Condensed Matter Physics, 2015, vol. 18, No. 4, 43005
DOI:10.5488/CMP.18.43005
arXiv:1503.02428
Title:
The selfconsistent field model for Fermi systems with account of threebody interactions
Author(s):

Yu.M. Poluektov
(Akhiezer Institute for Theoretical Physics, National Science Center ``Kharkiv Institute of Physics and Technology'', 1 Akademichna St., 61108 Kharkiv, Ukraine)
,


A.A. Soroka
(Akhiezer Institute for Theoretical Physics, National Science Center ``Kharkiv Institute of Physics and Technology'', 1 Akademichna St., 61108 Kharkiv, Ukraine)
,


S.N. Shulga
(Akhiezer Institute for Theoretical Physics, National Science Center ``Kharkiv Institute of Physics and Technology'', 1 Akademichna St., 61108 Kharkiv, Ukraine)

On the basis of a microscopic model of selfconsistent field, the thermodynamics of the manyparticle Fermi system at finite temperatures with account of threebody interactions is built and the quasiparticle equations of motion are obtained. It is shown that the deltalike threebody interaction gives no contribution into the selfconsistent field, and the description of threebody forces requires their nonlocality to be taken into account. The spatially uniform system is considered in detail, and on the basis of the developed microscopic approach general formulas are derived for the fermion's effective mass and the system's equation of state with account of contribution from threebody forces. The effective mass and pressure are numerically calculated for the potential of ``semitransparent sphere'' type at zero temperature. Expansions of the effective mass and pressure in powers of density are obtained. It is shown that, with account of only pair forces, the interaction of repulsive character reduces the quasiparticle effective mass relative to the mass of a free particle, and the attractive interaction raises the effective mass. The question of thermodynamic stability of the Fermi system is considered and the threebody repulsive interaction is shown to extend the region of stability of the system with the interparticle pair attraction. The quasiparticle energy spectrum is calculated with account of threebody forces.
Key words:
selfconsistent field, threebody interactions, effective mass, fermion, equation of state
PACS:
05.30.Ch, 05.30.Fk, 05.70.a
