Analytic Calculation of the Critical Temperature and Estimation of the Critical Region Size for a Fluid Model


  • I.V. Pylyuk Institute for Condensed Matter Physics, Nat. Acad. of Sci. of Ukraine
  • M.P. Kozlovskii Institute for Condensed Matter Physics, Nat. Acad. of Sci. of Ukraine
  • O.A. Dobush Institute for Condensed Matter Physics, Nat. Acad. of Sci. of Ukraine



cell fluid model, Morse interaction potential, grand partition function, recurrence relations, critical temperature, critical region


An analytic procedure for calculating the critical temperature and estimating the size of the critical region for a cell fluid model is developed. Our numerical calculations are illustrated by the case of the Morse potential parameters characterizing the alkali metals (sodium and potassium). The critical temperatures found for liquid sodium and potassium as solutions of the resulting quadratic equation agree with experimental data. The expression for the relative temperature determining the critical region size is obtained proceeding from the condition for the critical regime existence. In the cases of sodium and potassium, the value of this temperature is of the order of a few hundredths.


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How to Cite

Pylyuk, I., Kozlovskii, M., & Dobush, O. (2023). Analytic Calculation of the Critical Temperature and Estimation of the Critical Region Size for a Fluid Model. Ukrainian Journal of Physics, 68(9), 601.



Physics of liquids and liquid systems, biophysics and medical physics