### Theoretical line lists of methane at T=80, 296, 500, 1000, 1500 and 2000K

All theoretical methane line lists included in TheoReTS are calculated by the variational method (except for "mixed abinitio/effective" model, see below # ))

from the following

*ab initio*based potential energy surface (PES) and dipole moment surfaces (DMS):

NRT PES-2011:

A.Nikitin, M.Rey, and Vl.G.Tyuterev , Rotational and vibrational energy levels of methane calculated from a new potential energy surface,

*Chemical Physics Letters*, 501, Issues 4-6, pp 179-186 (2011)

Ab initio DMS was defined in the same format as NRT DMS-2013 ( A.V. Nikitin, M. Rey, Vl.G. Tyuterev, New dipole moment surfaces of methane,

*Chem. Phys. Lett.*, 565, 5–11 (2013)) but was recently improved using larger electronic basis set ( to be submitted)

Techniques of variational calculations are decribed in

Rey, M.; Nikitin, A. V., and Tyuterev, Vl. G. First-principles intensity calculations for the methane rovibrational spectra in the infrared up to 9300 cm

^{-1}.

*Phys. Chem. Chem. Phys.*,

*15*, 10049-10061 (2013)

Rey, M.; Nikitin, A. V., and Tyuterev, Vl. G. Predictions for methane spectra from potential energy and dipole moment surfaces: isotopic shifts and comparative study of

^{13}CH

_{4}and

^{12}CH

_{4}.

*J.Mol.Spectroscopy*, 291, 85-97 (2013).

M. Rey, A.V. Nikitin and Vl. G. Tyuterev, "Accurate first-principles calculations for CH

_{3}D infrared spectra from isotopic and symmetry transformations",

*J. Chem. Phys*., 141 (2014) 044316

M. Rey, A.V. Nikitin, and Vl. G. Tyuterev , First predictions of rotationally resolved infrared spectra of Di-deuteromethane

^{12}CH

_{2}D

_{2}from potential energy and dipole moment surfaces

*, J.Phys . Chem. A*, 119, 4763−4779 (2015)

M. Rey, A.V. Nikitin, and Vl. G. Tyuterev, Convergence of normal mode variational calculations of methane spectra: Theoretical linelist in the icosad range computed from potential energy and dipole moment surfaces,

*Journal of Quantitative Spectroscopy & Radiative Transfer*164 (2015) 207–220.

High-T line lists were calculated using the same approach as described in:

M. Rey, A.V. Nikitin and Vl. G. Tyuterev, "Theoretical hot methane line list up to 2000 K",

*Astrophysical Journal*, 789 (2014) 1

but were further improved in TheoReTS using larger vibrational basis sets and higher reduction scheme.

Simulations of absorption/emission spectra and XS (

*Spectra simulation*section ) for high-T using full-suze data use the "Super-lines" compression technique

as discribed in

Rey, M.; Nikitin, A. V.; and Tyuterev, Vl. G, "TheoReTS - An information system for theoretical spectra based on variational predictions from molecular potential energy and dipole moment surfaces",

*J.Mol.Spectrosc.*, to be published (2016)

The partition Q(T) function was calculated as described in

Nikitin A.V., Krishna B.M., Rey M, Tashkun S.A., and Tyuterev VlG. Methane high- temperature partition function from contact transformations and variational calculations. J Quant Spectrosc Radiat Transfer 2015;167:53–63.

#)

*High-resolution line lists*in the Dyad and Pentad randes of 12CH4 were obtained with "

*mixed abinitio/effective*" model as described in

Vl.G. Tyuterev, S.A. Tashkun, M. Rey, R.V. Kochanov, A.V. Nikitin. , and T.Delahaye, Accurate spectroscopic models for methane polyads derived from a potential energy surface using high-order Contact Transformations.

*J. Phys. Chem. A*.,117, 13779-13805 (2013)

using MOL_CT program suite. This new polyad model derived from the NRT PES permitted generating a spectral line lists for the Dyad and

Pentad bands with the accuracy 10-3 - 10-4 cm-1 for line positions combined with ab initio predictions for line intensities.