Investigation of the order disorder phase transition on the basis of virial expansion

Author(s):  Yu.P. Virchenko, Belgorod National Research University, Belgorod, Russia, virch@bsu.edu.ru

L.P. Danilova, Belgorod National Research University, Belgorod, Russia

Issue:  Volume 49, №27

Rubric:  Physics. Mathematical modeling

Annotation:  The temperature critical point of the order-disorder phase transition in binary alloys is calculated. The expansion on concentration of a alloy component is applied. The construction of the expansion is reduces to the so-called virial expansion on the density of lattice gas. In order to analyze the temperature dependence of each term of the virial expansion under consideration the expansion on the order of Ursell's function in it is applied. It is shown that such a approximation method represents the modification of high temperature expansions of thermodynamic characteristics of the model. This modification permits to do the expansion convergence be more rapid. Calculation of main approximation leads to the state equation of lattice gas which is analogous , to the Van der Waals equation. It has the temperature critical point. It is expressed in terms of the interaction potential of the lattice gas atoms. Also, it is evaluated the correction to the main approximation of the critical point

Keywords:  lattice gas, critical point, interaction potential, virial expansion

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