Improved Hot Line Lists for Minor CN Isotopologues in the X ² Σ ⁺ , A ² Π, and B ² Σ ⁺ Systems Using Diagonal Born–Oppenheimer Corrections
- 1Lomonosov Moscow State University
- 2University College London
Abstract
We present improved hot line lists for optical transitions between the mutually perturbed B ² Σ ⁺ , A ² Π, and X ² Σ ⁺ states of the minor CN isotopologues ¹³ C ¹⁴ N, ¹² C ¹⁵ N, and ¹³ C ¹⁵ N. Accurate line positions and intensities for these isotopologues are required for high-resolution analyses of stellar CN red-system spectra and cometary CN violet-band fluorescence, where minor-isotopologue features are used to infer carbon and nitrogen isotopic ratios. The rovibronic energies and transition probabilities were recalculated by explicitly incorporating mass-dependent diagonal Born–Oppenheimer corrections (DBOCs) into the semiempirical potential energy curves recently derived for the B , A , and X states for the main ¹² C ¹⁴ N isotopologue. For the X and A states, the radial DBOC functions were initially estimated during electronic structure calculations accomplished at the CCSDT/cc-pVDZ level of theory. The inclusion of the ab initio DBOCs significantly improves the accuracy of the A − X and B − X positions by reducing the root-mean-square error (RMSE) in the description of the experimental A − X and B − X lines of the ¹³ C ¹⁴ N [ ¹² C ¹⁵ N] isotopologues from 0.24 [0.15] and 0.16 [0.05] cm ⁻¹ to 0.04 [0.01] and 0.08 [0.05] cm ⁻¹ , respectively. A subsequent simultaneous adjustment of the DBOC functions for all three B , A , and X states to the experimental ¹³ C ¹⁴ N lines further decreased the RMSE of the predicted wavenumbers for the minor ¹³ C ¹⁴ N and ¹² C ¹⁵ N isotopologues to the spectroscopic level of accuracy. The new KTPSYT-iso line lists are made available via www.exomol.com .
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BibTeX
@article{terashkevich2026improved,
title = {{Improved Hot Line Lists for Minor CN Isotopologues in the X ² Σ ⁺ , A ² Π, and B ² Σ ⁺ Systems Using Diagonal Born–Oppenheimer Corrections}},
author = {V. A. Terashkevich and S. V. Kozlov and E. A. Pazyuk and A. V. Stolyarov and S. N. Yurchenko and J. Tennyson},
journal = {The Astrophysical Journal Supplement Series},
year = {2026},
month = oct,
doi = {10.3847/1538-4365/aea220},
url = {https://iopscience.iop.org/article/10.3847/1538-4365/aea220},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Improved Hot Line Lists for Minor CN Isotopologues in the X ² Σ ⁺ , A ² Π, and B ² Σ ⁺ Systems Using Diagonal Born–Oppenheimer Corrections
AU - V. A. Terashkevich
AU - S. V. Kozlov
AU - E. A. Pazyuk
AU - A. V. Stolyarov
AU - S. N. Yurchenko
AU - J. Tennyson
PY - 2026
DA - 2026/10/27
JO - The Astrophysical Journal Supplement Series
DO - 10.3847/1538-4365/aea220
UR - https://iopscience.iop.org/article/10.3847/1538-4365/aea220
AB - We present improved hot line lists for optical transitions between the mutually perturbed B ² Σ ⁺ , A ² Π, and X ² Σ ⁺ states of the minor CN isotopologues ¹³ C ¹⁴ N, ¹² C ¹⁵ N, and ¹³ C ¹⁵ N. Accurate line positions and intensities for these isotopologues are required for high-resolution analyses of stellar CN red-system spectra and cometary CN violet-band fluorescence, where minor-isotopologue features are used to infer carbon and nitrogen isotopic ratios. The rovibronic energies and transition probabilities were recalculated by explicitly incorporating mass-dependent diagonal Born–Oppenheimer corrections (DBOCs) into the semiempirical potential energy curves recently derived for the B , A , and X states for the main ¹² C ¹⁴ N isotopologue. For the X and A states, the radial DBOC functions were initially estimated during electronic structure calculations accomplished at the CCSDT/cc-pVDZ level of theory. The inclusion of the ab initio DBOCs significantly improves the accuracy of the A − X and B − X positions by reducing the root-mean-square error (RMSE) in the description of the experimental A − X and B − X lines of the ¹³ C ¹⁴ N [ ¹² C ¹⁵ N] isotopologues from 0.24 [0.15] and 0.16 [0.05] cm ⁻¹ to 0.04 [0.01] and 0.08 [0.05] cm ⁻¹ , respectively. A subsequent simultaneous adjustment of the DBOC functions for all three B , A , and X states to the experimental ¹³ C ¹⁴ N lines further decreased the RMSE of the predicted wavenumbers for the minor ¹³ C ¹⁴ N and ¹² C ¹⁵ N isotopologues to the spectroscopic level of accuracy. The new KTPSYT-iso line lists are made available via www.exomol.com .
SN - 0067-0049
SN - 1538-4365
ER -