Square-Well Potential. I. An Yvon-Born-Green Square-Well Equation of State

The Yvon‐Born‐Green integral equation for the pair correlation function is solved for the square‐well potential with ${\sigma }_2{\mathrm{/\sigma }}_1\text{=1.85}$ , using a $\mathrm{\theta =\epsilon /kT}$ expansion scheme previously devised by Kirkwood et al. The pertinent results are expressed in a power series of density by a least squares technique for the entire gas and liquid regimes. The coexistence region is determined, including the location of the critical point, and thermodynamic properties are calculated and tabulated as functions of state. The validity and utility of the results are examined in detail.