Soft-core mean spherical approximation

Chihara (along with Madden and Rice) extended the Percus Yevick equation for Lennard-Jones systems to provide a soft-core mean spherical approximation, the SMSA (Refs 1,2 and 3)

$B(r)=\beta \Phi _{2}(r)-\gamma (r)+\ln \left(1+\gamma (r)-\beta \Phi _{2}(r)\right)$

References

1. [PTP_1973_050_0409]
2. [PTP_1973_050_1156]
3. William G. Madden and Stuart A. Rice "The mean spherical approximation and effective pair potentials in liquids", Journal of Chemical Physics 72 pp. 4208-4215 (1980)