The influence of anharmonic and magnetic interactions on lattice dynamics of α and β phases of solid oxygen

The lattice dynamics of the ordered phases of solid oxygen have been studied. The anharmonic shifts for the librational excitations have been calculated. The comparison of harmonic and anharmonic results has shown that anharmonic effects in, solid oxygen are very important. An analysis of the influence of the magnetic ordering in the antiferromagnetic α phase suggest that magnetic interactions and elastic deformation of the crystal unit cell can compensate each other and lead to the accidental degeneration of the A_s and B_s librational energies in the α phase.