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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.04214 |
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Table of Contents:
- We present a unified variational treatment of the magnetic dipole matrix elements, Einstein coefficients and line strength for general open-shell diatomic molecules in the general purpose diatomic code Duo. Building on previous work in which similar expressions for the electric quadrupole transitions were developed, we also present a complete ab initio spectroscopic model for the infrared, electric dipole-forbidden, spectrum of the $^{16}$O$_2$ molecule. The model covers seven states, namely the X $^3Σ^-_g$, a $^1Δ_g$, b $^1Σ^+_g$, I $^1Π_g$, II $^1Π_g$, I $^3Π_g$ and II $^3Π_g$ states, for which 7 potential energy, 6 electronic angular momentum, 7 spin-orbit, and 14 quadrupole moment curves are calculated using ic-MRCI theory and an aug-cc-pV5Z basis set. These curves are diabatised to remove avoided crossings between the excited $Π$ states, and the resultant properties are used to produce a line list for higher-order transitions of astrophysical interest.