Посилання:Interaction of strongly correlated electrons
and acoustical phonons / V.A. Moskalenko, P. Entel, D.F. Digor // Физика низких температур. — 2006. — Т. 32, № 4-5. — С. 609–633. — Бібліогр.: 34 назв. — англ.
Підтримка:This work was supported by the Heisenberg—Landau
Program. It is a pleasure to acknowledge discussions
with Prof. N. Plakida and Dr. S. Cojocaru and
to thank Vadim Shulezhko for asistance in diagram
drawing. V.A.M. would like to thank the University
of Duisburg-Essen for financial support. P.E. thanks
the Bogoliubov Laboratory of Theoretical Physics,
JINR, for the hospitality he received during his stay in
Dubna.
We investigate the interaction of correlated electrons with acoustical phonons using the extended
Hubbard–Holstein model. The Lang–Firsov canonical transformation allows one to obtain
mobile polarons for which a new diagram technique and generalized Wick’s theorem is used. The
physics of emission and absorption of the collective phonon-field mode by the polarons is discussed
in detail. In the strong-coupling limit of the electron-phonon interaction, and in the normal as
well as in the superconducting phase, chronological thermodynamical averages of products of
acoustical phonon-cloud operators can be expressed by the products of one-cloud operator averages.
While the normal one-cloud propagator has the form of a Lorentzian, the anomalous one is of
Gaussian form and considerably smaller. We have established the Mott–Hubbard and superconducting
phase transitions in this model.