J/A+A/685/A113 Rovibrational (de-)excitation of H2 by He (Jozwiak+, 2024)
Revisiting the rovibrational (de-)excitation of molecular hydrogen by helium.
Jozwiak H., Thibault F., Viel A., Wcislo P., Lique F.
<Astron. Astrophys. 685, A113 (2024)>
=2024A&A...685A.113J 2024A&A...685A.113J (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: molecular data - radiative transfer - scattering - ISM: molecules
Abstract:
The collisional (de-)excitation of H2 by He plays an important role in
the thermal balance and chemistry of various astrophysical
environments, making accurate rate coefficients essential for
interpreting observations of the interstellar medium.
Our goal is to utilize a state-of-the-art potential energy surface
(PES) to provide comprehensive state-to-state rate coefficients for
He-induced transitions among rovibrational levels of H2.
We performed quantum scattering calculations for the H2-He system.
Thus, we were able to provide state-to-state rate coefficients for
1059 transitions between rovibrational levels of H2, with internal
energies up to 15000cm-1, for temperatures ranging from 20 to 8000K.
Our results demonstrate a good agreement with previous calculations
for pure rotational transitions between low-lying rotational levels.
However, we do find significant discrepancies for rovibrational
processes involving highly-excited rotational and vibrational states.
We attribute these differences to two key factors: 1) the broader
range of intramolecular distances covered by ab initio points and 2)
the superior accuracy of the PES, resulting from the utilization of
the state-of-the-art quantum chemistry methods, compared to previous
lower-level calculations.
Radiative transfer calculations performed with the new collisional
data indicate that the population of rotational levels in excited
vibrational states experiences significant modifications, highlighting
the critical need for this updated dataset in models of
high-temperature astrophysical environments.
Description:
The state-to-state rate coefficients for rovibrational (de-)excitation
of H2 by He. Transitions between rovibrational levels of H2 with
internal energies lower than 15000cm-1 are considered. There are 26
such levels in ortho-H2 (see oh2-lev.dat), and 27 such levels in
para-H2 (see ph2-lev.dat), and thus 676 possible transitions for
ortho-H2 and 729 for para-H2. In our study, we achieved
satisfactory convergence of cross-sections (10% or better) for 520
(out of 676) transitions in the ortho-H2 case and for 539 (out of
729) transitions in the para-H2 case. Rate coefficients for these
transitions are provided in oh2-rat.dat and ph2-rat.dat, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
oh2-lev.dat 7 26 List of rovibrational levels of ortho-H2
ph2-lev.dat 7 27 List of rovibrational levels of para-H2
oh2-rat.dat 654 520 Rate coefficients for ortho-H2
ph2-rat.dat 654 539 Rate coefficients for para-H2
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Byte-by-byte Description of file: oh2-lev.dat ph2-lev.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- i Level label
4- 5 I2 --- J Rotational quantum number J
7 I1 --- v Vibrational quantum number v
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Byte-by-byte Description of file: oh2-rat.dat ph2-rat.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- n Transition label
5- 6 I2 --- i Initial level label (see *h2-lev.dat)
8- 9 I2 --- f Final level label (see *h2-lev.dat)
13- 24 E12.5 cm3/s RC20 Rate coefficient for T=20K
28- 39 E12.5 cm3/s RC30 Rate coefficient for T=30K
43- 54 E12.5 cm3/s RC40 Rate coefficient for T=40K
59- 69 E11.5 cm3/s RC50 Rate coefficient for T=50K
73- 84 E12.5 cm3/s RC60 Rate coefficient for T=60K
89- 99 E11.5 cm3/s RC70 Rate coefficient for T=70K
103-114 E12.5 cm3/s RC80 Rate coefficient for T=80K
118-129 E12.5 cm3/s RC90 Rate coefficient for T=90K
133-144 E12.5 cm3/s RC100 Rate coefficient for T=100K
148-159 E12.5 cm3/s RC120 Rate coefficient for T=120K
164-174 E11.5 cm3/s RC140 Rate coefficient for T=140K
179-189 E11.5 cm3/s RC160 Rate coefficient for T=160K
194-204 E11.5 cm3/s RC180 Rate coefficient for T=180K
209-219 E11.5 cm3/s RC200 Rate coefficient for T=200K
224-234 E11.5 cm3/s RC250 Rate coefficient for T=250K
239-249 E11.5 cm3/s RC300 Rate coefficient for T=300K
254-264 E11.5 cm3/s RC350 Rate coefficient for T=350K
269-279 E11.5 cm3/s RC400 Rate coefficient for T=400K
284-294 E11.5 cm3/s RC450 Rate coefficient for T=450K
299-309 E11.5 cm3/s RC500 Rate coefficient for T=500K
314-324 E11.5 cm3/s RC550 Rate coefficient for T=550K
329-339 E11.5 cm3/s RC600 Rate coefficient for T=600K
344-354 E11.5 cm3/s RC650 Rate coefficient for T=650K
359-369 E11.5 cm3/s RC700 Rate coefficient for T=700K
374-384 E11.5 cm3/s RC750 Rate coefficient for T=750K
389-399 E11.5 cm3/s RC800 Rate coefficient for T=800K
404-414 E11.5 cm3/s RC850 Rate coefficient for T=850K
419-429 E11.5 cm3/s RC900 Rate coefficient for T=900K
434-444 E11.5 cm3/s RC950 Rate coefficient for T=950K
449-459 E11.5 cm3/s RC1000 Rate coefficient for T=1000K
464-474 E11.5 cm3/s RC1100 Rate coefficient for T=1100K
479-489 E11.5 cm3/s RC1200 Rate coefficient for T=1200K
494-504 E11.5 cm3/s RC1300 Rate coefficient for T=1300K
509-519 E11.5 cm3/s RC1400 Rate coefficient for T=1400K
524-534 E11.5 cm3/s RC1500 Rate coefficient for T=1500K
539-549 E11.5 cm3/s RC1750 Rate coefficient for T=1750K
554-564 E11.5 cm3/s RC2000 Rate coefficient for T=2000K
569-579 E11.5 cm3/s RC3000 Rate coefficient for T=3000K
584-594 E11.5 cm3/s RC4000 Rate coefficient for T=4000K
599-609 E11.5 cm3/s RC5000 Rate coefficient for T=5000K
614-624 E11.5 cm3/s RC6000 Rate coefficient for T=6000K
629-639 E11.5 cm3/s RC7000 Rate coefficient for T=7000K
644-654 E11.5 cm3/s RC8000 Rate coefficient for T=8000K
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History:
From Hubert Jozwiak, hubert.jozwiak(at)umk.pl
Acknowledgements:
We acknowledge financial support from the European Research Council
(Consolidator Grant COLLEXISM, Grant Agreement No. 811363), and the
financial support of the University of Rennes via a grant project dedicated
to international collaborations and via the CNRS IRN MCTDH grant.
H.J. is supported by the Foundation for Polish Science (FNP) and by the
National Science Centre in Poland through Project No. 2019/35/B/ST2/01118.
P.W. is supported by the National Science Centre in Poland through
Project No. 2022/46/E/ST2/00282.
(End) Patricia Vannier [CDS] 06-Mar-2024