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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
Subject(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.
Issue Date:2021-06-25
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Date Available in IDEALS:2021-09-24

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