Half of the product of the stress of attraction or repulsion by the distance between two particles
The quantity 1/2 Rr, or half the product of the attraction into the distance across which the attraction is exerted, is defined by Clausis as the virial of the attraction. (In the case of pressure or repulsion, the virial is negative.).
A certain function relating to a system of forces and their points of application, first used by Clausius in the investigation of problems in molecular physics