 arXiv:condmat/0004388
 Bibcode:
 2000cond.mat..4388Z
 Keywords:

 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Superconductivity
 EPrint:
 2 figures