Journal of Physical Studies 11(3), 259–267 (2007)
DOI: https://doi.org/10.30970/jps.11.259

## KINETIC ENERGY AND HEAT CAPACITY OF LIQUID 4He

I. O. Vakarchuk, R. O. Prytula, A. A. Rovenchak

Ivan Franko National University of Lviv, Department for Theoretical Physics,
12 Drahomanov St., Lviv, UA–79005, Ukraine

A new method is proposed for the description of the thermodynamic properties of liquid helium-4 in a wide temperature range, including $λ$-transition. The density matrix of interacting Bose-particles is used in the approximation of pair correlations [I. O. Vakarchuk, J. Phys. Stud. {\bf 8}, 223 (2004)]. We obtained the expressions for the kinetic and potential energy and also for the pair structure factor. All the final formulae are written solely via the liquid structure factor extrapolated to $T=0$ taken as a source information instead of the interatomic potential. We calculated the dependence on temperature for the kinetic and potential energy, pair structure factor, and heat capacity. In the domain of low temperatures $01$ our results reproduce the course of experimental data qualitatively (the calculated curve is shifted up almost parallelly).

PACS number(s): 05.30.Jp, 67.20.+k, 67.40.-w, 67.40.Db, 67.40.Kh