ZhETF, Vol. 141,
No. 2,
p. 355 (February 2012)
(English translation  JETP,
Vol. 114, No. 2,
p. 314,
February 2012
available online at www.springer.com
)
THERMODYNAMICS OF AN INTERACTING FERMI SYSTEM IN THE STATIC FLUCTUATION APPROXIMATION
Nigmatullin R.R., Khamzin A.A., Popov I.I.
Received: April 19, 2011
We suggest a new method of calculation of the equilibrium correlation functions of an arbitrary order for the interacting Fermigas model in the framework of the static fluctuation approximation method. This method based only on a single and controllable approximation allows obtaining the socalled fardistance equations. These equations connecting the quantum states of a Fermi particle with variables of the local field operator contain all necessary information related to the calculation of the desired correlation functions and basic thermodynamic parameters of the manybody system. The basic expressions for the mean energy and heat capacity for the electron gas at low temperatures in the highdensity limit were obtained. All expressions are given in the units of r_{s}, where r_{s} determines the ratio of a mean distance between electrons to the Bohr radius a_{0}. In these expressions, we calculate terms of the respective order r_{s} and r^{2}_{s}. It is also shown that the static fluctuation approximation allows finding the terms related to higher orders of the decomposition with respect to the parameter r_{s}.

