Solid o-p-hydrogen: a comparison of theories of statistically disordered crystals

Mixtures of o-H2 and p-H2 or p-D2 and o-D2 respectively are model substances for theories and experiments about disordered crystals. They can be considered in parallel to dilute antiferromagnets. The spectra of librons as a function of the concentration of the ''nonmagnetic'' species (p-H2; o-D2) can be measured and calculated. Optical experiments with Raman scattering have already been performed. The k = o spectra measured in these experiments are the basis of a discussion of different approximations where the same quantity can be calculated