Rovenchak A. A self-consistent calculation of interatomic potentials and thermodynamic functions of helium-4 in superfluid and normal phase

The study of a strongly-interacting Bose-system with helium-4 as an example is carried out in a wide temperature region. The collective variables formalism, two-time temperature Green's functions techniques, as well as the 1/N-expansion are utilized. The pair and three-body interatomic potentials are determined. A self-consistent method for the calculation of thermodynamic functions is proposed/ This method takes into account the corrections to the random phase approximation in a n effective manner. A good agreement with experiment is achieved in the superfluid and normal phases. The question of helium-4 atom effective mass is considered. The condensate fraction at T = 0 К is estimated as 11%. The results are used in the educational process, in scientific work. Application realm is the theory of interacting quantum systems.