where Φ ( r n m ) {\displaystyle \Phi (r_{nm})} is the intermolecular pair potential, T is the temperature, and k B {\displaystyle k_{B}} is the Boltzmann constant.
![{\displaystyle k_{B}T{\frac {\partial \ln {\rm {g}}(r_{12})}{\partial {\mathbf {r} }_{1}}}={\frac {-\partial \Phi (r_{12})}{\partial {\mathbf {r} }_{1}}}-\rho \int \left[{\frac {\partial \Phi (r_{13})}{\partial {\mathbf {r} }_{1}}}\right]{\rm {g}}(r_{13}){\rm {g}}(r_{23})~{\rm {d}}{\mathbf {r} }_{3}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d3a7d316a708e5b2aaaf57f0c335adb93f09c2d1)
