Studying structural properties of rubidium and cesium liquid metals using an effective hard-core Yukawa potential

• A modification of the RPA theory applied to the rubidium and cesium liquid metals.
• The linear isotherm regularity EOS was used to present the direct correlation function.
• Long-range interactions modeled by a pair Yukawa potential with λ = 1.8.
• Predictions for the structure factor compared with the simulation and experimental data.

In this work, we investigate the applicability of a modification of the random phase approximation (RPA) theory with an effective hard-core Yukawa potential to the static structure factor for the rubidium and cesium liquid metals. Based upon the perturbation theory, we assume that the core contribution of the direct correlation function is related to the geometric effects via a linear form for a hard-sphere fluid, in which the molecular diameter is obtained at any temperature and, its tail contribution is related to the long-range intermolecular interactions of the system via a linear form. We use the long-range Yukawa potential in the modeling of liquid alkali metals (LAMs) with the decay parameter λ = 1.8 and a well depth potential that is state-dependent. The linear isotherm regularity (LIR) equation of state (EOS) is applied to obtain the long-range interactions. The results obtained show that the proposed approach for LAMs can predict the behavior of the structure factor, S(k), at a wide range of k values with a good accuracy, as compared to the experimental data, over the whole liquid states. The interaction model used is also successful in the presentation of the Ornstein–Zernike (OZ) behavior of S(k) at the low-k region including the S(0) values.

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