Comprehensive \textsl{Ab Initio}~Calculations of \ce{CO2-H2} and \ce{CO2-He} Collisional Properties
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arXiv
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| Auteurs principaux: | , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866916987793309696 |
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| author | Niraula, Prajwal Wiesenfeld, Laurent Jaïdane, Nejmeddine de Wit, Julien Hargreaves, Robert J. Kepner, Jeremy Woods, Deborah Loughlin, Cooper Gordon, Iouli E. |
| author_facet | Niraula, Prajwal Wiesenfeld, Laurent Jaïdane, Nejmeddine de Wit, Julien Hargreaves, Robert J. Kepner, Jeremy Woods, Deborah Loughlin, Cooper Gordon, Iouli E. |
| contents | We present comprehensive \textsl{ab initio} calculations of CO$_{\rm 2}$-H$_{\rm 2}$ and CO$_{\rm 2}$-He collisional properties from first principles, employing CCSD(T), potential calculations together with close-coupling dynamical scattering in the \YUMI~framework. We derive (in)elastic cross sections, rate coefficients, and pressure-broadening parameters -- incl., their rotational dependence up to $|m|=50$, and temperature dependence over the range of 100-800 K. We provide Padé fits for the broadening coefficients as a function of rotational quantum number, enabling extrapolation of the results and integration into spectroscopic databases, including HITRAN and HITEMP. The computed potentials for both CO$_{\rm 2}$-H$_{\rm 2}$ and CO$_{\rm 2}$-He have a sub-percent precision, and the dynamics-solving code YUMI ultimately yields the collisional parameters. Among these, the scaled pressure broadening experimental values meet the 10\% precision requirement for exoplanetary sciences with \textit{JWST}. This contrasts with the parameters available before the present calculations, which at higher temperatures (T$>$400 K) deviate as much as 5$\times$ from the desired precision requirement. All derivations and collisional properties are provided with this manuscript, establishing the first of such a comprehensive ab initio foundation for collisional systems with a target molecule having more than two atoms. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_03327 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Comprehensive \textsl{Ab Initio}~Calculations of \ce{CO2-H2} and \ce{CO2-He} Collisional Properties Niraula, Prajwal Wiesenfeld, Laurent Jaïdane, Nejmeddine de Wit, Julien Hargreaves, Robert J. Kepner, Jeremy Woods, Deborah Loughlin, Cooper Gordon, Iouli E. Chemical Physics Earth and Planetary Astrophysics We present comprehensive \textsl{ab initio} calculations of CO$_{\rm 2}$-H$_{\rm 2}$ and CO$_{\rm 2}$-He collisional properties from first principles, employing CCSD(T), potential calculations together with close-coupling dynamical scattering in the \YUMI~framework. We derive (in)elastic cross sections, rate coefficients, and pressure-broadening parameters -- incl., their rotational dependence up to $|m|=50$, and temperature dependence over the range of 100-800 K. We provide Padé fits for the broadening coefficients as a function of rotational quantum number, enabling extrapolation of the results and integration into spectroscopic databases, including HITRAN and HITEMP. The computed potentials for both CO$_{\rm 2}$-H$_{\rm 2}$ and CO$_{\rm 2}$-He have a sub-percent precision, and the dynamics-solving code YUMI ultimately yields the collisional parameters. Among these, the scaled pressure broadening experimental values meet the 10\% precision requirement for exoplanetary sciences with \textit{JWST}. This contrasts with the parameters available before the present calculations, which at higher temperatures (T$>$400 K) deviate as much as 5$\times$ from the desired precision requirement. All derivations and collisional properties are provided with this manuscript, establishing the first of such a comprehensive ab initio foundation for collisional systems with a target molecule having more than two atoms. |
| title | Comprehensive \textsl{Ab Initio}~Calculations of \ce{CO2-H2} and \ce{CO2-He} Collisional Properties |
| topic | Chemical Physics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2510.03327 |