Coupling-parameter expansion in thermodynamic perturbation theory.

A Sai Venkata Ramana, S V G Menon

Theoretical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.

Physical review. E, Statistical, nonlinear, and soft matter physics 2013 Feb

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An approach to the coupling-parameter expansion in the liquid state theory of simple fluids is presented by combining the ideas of thermodynamic perturbation theory and integral equation theories. This hybrid scheme avoids the problems of the latter in the two phase region. A method to compute the perturbation series to any arbitrary order is developed and applied to square well fluids. Apart from the Helmholtz free energy, the method also gives the radial distribution function and the direct correlation function of the perturbed system. The theory is applied for square well fluids of variable ranges and compared with simulation data. While the convergence of perturbation series and the overall performance of the theory is good, improvements are needed for potentials with shorter ranges. Possible directions for further developments in the coupling-parameter expansion are indicated.

Citation

A Sai Venkata Ramana, S V G Menon. Coupling-parameter expansion in thermodynamic perturbation theory. Physical review. E, Statistical, nonlinear, and soft matter physics. 2013 Feb;87(2):022101