Renormalized interactions in solid hydrogen and analysis of the ortho-pair level structure

Abstract

The orientational level structure of o-H2 pairs in a solid p-H2 matrix is studied theoretically, with particular attention paid to the phonon renormalization of the anisotropic interactions. For the two- and three-body multipolar and induction forces, this renormalization is performed analytically and the results are expressed in terms of a small number of lattice dynamical parameters describing the shape of the anisotropic distribution function, g(u12), of the relative zero-point displacement of a pair of molecules. A microscopic calculation of these parameters has revealed that the difficulties remaining in the theoretical analysis carried out by Harris, Berlinsky, and Hardy of the microwave spectra observed by Hardy, Berlinsky, and Harris stem from an incorrect parametrization of the deviations of g(u12) from cylindrical symmetry. Using our renormalization results, as well as a more convenient symmetry classification of the effective interactions in the solid, we arrive at an analysis of the microwave spectra which appears to be free of difficulties. From this analysis we obtain the following values of the effective anisotropic interaction constants in solid H2 at normal pressure: the quadrupolar coupling constant [Formula: see text] and the van der Waals coupling constants [Formula: see text], [Formula: see text], and [Formula: see text].