The use of a spin-dependent intermolecular potential to predict the crystal structure and antiferromagnetism of solid α-oxygen

A spin-dependent intermolecular potential based on the overlap of molecular orbitals is proposed to describe the low-temperature $\alpha $-phase of solid oxygen. The results are compared with those of a Lennard-Jones potential calculation which gives a reasonable description of $\beta $-oxygen. The distortion of the (001) plane from hexagonal symmetry is qualitatively explained and is due to the onset of magnetic ordering at the $\beta -\alpha $ transition. The value of $J$, the magnetic exchange constant which enters phenomenological theories of magnetism, is found to be 4 K in comparison with the value of 6 K derived previously from the magnon spectrum.