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Title: Inelastic rate coefficients for collisions of C4H- with H2

Journal Article · · Monthly Notices of the Royal Astronomical Society
 [1]; ORCiD logo [2];  [2];  [3];  [4];  [1]
  1. Observatoire de Paris, Université PSL, Meudon, France
  2. Missouri University of Science and Technology, Rolla, MO (United States)
  3. University in Le Havre, France
  4. Observatoire de Paris, Université PSL, Meudon, France; University in Le Havre, France; ; University of Rennes (France)
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Carbon-chain anions were recently detected in the interstellar medium. These very reactive species are used as tracers of the physical and chemical conditions in a variety of astrophysical environments. However, the local thermodynamic equilibrium conditions are generally not fulfilled in these environments. Therefore, collisional as well as radiative rates are needed to accurately model the observed emission lines. We determine in this work the state-to-state rate coefficients of C4H- in collision with both ortho- and para-H2. A new ab initio 4D potential energy surface was computed using explicitly correlated coupled-cluster procedures. This surface was then employed to determine rotational excitation and de-excitation cross-sections and rate coefficients for the first 21 rotational levels (up to rotational level j1 = 20) using the close-coupling method, while the coupled-state approximation was used to extend the calculations up to j1 = 30. State-to-state rate coefficients were obtained for the temperature range 2–100K. The differences between the ortho- and para-H2 rate coefficients are found to be small.

Research Organization:
Univ. of Missouri, Columbia, MO (United States)
Sponsoring Organization:
USDOE Office of Science (SC); Centre National d’Etudes Spatiales (CNES); Programme National de Physique Stellaire (PNPS); National Science Foundation (NSF)
Grant/Contract Number:
SC0019740; 2010040883; OAC-1919789
OSTI ID:
1979514
Journal Information:
Monthly Notices of the Royal Astronomical Society, Vol. 508, Issue 1; ISSN 0035-8711
Publisher:
Oxford University PressCopyright Statement
Country of Publication:
United States
Language:
English

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