The spin-forbidden transitions of MgO are very important to the photodissociation dynamics and chemical reaction dynamics, which are frequently occurred in the interstellar space. In this work, the internally contracted multireference configuration interaction (icMRCI) method with the Davidson correction is used to compute the adiabatic potential energy curves (PECs) of eight Λ-S electronic states of MgO. Through considering the spin-orbit coupling (SOC) effect, the PECs of six splitting electronic states and the spin-forbidden transition dipole moments (TDMs) between the six lowest lying Ω states are also calculated. Using the calculated PECs and TDMs, the adiabatic transition parameters, including the Franck-Condon factors (FCFs) and radiative lifetimes for spin-forbidden transitions (${\mathrm{a}}^3{\Pi }_{0^{+},1}-{\mathrm{X}}^1{\Sigma }_{0^{+}}^{+}$ and ${\mathrm{A}}^1{\Pi }_1-{\mathrm{a}}^3{\Pi }_{0^{+},1}$), are determined. As for the ${\mathrm{a}}^3{\Pi }_{0^{+},1}-{\mathrm{X}}^1{\Sigma }_{0^{+}}^{+}$transition, the radiative lifetimes are shorter, which means the stronger emission could occur. The FCFs for the ${\mathrm{A}}^1{\Pi }_1-{\mathrm{a}}^3{\Pi }_{0^{+},1}$ transition are highly diagonal and the values are greater than 0.94, but with large vibrational radiative lifetimes. The results obtained in this work are consistent with experimental ones and can be used to further investigate the mechanism of chemical reaction dynamics.

MgO的自旋禁止跃迁对光解离动力学和化学反应动力学非常重要，光解离动力学和化学反应动力学经常发生在星际空间中。在这项工作中，使用具有Davidson校正的内部收缩多参考配置相互作用（icMRCI）方法来计算MgO的八个Λ-S电子态的绝热势能曲线（PEC）。通过考虑自旋轨道耦合（SOC）效应，还计算了六个分裂电子状态的PEC和六个最低Ω状态之间的自旋禁止跃迁偶极矩（TDM）。使用计算出的PEC和TDM，绝热跃迁参数，包括弗兰克-康登因子（FCF）和自旋禁忌跃迁的辐射寿命（${\mathrm{一种}}^3{\Pi }_{0^{+}，\mathrm{1个}}-{\mathrm{X}}^{\mathrm{1个}}{\Sigma }_{0^{+}}^{+}$ 和 ${\mathrm{一种}}^{\mathrm{1个}}{\Pi }_{\mathrm{1个}}-{\mathrm{一种}}^3{\Pi }_{0^{+}，\mathrm{1个}}$），确定。至于${\mathrm{一种}}^3{\Pi }_{0^{+}，\mathrm{1个}}-{\mathrm{X}}^{\mathrm{1个}}{\Sigma }_{0^{+}}^{+}$过渡，辐射寿命较短，这意味着可能发生更强的发射。的FCF${\mathrm{一种}}^{\mathrm{1个}}{\Pi }_{\mathrm{1个}}-{\mathrm{一种}}^3{\Pi }_{0^{+}，\mathrm{1个}}$过渡是高度对角线的，并且该值大于0.94，但是具有较大的振动辐射寿命。这项工作获得的结果与实验结果一致，可用于进一步研究化学反应动力学的机理。