A Coupled-channels Potential Fit Describing The Low-lying X²∆, ²Π And ²Σ⁺ States Of Nih To Experimental Accuracy

Havalyova, Ilvie

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https://hdl.handle.net/2142/111174 Copy

Description

Title

A Coupled-channels Potential Fit Describing The Low-lying X²∆, ²Π And ²Σ⁺ States Of Nih To Experimental Accuracy

Author(s)

Havalyova, Ilvie

Contributor(s)

• Crozet, Patrick
• Ross, Amanda J.
• Pashov, Asen
• BOZHINOVA, Ivayla

Issue Date

2021-06-25

Keyword(s)

Small molecules

Abstract

A direct potential fit to Hund's case (a) potential curves for the low-lying `supermultiplet' states (${X{}^2\Delta}$, ${{}^2\Pi}$, ${}^2\Sigma^{+}$) of NiH and to R-dependent spin-orbit and rotational coupling functions has reproduced the experimental term values of $^{58}$NiH, $^{60}$NiH, $^{62}$NiH up to 6500 cm$^{-1}$, with a root mean square deviation very close to the estimated uncertainty of 0.01 cm$^{-1}$. Second-order Born-Oppenheimer breakdown corrections to the rotational Hamiltonian had to be included to achieve this result. The spin-orbit interaction A$_{so}$(R) associated with Ni$^{+}$ is large compared to the energy separations between the three electronic states, so that most of the observed rovibrational states are strong mixtures of the $\Omega$-components of the multiplet. This made the fitting procedure particularly difficult, because there were no perturbation-free data to determine the starting values for the model functions. Potential curves were optimized from RKR turning-points generated from earlier work using an effective Hamiltonian approach\footnote{M. Abbasi $et~al$, J. Mol. Spectrosc. \underline{349} 49-59 (2018)}, and the spin-orbit and rotational coupling functions from theoretical predictions\footnote{C. Marian, J. Chem. Phys., \underline{93(2)} 1176-1186 (1990)}. We believe that this model may be reliably extrapolated to higher rotational states, with potential applications in the simulation of high temperature spectra, for example in the context of stellar atmospheres.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111174

DOI

10.15278/isms.2021.FL06

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