Hubbard relations for linear molecules

The Hubbard relations for linear molecules in the cases of the extended diffusion model (EDM) and Ivanov's theory are derived. The M-diffusion variant of the EDM leads to an unphysical result as the dielectric and Raman correlation times approach infinity and it is suggested that M-diffusion is not a realistic model. The J-diffusion is almost the same as for spherical molecules. When the reduced angular momentum correlation time, τ _J *, is very much less than unity both EDM and Ivanov theory give a relation similar to the friction model 2], i.e. the original Hubbard relations 14] with the coefficient 6^-1, instead of 2^-1 as obtained by O'Reilly 3]. For τ _J * > 1 the various versions of Hubbard's relations are different enough to be distinguished experimentally.