A new volume dependence for the equations of state of hard spheres

Most equations of state for hard spheres proposed in literature fail to satisfy the close-packed limit and predict a finite value for compressibility factor at the close-packing state. In this work we propose a new volume dependence for equations of state for hard spheres which meets both the low density and the close-packed limits of the compressibility factor. The new form of volume dependence is used to modify previously proposed equations of state for hard spheres. The results obtained show that, without sacrificing the precision in the low density region, the new equations of state can correlate better the computer generated values of compressibility factor up to high densities. The phenomenon of the plastification of hard spheres at high densities, and its relation to the determination of the parameters of the equations of state for hard spheres, is also discussed.