A. A. Rovenchak
Ivan Franko National University of Lviv, Department for Theoretical Physics,
12 Drahomanov Str., Lviv, UA--79005, Ukraine
The calculation of the \He4 energy and specific heat is carried out in a wide temperature range within the two-time temperature Green functions approach. The approximation improving the random phase approximation is developed providing the correct behaviour of the calculated specific heat at the temperatures $0 < T/T_c < 0.65$ and $T/T_c> 1.32$ where $T_c$ stands for the phase transition point.
PACS number(s): 05.70.Ce, 67.20.+k, 67.40.$-$w