Linear hard sphere models Virial coefficients and equation of state

Abstract

Virial coefficients of tangent hard spheres in a linear configuration have been determined numerically. Trends of the virial coefficients with the molecular anisotropy are similar to those of other linear models, such as hard spherocylinders or hard ellipsoids. Theoretical predictions of virial coefficients from different equations of state of hard body fluids are compared with the numerical results. None of them provides a completely satisfactory description of the lower virial coefficients when the anisotropy of the molecule is large. We propose a new method to build up an equation of state of hard linear models (prolate or oblate) from the knowledge of the first five virial coefficients. The equation of state obtained in this way provides a very good description of the equation of state of hard linear fluids at low, medium and high anisotropies.