Self-consistent approximation and fifth virial coefficients

Abstract

The self-consistent approximation of Rushbrooke and Hutchinson is extended so as to give consistent virial coefficients to any order by expanding the parameter Φ in terms of density, namely φ(p.T) :∗sum^∞_l-4; φ_i(T)p^l-4 By using this expansion the fifth virial coefficient was evaluated for systems of rigid spheres and for molecules obeying a Lennard-Jones 6-12 potential. The values so calculated are compared with the Percus-Yevick (PY) and the convolution hypernetted chain (CHNC) compressibility virial coefficient. The agreement appears to be good. The equation of state was calculated for hard spheres and is compared with the equation of state obtained from the PY and CHNC approximations using the virial coefficients evaluated from the compressibility equation.