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Peer-reviewedCC BY 4.0Monthly Notices of the Royal Astronomical Society

First rotational (de-)excitation of HOCS+( X 1 A ′) by collision with He(1S): rate coefficients and potential energy surface

  • I Ben Salem1
  • A Chefai1
  • O Yazidi1
  • A Al-Ahmadi2
  • K Hammami1
  • H Elabidi3
  1. 1Faculty of Sciences, University of Tunis El Manar LSAMA, Department of Physics, , 1060 Tunis ,
  2. 2College of Science Department of Physics, , Umm Al-Qura University, Makkah Almukarramah, 24382 ,
  3. 3Faculty of Sciences of Bizerte, University of Carthage LR01ES15, Department of Physics, , Zarzouna, 7021 ,
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Abstract

In this work, we constructed the first potential energy surface (PES) for the HOCS+–He complex using the explicitly correlated ab initio CCSD(T)-F12/aug-cc-pVTZ method. An examination of this PES revealed the existence of three potential wells, the deepest of which is 297.25 cm−1, located in the HOCS+ plane, on the hydrogen atom side. We used this PES in dynamical calculations to determine the rate coefficients at which the rotational energy of HOCS+ is exchanged by collisions with He. Rotational transitions involving the lowest 31 energy levels of HOCS+ (up to Erot < 40.2 cm−1) were studied. The quantum close-coupling method (CC) is applied for calculating cross sections at total energies below 50 cm−1. The coupled-states approach (CS) is employed for calculations covering energies up to 500 cm−1. By averaging these cross sections over a Maxwell-Boltzmann distribution, we calculated the rate coefficients for temperatures ranging from 2 to 100 K. In the studied temperature range, a slight dominance of rotational transitions with ΔJ = ΔKc = −1 and ΔKa = 0 was observed. The rate coefficients calculated for HOCS+ ion are compared with those of its valence-isoelectronic molecule HOCO+, specifically for collisions involving He. A similarity was observed, especially for low ΔJ. We expect that the new rate coefficients will help to analyze present and future observations of this key molecule for interstellar chemistry.

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Cite

BibTeXRIS
BibTeX
@article{salem2026first,
  title = {{First rotational (de-)excitation of HOCS+( X 1 A ′) by collision with He(1S): rate coefficients and potential energy surface}},
  author = {I Ben Salem and A Chefai and O Yazidi and A Al-Ahmadi and K Hammami and H Elabidi},
  journal = {Monthly Notices of the Royal Astronomical Society},
  year = {2026},
  month = oct,
  doi = {10.1093/mnras/stag2075},
  url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2075/9005625},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - First rotational (de-)excitation of HOCS+( X 1 A ′) by collision with He(1S): rate coefficients and potential energy surface
AU  - I Ben Salem
AU  - A Chefai
AU  - O Yazidi
AU  - A Al-Ahmadi
AU  - K Hammami
AU  - H Elabidi
PY  - 2026
DA  - 2026/10/30
JO  - Monthly Notices of the Royal Astronomical Society
DO  - 10.1093/mnras/stag2075
UR  - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2075/9005625
AB  - In this work, we constructed the first potential energy surface (PES) for the HOCS+–He complex using the explicitly correlated ab initio CCSD(T)-F12/aug-cc-pVTZ method. An examination of this PES revealed the existence of three potential wells, the deepest of which is 297.25 cm−1, located in the HOCS+ plane, on the hydrogen atom side. We used this PES in dynamical calculations to determine the rate coefficients at which the rotational energy of HOCS+ is exchanged by collisions with He. Rotational transitions involving the lowest 31 energy levels of HOCS+ (up to Erot < 40.2 cm−1) were studied. The quantum close-coupling method (CC) is applied for calculating cross sections at total energies below 50 cm−1. The coupled-states approach (CS) is employed for calculations covering energies up to 500 cm−1. By averaging these cross sections over a Maxwell-Boltzmann distribution, we calculated the rate coefficients for temperatures ranging from 2 to 100 K. In the studied temperature range, a slight dominance of rotational transitions with ΔJ = ΔKc = −1 and ΔKa = 0 was observed. The rate coefficients calculated for HOCS+ ion are compared with those of its valence-isoelectronic molecule HOCO+, specifically for collisions involving He. A similarity was observed, especially for low ΔJ. We expect that the new rate coefficients will help to analyze present and future observations of this key molecule for interstellar chemistry.
SN  - 0035-8711
SN  - 1365-2966
ER  -