Simple perturbation method for convex‐molecule fluids

The second‐order perturbation theory of convex‐molecule fluids with pair interactions of the generalized Kihara type is considered. The double Yukawa potential function and the Laplace transform of the hard‐sphere correlation function in the PY approximation are used to evaluate a part of the perturbation integral. The perturbation theory was applied to model systems of the LJ molecules and Kihara rod‐like particles; calculated thermodynamic functions agree well with the corresponding Monte Carlo data and results from the Weeks–Chandler–Andersen theory. Characteristic parameters of several fluids with spherical and rod‐like molecules were evaluated from the saturated liquid properties. Comparison with the corresponding parameters of the multicenter LJ potential is given.

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