Perturbation Theory and the Radial Distribution Function of the Square-Well Fluid

Abstract

Perturbation theory is used to derive the first‐order term of the inverse temperature expansion of the radial distribution function (RDF) for a fluid whose molecules have a hard core. Exact and approximate expressions, based on the local compressibility approximation, the superposition approximation (SA), and the Percus‐Yevick theory (PY) are derived. Numerical results are examined in the case of the square‐well potential with wellwidth 0.50. The RDF resulting from the exact and SA expression yield good results for the equation of state down to reduced temperatures below $\text{β ε=1}$ .