<p> An intermolecular potential between two diatomic molecules consisting of quadrupole, dispersion and repulsive terms has been used to determine the librational modes of the molecules in the solid α phase. Fixed centers of mass of the molecules, i.e. no translational motion has been assumed and the calculation is carried out in the small angle approximation for both N2 and CO. The calculated modes of nitrogen are used to study the temperature dependence of the nuclear quadrupole resonance frequency. The results are compared with Raman scattering and N.Q.R. experiments. An alternate approximation is included in the discussion.</p> / Thesis / Master of Science (MSc)