1. Calculated molecular line lists for the opacity of exoplanets, cool stars and other hot atmospheres
Jonathan Tennyson, Sergei Yurchenko and
Oleg Polyansky
Physics and Astronomy
University College London
Urbana
June 2016
Image credit Shutterstock

2. @ExoMol CO2 ScH, TiH H2O,H3+ NH3 HCN H2O2 CO2 CrH NaCl, KCl C2H4 SO3
HNO3
NH3 C3
NH3
CH4
VO, TiO
HCCH
PH3
H2CO
HOOH
@ExoMol

3. J Tennyson and S.N. Yurchenko, MNRAS, 425, 21 (2012).
5 year project from May 2011
Provide data for all molecular transitions important for exoplanet atmospheres
Methodology: first principles quantum mechanical calculations, informed by experiment
J Tennyson and S.N. Yurchenko, MNRAS, 425, 21 (2012).

4. UNCORRECTED PROOF Journal of Molecular Spectroscopy
Journal of Molecular Spectroscopy xxx (2016) xxx-xxx
Contents lists available at ScienceDirect
Journal of Molecular Spectroscopy
journal homepage:
The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres
Jonathan Tennyson,⁎ Sergei N. Yurchenko, Ahmed F. Al-Refaie, Emma J. Barton, Katy L. Chubb, Phillip A. Coles,
S. Diamantopoulou, Maire N. Gorman, Christian Hill, Aden Z. Lam, Lorenzo Lodi, Laura K. McKemmish, Yueqi Na, Alec Owens, Oleg L. Polyansky, Clara Sousa-Silva, Daniel S. Underwood, Andrey Yachmenev, Emil Zak
Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
A R T I C L E I N F O
A B S T R A C T
Article history:
Received 16 December 2015
Received in revised form 10 May Accepted 12 May 2016
Available online xxx
The ExoMol database ( provides extensive line lists of molecular transitions which are valid over ex- tended temperatures ranges. The status of the current release of the database is reviewed and a new data structure is speci- fied. This structure augments the provision of energy levels (and hence transition frequencies) and Einstein A coefficients with other key properties, including lifetimes of individual states, temperature-dependent cooling functions, Landé g-fac-
tors, partition functions, cross sections, k-coefficients and transition dipoles with phase relations. Particular attention is paid to the treatment of pressure broadening parameters. The new data structure includes a definition file which provides the necessary information for utilities accessing ExoMol through its application programming interface (API). Prospects for the inclusion of new species into the database are discussed.
© 2016 Published by Elsevier Ltd.
Keywords: Infrared Visible
Einstein A coefficients Transition frequencies Partition functions Cooling functions Lifetimes
Cross sections k coefficients Landé g-factors
UNCORRECTED PROOF
1. Introduction
are extremely rich in structure with hundreds of thousands to many billions of spectral lines which may be broadened by high-pressure and temperature effects.
The ExoMol project [19] aims to provide the molecular line lists that astronomers need in order to understand the physics and chem- istry of astronomical bodies cool enough to form molecules in their at- mospheres. In particular for extrasolar planets, brown dwarfs and cool stars [2,3,20], as well as circumstellar structures such as planetary en- velopes and molspheres [21]. In practice these data are also useful for a wide range of other scientific disciplines; examples include studies of the Earth’s atmosphere [22,23], hypersonic non-equilibrium [24],
analysis of laboratory spectra [25–27], measurements of hot reactive gases [28] and the proposed remote analysis of molecular composition using laser oblation [29].
The original ExoMol data structure was very focused in its goal, with the scope of the data limited to generating lists of transitions [30]. However, it has become obvious that the potential applications of the ExoMol spectroscopic data are much more diverse. For ex- ample, the ExoMol data can be used to compute partition functions [31], cross sections [32], lifetimes [33], Landé g-factors [34] and other
properties. Our aim is to systematically provide this additional data to maximize its usefulness. To do this requires significant extension of the ExoMol data structure, which is the major purpose of this paper. At the same time this implementation should facilitate the adoption of an application programming interface (API) between the database and programs using it. Similar enhancements are actively being pur- sued by other related databases such as HITRAN [35–37]. A major new feature is the inclusion, albeit at a fairly crude level, of pressure-
Hot molecules exist in many environments in space including cool stars [1], failed stars generally known as brown dwarfs [2,1] and exo- planets [3]. The atmospheric properties of these objects are known to be strongly influenced by the spectra of the molecules they contain. On Earth, spectra of hot molecules are observed in flames [4,5], dis- charge plasmas [6,7], explosions [8] and in the hot gases emitted, for example, from smoke stacks [9]. In addition, high-lying states can be important in non local thermodynamic equilibrium (non-LTE) envi- ronments both in space, for example, emissions observed from comets [10,11], and on Earth. The spectra of key atmospheric molecules at room temperature have been the subject of systematically maintained databases such as HITRAN [12–14] and GEISA [15,16]. As will be
amply illustrated below, the spectra of hot molecules contain many, many more transitions and so far attempts to compile systematic data- bases have been limited. Databases of hot molecular spectra do ex- ist for other specialized applications, such as the EM2C database for combustion applications [17] or one due to Parigger et al. for studies of laser-induced plasmas [18].
Planets and cool stars share some common fundamental charac- teristics: they are faint, their radiation peaks in the infrared and their atmosphere is dominated by strong molecular absorbers. Modelling planetary and stellar atmospheres is therefore difficult as their spectra
⁎ Corresponding author.
address: (J. Tennyson)
/© 2016 Published by Elsevier Ltd.

5. @ExoMol CO2 ScH, TiH H2O,H3+ NH3 HCN H2O2 CO2 CrH NaCl, KCl C2H4 SO3
HNO3
NH3 C3
NH3
CH4
VO, TiO
HCCH
PH3
H2CO
HOOH
@ExoMol
Sergei is responsible for most molecules. Story. Instead of decorating his chest with all, just these three most important ones.

6. DATABASES HITRAN (atmospheric gases)
Room temperature, mostly experiment
GEISA (room T)
Typically lines per molecule
EXOMOL
(Molecular spectroscopy in search of life and intelligence in our Galaxy- biomarkers and industrial polutants)
Hot T , mostly theory (with some exp input), typically few billions of lines

7. The Exoplanet Revolution
9 to > 3400 in 20 years!
We have come a long way since 18 years…
SSTL - July 2014

8. Courtesy of Kepler’s team

10. Radial velocity / Occultation
HD b
Period = 3.52 days
Mass = 0.69 ±0.05 MJupiter
Radius = 1.35 ±0.04 RJupiter
Density = 0.35 ±0.05 g/cm3
Drop of brightness of the star 10

11. Exoplanets

12. HD189733b: Primary transit with Spitzer
Beaulieu et al., 2007
Knutson et al., 2007 12

13. Tinetti et al., Nature, 448, 163 (2007)‏
Water line list: BT2
Barber et al., 2006
Water, different T-P
Tinetti et al., Nature, 448, 163 (2007)‏ 13

14. Water,methane and hazes!
Pont et al., 2007
Swain et al., 2008
Knutson et al., 2007
Beaulieu et al., 2007
Confirmation of
Water,methane and hazes!
Swain MR,Vasisht G and Tinetti G,
Nature, v.452,329(2008) 14

15. First detection of super-Earth atmosphere
Exoplanet 55 Cancri e has a dry atmosphere without any indications of water vapor.
HCN detected!
“Hydrogen cyanide, or prussic acid, is highly poisonous, so it is perhaps not a
planet I would like to live on!”
J. Tennyson, UCL press release
A. Tsiaras, M. Rocchetto, I.P. Waldmann, G. Tinetti, R. Varley, G. Morello, E.J. Barton, S.N. Yurchenko & J. Tennyson, Astrophys. J. v.820,99 (2016)

16. Frontier Problems in Exoplanet Characterization
Non-equilibrium processes in exoplanet atmospheres
(Stevenson et al. 2010; Madhusudhan & Seager 2011; Moses et al. 2013) CH4, CO, NH3
Constraints on thermal inversions in hot Jupiters
(Fortney et al. 2008; Spiegel et al. 2009) TiO, VO, H2S
C/O ratios and Carbon-rich atmospheres
(Fortney et al. 2008; Spiegel et al. 2009) H2O, CO, HCN, CH4,
C2H2,TiH, FeH
Constraints on exoplanet formation conditions
(Madhusudhan et al. 2011; Oberg et al. 2011) H2O, CO, CH4
Atmospheres and interiors of super-Earths
(Bean et al. 2011; Desert et al. 2011; Miller-Ricci Kempton et al ) H2O, CO2
Frontier Problems in Exoplanet Characterization
Polish this slide. Order the points properly, etc..
Slide courtesy of N Madhusudhan (Cambridge)

17. Molecular line lists for exoplanet & other atmospheres
list of molecules
Molecular line lists for exoplanet & other atmospheres
Primordial (Metal-poor)
Terrestrial Planets (Oxidising)
Giant-Planets & Cool Stars
(Reducing atmospheres)
Already available
H2, LiH
HeH+, H3+
H2D+
OH, CO2, O3, NO
H2O, HDO, NH3
H2, CN, CH, CO, CO2, TiO
HCN/HNC, H2O, NH3,
ExoMol
O2, CH4, SO2, SO3
HOOH, H2CO, HNO3
CH4, PH3, C2, C3, HCCH, H2S, C2H6, C3H8, VO, O2, AlO, MgO, CrH, MgH, FeH, CaH, AlH, SiH, TiH, NiH, BeH, YO
Available from elsewhere
Already calculated at UCL
Will be calculated during the ExoMol project
Full details:
J. Tennyson and S.N. Yurchenko, MNRAS, 425, 21 (2012)

18. Hot line lists Published in MNRAS BeH, MgH, CaH SiO HCN/HNC CH4
NaCl, KCl PN
PH3
H2CO
AlO
NaH
HNO3 CS
CaO
SO2
H2O2
H2S
SO3 VO
H3+
(Virtually) Complete
SH, AlH
H216O (global)
H217O (global)
H218O (global)
HDO (global)
NO, NS
CrH
Planned
MgO
NiH
FeH
Larger
hydrocarbons
In progress
TiO C3
PH, PO, PS
TiH
MnH
NaO
C2H4
SiH
HCCH
CH3Cl
HCN/HNC(global)
SiH4
NH3 (global)

19. Completeness and Accuracy
1. All molecules
High v (towards optics and UV) (high T)
High J (towards high T)
cm-1 (line position) and 0.3% (Intensity)-ideal
5 cm-1 , 20% - upper bound of accuracy, acceptable for some astrophysical applications

20. Completeness: Absorption of ammonia (T=300 K)
BYTe
Less than 30,000 NH3 lines are known experimentally: our list contains 1.1 billion lines, or about 40,000 times as many! They represent all the allowed transitions between 1.2 million upper and lower ro-vibrational states, whose individual quantum numbers are detailed in the list. For comparison, it is worth noting that our earlier T=300 K NH3 line list comprises only 3.25 million transitions between 184,400 states. It has an upper energy cut-off of 12,000 cm-1 and a maximum rotational quantum number J=20.
Less than 30,000 NH3 lines known experimentally:
BYTe contains 1.1 billion lines, about 40,000 times as many!
S.N. Yurchenko, R.J. Barber & J. Tennyson, Mon. Not. R. astr. Soc., 413, 1828 (2011) 20

21. Method: Spectrum from the “first-principles”
Ab initio calculations
DMS
PES
Variational calculations
Rovibrational
wavefunctions
energies
Intensities (Einstein Aif)
Line list
Refinement 21

22. Ab initio – MOLPRO Nuclear motion: DUO- 2-atomics DVR3D – 3-atomics TROVE-4,5-atomics
DUO - Yurchenko S , Lodi L., Tennyson J, Stolyarov A , Comp. Phys. Comm, v.202, p. 262 (2016)
DVR3D –Tennyson, J Kostin M, Barletta P, Harris G, Polyansky O.,et al
Comp.Phys.Comm., v.163,pp (2004)
TROVE - Yurchenko S. N. , Thiel W., Jensen P.
Theoretical ROVibrational Energies (TROVE): A robust numerical approach to the calculation of rovibrational energies for polyatomic molecules
J MOL SPECTROSC , 245 (2) 126 – 140, (2007)

23. CH4

25. CH4

26. CH4

27. CH4

28. Potential energy curve Solve for the motion of the nuclei
Line list: MgH
Ab initio: solve for motion of electrons
Potential energy curve
Dipole moment curve
MOLPRO
Shayesteh et al 2007
MOLPRO
REFINED
Line list: 6690 lines, Nmax=60
Solve for the motion of the nuclei
LEVEL 8.0
R. Le Roy,
Waterloo, Canada
B Yadin et al, MNRAS 425, 34 (2012)

29. Solve for the motion of the nuclei
Line list: CaO
Dipole moment
Potential energy
Khalil et al
(2011)
REFINED
Line list: 22 M lines
Solve for the motion of the nuclei
New program duo
SN Yurchenko et al. Comp Phys Comms ,v.202,p.262 (2016)
SN Yurchenko et al, MNRAS 456, 4524 (2016)

30. Solve for the motion of the nuclei
PH3
Dipole moment
Potential energy
Ab initio PES
[CCSD(T)/aug-cc-pV(Q+d)Z]
Refined using lab spectra
Ab initio:
CCSD(T)/aug-cc-pVTZ
R. I. Ovsyannikov et al.
J. Chem. Phys 129, (2008).
First principles
Predictions of tunnelling being
investigated
Tunneling
motion
neglected
S.N. Yurchenko et al.
J. Mol. Spectrosc 239, 71 (2006).
Solve for the motion of the nuclei
TROVE: Yurchenko, Thiel, Jensen
TROVE
Line list:
TROVE
HITRAN
JPL
JPL
HITRAN
16.8 billion transitions for T up to 1500 K
C Sousa-Silva, MNRAS, 446, 2337 (2015).

31. 10to10 CH4 9D surface Three 9D surfaces 130 000 geometries
Ab initio: solve for motion of electrons
Potential energy
Dipole moment
9D surface
geometries
Three 9D surfaces geometries
Ab initio
10 electrons
Ground
electronic state
MOLPRO
CCSD(T)-f12/QZ
MOLPRO
CCSD(T)-f12/QZ
10to10
Line list:
Solve for the motion of the nuclei
TROVE
Yurchenko, Thiel, Jensen
SN Yurchenko & J Tennyson, MNRAS 440, 1649 (2014)
9.8 Billion transitions

32. Acknowledgment: Andrey Kaliazin Dirac/COSMOS
CH4 diagonalization: Size of the problem
SGI: Jan Wilson,
Simon Appleby
Cheng Liao
LAPACK (DSYEV)
DARWIN
SCALAPACK (PDSYEV)
COSMOS II/DARWIN
Acknowledgment: Andrey Kaliazin Dirac/COSMOS

33. Absorption spectra of CH4: from experimental line list
~ lines
~ 1010 lines
E-17
E-18

35. VSTAR spectra of the T4.5 brown dwarf: a “methane dwarf”
VSTAR STDS CH4 (empirical)
VSTAR ExoMol CH4 (10to10)
SN Yurchenko, J Tennyson, J Bailey, MDJ Hollis, G Tinetti, PNAS, 111, 9379 (2014)
2MASS
T 4.5 Observed
Cushing ,Rayner, Vacca (2005)

36. T =298 K spectrum of nitric acid (HNO3)
A.I. Pavlyuchko, S.N. Yurchenko & J. Tennyson, J. Chem. Phys., 42, (2015)

37. H2OF+H2O H2F+ NH3 H3O+ CH4 H2O H2F+ NH3 H3O+ CH4
Молекулы с числом электронов :
H2OF+H2O
H2F+
NH3
H3O+
CH4
H2O
H2F+
NH3
H3O+
CH4
Вариационные программы:
TROVE (3,4 атома)
DVR3D (3 атом)

38. Figure 1. Schematic energy level diagram employed in experiment.
Our prediction
cm-1
Global ab initio PES so far
~10 cm-1

39. Up to dissociation experiments H2O – up to dissociation NH3 – 18 000 cm-1 HCN – 30 000 cm-1

40. H2O pokazatel
0.01
0.06
-0.02
-0.05
0.04
-0.04
0.00
-0.07
0.02
-0.08
0.05
-0.06
-0.23
-0.01
0.15
0.03
0.83
0.42
0.43
-0.03
0.16
-0.16
-1.72
12565
-8.18
0.67
-0.56
-2.05
0.19
-2.31
0.41
0.56
-5.56
0.22
-2.84
0.54
1.11
0.52
1.22
-0.59
0.25
-4.14
-0.72
1.10
1.99
0.24
3.88
0.11
1.26
-0.92
2.09
-8.59

41. BT2 (water) – 0.5 Billion lines
H216O POKAZATEL
BT2 (water) – 0.5 Billion lines
POKAZATEL – 10 billion lines, first complete
Linelist of polyatomic molecule, every transition
Between every bound state is included
POKAZATEL – PolyanskyOleg,Kyuberis Aleksandra, Zobov nikolAi, TEnnyson, Lodi,(and Yurchenko)

43. NH3 high v
v1 v2 v3 v4L3L4
Obs (cm-1)
Calc (cm-1)
Obs-Calc (cm-1)
6520
0.79
6606
-0.14
-2.56
-2.89
0.64
-0.89
-8.16
-6.92
-15.18
-9.95

44. Calculation of line intensities of highly accurate intensity measurements
0.4% too strong and 1% scatter – pure ab initio

45. 6200-6258 cm-1, 30013 -00001 band, Polyansky OL et al,PRL, v

46. CO sub% intensities 12C17O Intensity ratio experiment/ this work 4-0
4-1
1-0
2-0
6-0
3-0
5-1
5-1
4-0
4-0
m,equals J for P branch, J+1 for R branch

47. Hot line lists Published in MNRAS BeH, MgH, CaH SiO HCN/HNC CH4
NaCl, KCl PN
PH3
H2CO
AlO
NaH
HNO3 CS
CaO
SO2
H2O2
H2S
SO3 VO
H3+
(Virtually) Complete
SH, AlH
H216O (global)
H217O (global)
H218O (global)
HDO (global)
NO, NS
CrH
Planned
MgO
NiH
FeH
Larger
hydrocarbons
In progress
TiO C3
PH, PO, PS
TiH
MnH
NaO
C2H4
SiH
HCCH
CH3Cl
HCN/HNC(global)
SiH4
NH3 (global)
CH4 (global) - project

48. @ExoMol CO2 ScH, TiH H2O NH3 HCN H2O2 CO2 CrH NaCl, KCl C2H4 SO3 SO2
HNO3
NH3 C3
NH3
CH4
VO, TiO
HCCH
PH3
H2CO
HOOH
@ExoMol