Condensed Matter Physics, 2010, vol. 13, No. 2, p. 23703:110
DOI:10.5488/CMP.13.23703
Title: The Bogolubov representation of the polaron model
and its completely integrable RPAapproximation
Author(s):

N.N.Bogolubov (jr.)
(Steklov Mathematical Institute of the Russian Academy of Sciences,
Moscow, Russian Federation,Abdus Salam International Centre for Theoretical Physics, Trieste, Italy)
,


Ya.A. Prykarpatsky
(Institute of Mathematics, Pedagogical University of Cracow,
Poland,Drohobych Ivan Franko State Pedagogical University, Lviv
region, Ukraine)
,


A.A. Ghazaryan
(The Lomonosov Moscow State University, Department of Physics,
Moscow, Russian Federation) 
The polaron model in ionic crystal is studied in the
Bogolubov representation using a special RPAapproximation. A
new exactly solvable approximated polaron model is derived and
described in detail. Its free energy at finite temperature is
calculated analytically. The polaron free energy in the constant
magnetic field at finite temperature is also discussed.
Based on the structure of the Bogolubov unitary transformed polaron
Hamiltonian there is stated a very important new result: the full
polaron model is exactly solvable.
Key words: polaron, polaron model, constant magnetic
field, RPAapproximation
PACS: 71.38.+i
