The potential energy curves (PECs) for six low-lying states corresponding to the first dissociation limit (S+P) of the NO, PO, and PS molecules are calculated by the multireference configuration interaction (MRCI) method. The XΠ -aΠ band is the focus of this work. By introducing the spin-orbit coupling (SOC) with Breit-Pauli operator via technique, the PECs and wavefunctions compositions of Ω states are obtained. Based on the Λ-S states composition of the corresponding Ω states and the calculated electric-dipole transition moments between Λ-S state, we present intensity of the spin-forbidden quartet-doublet bands. Spectroscopic constants for all sub-bands of the Π, Π, Π→XΠ and Π, Π, Π, Π→XΠ systems of the NO, PO, and PS are estimated. A set of transition parameters of these sub-bands are given. The present results are supposed to provide a significant supplement for the spin-forbidden Π→XΠ band origins of the astrophysically important NO, PO, and PS molecules.

中文翻译：

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NO、PO 和 PS 分子中自旋禁阻 a4Π-X2Π 系统的跃迁性质

通过多参考构型相互作用（MRCI）方法计算了对应于NO、PO和PS分子第一解离极限（S+P）的六个低位能态的势能曲线（PEC）。 XΠ -aΠ 带是这项工作的重点。通过技术引入Breit-Pauli算子的自旋轨道耦合(SOC)，获得了Ω态的PEC和波函数组成。基于相应 Ω 态的 Λ-S 态组成和计算出的 Λ-S 态之间的电偶极跃迁矩，我们给出了自旋禁阻四重态-双态能带的强度。估计了 NO、PO 和 PS 的 Π、Π、Π→XΠ 和 Π、Π、Π、Π→XΠ 系统的所有子带的光谱常数。给出了这些子带的一组过渡参数。目前的结果有望为天体物理学上重要的NO、PO和PS分子的自旋禁带Π→XΠ带起源提供重要的补充。