Direct determination of the intermolecular potential for H-2-H-2 from a viscosity correlation equation

A correlation equation for the low-density viscosity collision integral of hydrogen molecules over a very large temperature range is obtained. This eq uation has been inverted directly to give the reduced intermolecular potent ial energy curve for H-2-H-2 corresponding to the collision integral. The r esults are then used to obtain a best Morse-Spline-Van der Waals (MSV) pote ntial model. Comparison is made between the present interaction potential e nergy function and two other previously published H-2-H-2 potential energy functions. The present potential function provides the best overall agreeme nt for the available low-density gas phase thermophysical data, i.e. second virial coefficient and transport properties, and can thus be recommended f or calculation of all properties that depend upon the intermolecular intera ction.