Thermodynamic feature of Bose fluid evaluated from formulations for a quasiparticle system with anisotropy

Formulations for estimating thermodynamic quantities from the free energy of a quasiparticle system involving anisotropy reveal the fact that a specific temperature at which the anisotropy is lost from the system depends on Δ̂, that is, one of the important parameters characterizing the quasiparticle system. Evaluating the thermodynamic contribution from the derived formulas should assist in the evaluation of the contribution from particles that should move collectively with momenta, each of which has a magnitude smaller than a specific value. When the temperature T of a Bose fluid system is increased toward a specific value Tc, at which the absolute value of the chemical potential becomes equal to the magnitude of the mean effect of attractive forces acting between a single particle and the surrounding particles, the contribution from quasiparticles to the specific heat CV allows the magnitude of CV to increase steeply. After CV reaches a maximum at T = Tc, increasing T causes it to decrease steeply. The CV behavior implies that Tc can be approximated as the temperature below which the anisotropic effect appears. Evaluating the contribution of quasiparticles aids in determining the thermodynamic quantity of the Bose fluid system in a quasiclassical manner.