SIMBAD references

A new line list for ethylene, ¹²C₂¹H₄, is presented. The line list is based on high-level ab initio potential energy and dipole moment surfaces. The potential energy surface is refined by fitting to experimental energies. The line list covers the range up to 7000 cm^–1 (1.43 µm) with all ro-vibrational transitions (50 billion) with the lower state below 5000 cm^–1 included and thus should be applicable for temperatures up to 700 K. A technique for computing molecular opacities from vibrational band intensities is proposed and used to provide temperature-dependent cross-sections of ethylene for shorter wavelength and higher temperatures. When combined with realistic band profiles (such as the proposed three-band model), the vibrational intensity technique offers a cheap but reasonably accurate alternative to the full ro-vibrational calculations at high temperatures and should be reliable for representing molecular opacities. The C₂H₄ line list, which is called MaYTY, is made available in electronic form from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) databases.