HMSA

The hybrid mean spherical approximation (HMSA) smoothly interpolates between the HNC and the mean spherical approximation closures

$g(r)=\exp(-\beta u_{r}(r))\left(1+{\frac {\exp[f(r)(h(r)-c(r)-\beta u_{a}(r))]-1}{f(r)}}\right)$

where $g(r)$ is the radial distribution function.