Since December 2017 the set of the “TheoReTS” data sources is modified to allow more flexible access for the users by combining fast and complete spectra simulations. In general, three types of data sources could be made available for an isotopologue of an included molecule.
Full line-by-line listsFull line-by-line (LbL) linelists at low and/or room reference temperatures without quantum identification of the transition (“full_LbL_lists”).
The cut-off restrictions ( described case-by-case) permit to employ these “full_LbL_lists” within the temperatures range ( Tmin , Tmax) specified for each molecule, by an appropriate use of the T-dependence for intensities and for the partition functions.
For online simulations at the TheoReTS site, this T-dependence of spectral functions is automatically included.
“Hybrid” compressed data sources“Hybrid” compressed data sources designed for a fast spectra modeling.
For heavy molecules with low vibrational frequencies as well as for light molecules at high temperatures, the spectra could be very congested including many millions or even billions of transitions ( see , ). To accelerate a modeling of spectral functions in these cases the initially computed full LbL lists are partitioned into two sets:
(1) “Light lists” contain strong and medium transitions necessary for an accurate description of sharp features in absorption/emission spectra.
(2) For a fast and efficient modeling of quasi-continuum cross sections, billions of tiny lines are compressed in “super-lines” libraries according to .
Warning (!) : For a correct use of these “hybrid” data sources, the spectral functions computed from (1) “Light lists” and from (2) “quasi-continuum” must be summed together. Otherwise , a part of the opacity would be missing.
In case of online simulations at the TheoReTS site, both contributions from (1) and (2) data sources are automatically accounted for spectral functions. A detailed discussions and instructions for the use of “hybrid” data sources in case of high-T methane spectra can be found in .
Assigned line-by-line listsLinelists at various reference temperatures with full quantum identification of the transition: currently few limited examples – under development.
- Rey, M., Nikitin, A.V., Tyuterev, V.G. “Theoretical hot methane line lists up to t = 2000 k for astrophysical applications”. Astrophysical Journal, 789 (1), art. no. 2, (2014); doi: 10.1088/0004-637X/789/1/2.
- Rey, M., Nikitin, A.V., Tyuterev, V.G. “Accurate Theoretical Methane Line Lists in the Infrared up to 3000 K and Quasi-continuum Absorption/Emission Modeling for Astrophysical Applications”. Astrophysical Journal, 847 (2), art. no. aa8909 (2017); doi: 10.3847/1538-4357/aa8909.
- M. Rey, A.V. Nikitin, Y. Babikov, V. Tyuterev, TheoReTS - An information system for theoretical spectra based on variational predictions from molecular potential energy and dipole moment surfaces // JMS, 2016, doi:10.1016/j.jms.2016.04.006.