Modeling of collision-induced infrared absorption spectra of H \u3c inf\u3e 2 -H \u3c inf\u3e 2 pairs in the fundamental band at temperatures from 20 to 300 K

A numerical method is presented which generates the rotovibrational (free-free) collision-induced absorption (RV CIA) spectra of H2-H2 pairs in the fundamental band of hydrogen, at temperatures from 20 to 300 K. Computed synthesized spectra are found to be in close agreement with all presently known CIA spectra of H2-H2 and reproduce the results of the quantum mechanical computations to within a few percent. The spectral lineshape parameters are obtained from the lowest three quantum mechanical spectral moments computed from first principles. The model RV CIA spectra of H2-H2 can thus be computed easily even on small computers. The work is of interest for the modeling of the atmospheres of the outer planets in the near infrared region of the spectrum. © 1991