Perturbation theory using the Yvon–Born–Green equation of state for square-well fluids

Abstract

Using the Yvon−Born−Green integral equation with superposition approximation for the square−well potential with R=σ₂/σ₁=1.5, values of the coefficients of the reciprocal temperature expansion of the Helmholtz energy are computed. The results compare favorably up to values of n*=0.7 with the machine computations of Alder, Young, and Mark through A₄/NkT despite obvious differences in the hard−sphere reference pair correlation functions between the two approaches.