Cavity correlation function

The cavity correlation function, $y(r_{12})$, is given by

$y(r)\equiv \mathrm{g}(r)/e^{-\beta {\mathrm{\Phi }}_{12}(r)}$

where $g(r)$ is the pair distribution function, ${\mathrm{\Phi }}_{12}(r)$ is the pair potential, and $\beta :=1(/k_{B}T)$, where $k_B$ is the Boltzmann constant and $T$ is the temperature.