On the Kinetic Theory of Dense Fluids. VII. The Doublet Distribution Function for Rigid Spheres with an Attractive Potential

A new integro-differential equation for the doublet distribution function of a model dense fluid is derived and solved. In this model, the intermolecular pair potential is represented as a rigid core plus an attraction. Interactions involving rigid cores are handled as in the theory of the dense rigid-sphere fluid and attractive interactions are handled as in the Fokker-Planck theory. The resultant doublet distribution function is compared with the singlet distribution function calculated for the same model.