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Journal of Physical Studies 5(3/4), 221–232 (2001)
DOI: https://doi.org/10.30970/jps.05.221 THERMODYNAMIC CHARACTERISTICS OF THREE-DIMENSIONAL ISING-LIKE SYSTEMS AS FUNCTIONS OF MICROSCOPIC PARAMETERS. THE ρ6 MODEL APPROXIMATIONI. V. Pylyuk
Institute for Condensed Matter Physics
of the National Academy of Sciences of Ukraine |
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The microscopic approach to calculating and investigating the three-dimensional (3D) Ising-like system thermodynamics above and below the phase transition temperature $T_c$ is developed using the collective variables method. Mathematical description is performed within the framework of the higher non-Gaussian approximation ($ρ^6$ model) taking into account the corrections to scaling. A nonuniversal factor depending on microscopic parameters of the system is singled out in the expressions for leading critical amplitudes and correction-to-scaling amplitudes. Numerical estimates of the critical region size, phase transition temperature as well as the graphs of temperature dependences of entropy and other thermodynamic characteristics near $T_c$ are given for various values of effective radius of the exponentially decreasing interaction potential. The variation of the free energy of the system at the phase transition point, average spin moment, and specific heat with increasing ratio of the potential effective radius to the simple cubic lattice constant is traced. The results of calculations and their comparison with the other authors' data show that the $ρ^6$ model provides a more adequate quantitative description of the critical behaviour of a 3D Ising-like system than the $ρ^4$ model.
PACS number(s): 05.50.+q, 05.70.Ce, 64.60.Fr, 75.10.Hk