DOI: https://doi.org/10.30970/jps.08.223
A SELF-CONSISTENT THEORY OF LIQUID 4He
I. O. Vakarchuk
Ivan Franko National University of Lviv, Department for Theoretical Physics
12 Drahomanov St., Lviv, 79005, Ukraine
|
Journal of Physical Studies 8(3), 223–240 (2004)
DOI: https://doi.org/10.30970/jps.08.223 A SELF-CONSISTENT THEORY OF LIQUID 4HeI. O. Vakarchuk
Ivan Franko National University of Lviv, Department for Theoretical Physics |
|
A new method is proposed for the calculation of full density matrix and thermodynamic functions of a many-boson system. Explicit expressions are obtained in the pair correlations approximation for an arbitrary temperature. The theory is self-consistent in the sence that the calculated properties at low temperatures coincide with that of Bogoliubov theory and in the high-temperature limit lead to the results for classical non-ideal gas in the random phase approximation. The phase transition is also revealed as a concequence of Bose-Einstein condensation deformed by interatomic interactions. All the final formulae are written solely via the liquid structure factor taken as a source information instead of the interatomic potential and, therefore, interconnect only observable quantities. This gives also a possibility to study such a strongly non-ideal system as liquid $^4$He.
PACS number(s): 05.30.Jp, 67.20.+k, 67.40.$-$w, 67.40.Db, 67.40.Kh