Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere

Light–matter interactions lie at the heart of our exploration of exoplanetary atmospheres. Interpreting data obtained by remote sensing is enabled by meticulous, time- and resource-consuming work aiming at deepening our understanding of such interactions (i.e., opacity models). Recently, P. Niraula...

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Main Authors: Laurent Wiesenfeld, Prajwal Niraula, Julien de Wit, Nejmeddine Jaïdane, Iouli E. Gordon, Robert J. Hargreaves
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adb02e
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author Laurent Wiesenfeld
Prajwal Niraula
Julien de Wit
Nejmeddine Jaïdane
Iouli E. Gordon
Robert J. Hargreaves
author_facet Laurent Wiesenfeld
Prajwal Niraula
Julien de Wit
Nejmeddine Jaïdane
Iouli E. Gordon
Robert J. Hargreaves
author_sort Laurent Wiesenfeld
collection DOAJ
description Light–matter interactions lie at the heart of our exploration of exoplanetary atmospheres. Interpreting data obtained by remote sensing is enabled by meticulous, time- and resource-consuming work aiming at deepening our understanding of such interactions (i.e., opacity models). Recently, P. Niraula et al. pointed out that due primarily to limitations on our modeling of broadening and far-wing behaviors, opacity models needed a timely update for exoplanet exploration in the JWST era, and thus argued for a scalable approach. In this proof-of-concept study, we introduce an end-to-end solution from ab initio calculations to pressure broadening, and use a perturbation framework to address the need for precision to a level of ∼10%. We focus on the CO _2 –H _2 system as CO _2 is a key absorption feature for exoplanet research (primarily in many gas giants) at ∼4.3 μ m as pressure-broadening parameters required for interpreting such observations remain sparse. We compute elastic and inelastic cross sections for the collisions of ortho-H _2 with CO _2 , in the ground vibrational state, and at the coupled-channel fully converged level. For scattering energies above ∼20 cm ^−1 , moderate precision intermolecular potentials are indistinguishable from high-precision ones in cross sections. Our calculations agree with the currently available measurements within 7%, i.e., well beyond the precision requirements.
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spelling doaj-art-ff4f5c19d2ac4da08c7273f88f5e4bd42025-08-20T03:15:16ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01981214810.3847/1538-4357/adb02eAb Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen AtmosphereLaurent Wiesenfeld0https://orcid.org/0000-0003-2355-4543Prajwal Niraula1https://orcid.org/0000-0002-8052-3893Julien de Wit2https://orcid.org/0000-0003-2415-2191Nejmeddine Jaïdane3Iouli E. Gordon4https://orcid.org/0000-0003-4763-2841Robert J. Hargreaves5https://orcid.org/0000-0002-7691-6926Université Paris-Saclay , CNRS, Laboratoire Aimé-Cotton, 91405 Orsay, France ; laurent.wiesenfeld@universite-paris-saclay.fr; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; pniraula@mit.eduDepartment of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; pniraula@mit.eduDepartment of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USA ; pniraula@mit.eduUniversité Paris-Saclay , CNRS, Laboratoire Aimé-Cotton, 91405 Orsay, France ; laurent.wiesenfeld@universite-paris-saclay.fr; Université Tunis El Manar , Faculty of Sciences, Tunis, TunisiaHarvard-Smithsonian Center for Astrophysics , Atomic and Molecular Physics Division, Cambridge, MA, USAHarvard-Smithsonian Center for Astrophysics , Atomic and Molecular Physics Division, Cambridge, MA, USALight–matter interactions lie at the heart of our exploration of exoplanetary atmospheres. Interpreting data obtained by remote sensing is enabled by meticulous, time- and resource-consuming work aiming at deepening our understanding of such interactions (i.e., opacity models). Recently, P. Niraula et al. pointed out that due primarily to limitations on our modeling of broadening and far-wing behaviors, opacity models needed a timely update for exoplanet exploration in the JWST era, and thus argued for a scalable approach. In this proof-of-concept study, we introduce an end-to-end solution from ab initio calculations to pressure broadening, and use a perturbation framework to address the need for precision to a level of ∼10%. We focus on the CO _2 –H _2 system as CO _2 is a key absorption feature for exoplanet research (primarily in many gas giants) at ∼4.3 μ m as pressure-broadening parameters required for interpreting such observations remain sparse. We compute elastic and inelastic cross sections for the collisions of ortho-H _2 with CO _2 , in the ground vibrational state, and at the coupled-channel fully converged level. For scattering energies above ∼20 cm ^−1 , moderate precision intermolecular potentials are indistinguishable from high-precision ones in cross sections. Our calculations agree with the currently available measurements within 7%, i.e., well beyond the precision requirements.https://doi.org/10.3847/1538-4357/adb02eTransmission spectroscopyInfrared spectroscopyJames Webb Space TelescopeLaboratory astrophysicsSpectral line listsAstronomy data analysis
spellingShingle Laurent Wiesenfeld
Prajwal Niraula
Julien de Wit
Nejmeddine Jaïdane
Iouli E. Gordon
Robert J. Hargreaves
Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
The Astrophysical Journal
Transmission spectroscopy
Infrared spectroscopy
James Webb Space Telescope
Laboratory astrophysics
Spectral line lists
Astronomy data analysis
title Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
title_full Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
title_fullStr Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
title_full_unstemmed Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
title_short Ab Initio Quantum Dynamics as a Scalable Solution to the Exoplanet Opacity Challenge: A Case Study of CO2 in a Hydrogen Atmosphere
title_sort ab initio quantum dynamics as a scalable solution to the exoplanet opacity challenge a case study of co2 in a hydrogen atmosphere
topic Transmission spectroscopy
Infrared spectroscopy
James Webb Space Telescope
Laboratory astrophysics
Spectral line lists
Astronomy data analysis
url https://doi.org/10.3847/1538-4357/adb02e
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