Formation of Dimers in Polar Gases: Contribution of Metastably Bound Molecules to the Second Virial Coefficient

Abstract

The contribution of metastably bound double molecules to the second virial coefficient B(T) of a polar gas has been calculated by assuming the dipoles to be in the head-to-tail position. The same results can also be applied for any ‘effective’ relative orientation of the dipoles. The percentage of dimers has been calculated from the contribution of bound and metastably bound double molecules to the second virial coefficient for NH₃ and CHCl₃. The results have been compared with those obtained from the semiempirical approach of Hirschfelder, McClure and Weeks.