ROTOTRANSLATIONAL COLLISION-INDUCED ABSORPTION BY H-2-H-2 PAIRS AT TEMPERATURES FROM 600-K TO 7000-K

The computation of the far-infrared, rototranslational (RT) collision- induced absorption (CIA) spectra of H-2-H-2 pairs is presented at temp eratures from 600 to 7000 K for the first time. Theoretical results ar e based on the quantum mechanical and the semiclassical, three lowest translational spectral moments obtained for H-2 pairs. The effective, isotropic H-2-H-2 interaction potential, suitable for the high-tempera ture computations, and the ab initio induced dipoles, have been used a s input. Special effort has been made to account for the rotational an d vibrational states dependence of the dipoles, since it was found to be relevant at the high temperatures employed. The computations of the entire RT band account for all populated vibrational states of hydrog en molecule and include vibrational transitions upsilon --> upsilon' = upsilon, with upsilon = 0, 1, 2, and 3. The described method makes us e of the adequately selected model line shapes with the temperature-de pendent parameters. The presented model is useful for the ''model atmo spheres'' of zero- and low-metallicity, cool and dense stellar atmosph eres, where CIA is known to be important.