A detailed study of the three interacting low-lying electronic states ${}^2\Delta$, ${}^2{\Sigma }^{+}$ and ${}^2\Pi$ of NiH –the so called “supermultiplet” – is presented. A coupled-channels model reproduces the experimental term values of ${}^{58}$NiH, ${}^{60}$NiH and ${}^{62}$NiH with accuracy very close to the estimated uncertainty of 0.01 ${\mathrm{cm}}^{-1}$. The model is based on a set of Hund’s case (a) potential curves and $R$-dependent coupling functions. In addition to the expected spin-orbit and various rotational couplings between the zero-order states, second-order effects are found to be important. The spin-orbit interaction is large compared to the separations between these electronic states, so that most of the observed rovibrational levels are strong mixtures of the $\Omega$ components of the multiplet. The fitting procedure proved difficult because there were no perturbation-free data to determine the starting values for the model functions. For the potential curves we were guided by previous effective Hamiltonian models; ab initio predictions supplied starting values for the spin-orbit and the rotational coupling functions. We believe that this model may be reliably extrapolated to higher rotational levels, with potential applications in the simulation of high temperature spectra, for example in the context of stellar atmospheres.

三种相互作用的低电子态的详细研究 ${}^2\Delta$, ${}^2{\Sigma }^{+}$ 和 ${}^2\Pi$NiH——所谓的“超多重态”——被呈现出来。耦合通道模型再现了实验项值${}^{58}$NIH， ${}^{60}$镍氢和 ${}^{62}$NiH 的精度非常接近估计的不确定性 0.01 ${\mathrm{厘米}}^{-1}$. 该模型基于一组 Hund 的情况 (a) 电位曲线和$\mathrm{电阻}$依赖耦合函数。除了预期的自旋轨道和零级状态之间的各种旋转耦合外，发现二阶效应也很重要。与这些电子态之间的分离相比，自旋轨道相互作用很大，因此大多数观察到的旋转振动能级是$\Omega$多重态的组成部分。拟合过程被证明是困难的，因为没有无扰动数据来确定模型函数的起始值。对于潜在曲线，我们由以前的有效哈密顿模型指导；从头算预测提供了自旋轨道和旋转耦合函数的起始值。我们相信这个模型可以可靠地外推到更高的旋转水平，在高温光谱的模拟中具有潜在的应用，例如在恒星大气的背景下。