Collisional excitation of NH by H2: Potential energy surface and scattering calculations
| Autor: | Ragav Ramachandran, Yulia N. Kalugina, Paul J. Dagdigian, Paul Pirlot, François Lique, Guillaume Raffy |
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| Přispěvatelé: | Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Russian Academy of Sciences [Moscow] (RAS), Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Johns Hopkins University (JHU), Horizon 2020 Framework Programme, H2020: 811363, European Research Council, ERC, Institut Universitaire de France, IUF, Russian Science Foundation, RSF: 17-12-01395, Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
General Physics and Astronomy
010402 general chemistry 01 natural sciences Molecular physics Atomic physics symbols.namesake Collisional excitation Van der Waals forces Potential energy Ab initio quantum chemistry methods Fine structures 0103 physical sciences поверхности потенциальной энергии столкновения молекул Coupled clusters methods Physical and Theoretical Chemistry Quantum dynamics Basis set Van der Waals complex Physics [PHYS]Physics [physics] 010304 chemical physics Potential-energy surfaces Bond-dissociation energy Correlation consistent polarized valence 0104 chemical sciences Scattering calculations Coupled cluster потенциальная энергия Potential energy surfaces Potential energy surface symbols Collisional Ab initio calculations Numerical methods Atomic and molecular collisions van der Waals force Perturbative triple excitations Calculations Quantum chemistry Excitation |
| Zdroj: | Journal of chemical physics. 2021. Vol. 155, № 13. P. 134303-1-134303-9 Journal of Chemical Physics Journal of Chemical Physics, American Institute of Physics, 2021, 155 (13), pp.134303. ⟨10.1063/5.0066161⟩ Journal of Chemical Physics, 2021, 155 (13), pp.134303. ⟨10.1063/5.0066161⟩ |
| ISSN: | 0021-9606 1089-7690 |
| DOI: | 10.1063/5.0066161⟩ |
| Popis: | Collisional data for the excitation of NH by H2 are key to accurately derive the NH abundance in astrophysical media. We present a new four-dimensional potential energy surface (PES) for the NH–H2 van der Waals complex. The ab initio calculations of the PES were carried out using the explicitly correlated partially spin-restricted coupled cluster method with single, double, and perturbative triple excitations [RCCSD(T)-F12a] with the augmented correlation-consistent polarized valence triple zeta basis set. The PES was represented by an angular expansion in terms of coupled spherical harmonics. The global minimum corresponds to the linear structure with a well depth D e = 149.10 cm−1. The calculated dissociation energy D0 is found to be 30.55 and 22.11 cm−1 for ortho-H2 and para-H2 complexes, respectively. These results are in agreement with the experimental values. Then, we perform quantum close-coupling calculations of the fine structure resolved excitation cross sections of NH induced by collisions with ortho-H2 and para-H2 for collisional energies up to 500 cm−1. We find strong differences between collisions induced by ortho-H2 and para-H2. Propensity rules are discussed. The cross sections are larger for fine structure conserving transitions than for fine structure changing ones, as predicted by theory. These new results should help in interpreting NH interstellar spectra and better constrain the abundance of NH in interstellar molecular clouds. |
| Databáze: | OpenAIRE |
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