Prediction of Viscosity of Liquid Alkali Metals Using an Improved Mean Spherical Approximation

In this work, the shear viscosity (η) of the liquid alkali metals including Rb, Cs, and Na is determined based on the Stokes–Einstein’s equation by an improved mean spherical approximation theory using an effective square-well potential relation for intermolecular interaction in a wide range of densities and temperatures. In this way, the PVT data and the linear isothermal regularity equation of state are used to determine the radial distribution function at a contact point at any thermodynamic state. The results obtained showed that the calculated values for viscosity increased strongly with increasing density and increased slightly with temperature. A reasonable agreement has been found between the calculated values of η and their available experimental data. Furthermore, a correlation relation between the effective molecular diameter and the temperature was found and the order of magnitude and sign of the coefficients were determined.