摘要:
基于全电子的相关一致极化4-ζ(aug-cc-pwCVQZ-DK)基组,采用高精度的多参考组态相互作用方法计算了SiS自由基与最低的解离极限Si(3Pg)+S(3Pg)对应的18个Λ-S电子态的势能曲线。计算中考虑了标量相对论效应以及Si(2s22p6)和S(2s22p6)内壳层电子产生的关联效应。基于计算的势能曲线,拟合出了束缚态的光谱参数,包括平衡核间距Re,绝热激发能Te,振动常数ωe和ωeχe,平衡转动常数Be；并分析了束缚态在不同键长位置处的电子组态。计算了18个Λ-S态的电偶极矩函数,阐明了电子态的组态变化对电偶极矩的影响。给出了包含b3Π和A1Π态的自旋-轨道矩阵元随核间距变化的曲线,分析了邻近的电子激发态对b3Π和A1Π态的扰动。计算了A1Π-X1Σ+和E1Σ+-X1Σ+跃迁的跃迁偶极矩和Franck-Condon因子,讨论了A1Π和E1Σ+的最低五个振动能级的辐射寿命。
Abstract:
The 18 Λ-S states correlated to the lowest dissociation (Si(3Pg)+S(3Pg)) limit are computed with high-level mul-tireference configuration interaction (MRCI(SD)) approach through utilizing all-electron aug-cc-pwCVQZ-DK basis set. The scalar relativistic effect and the core-valence correlation effect of Si (2s22p6) and S (2s22p6) are taken into account. On the basis of calculated potential energy curves, the spectroscopic constants of the bound states are fitted, including equilibrium distance Re , adiabatic transition energies Te , harmonic vibrational frequenciesωe , anharmonic termsωe xe , and rotational constant Be . The electronic configurations at different bond lengths are given. The electronic dipole moments of 18 Λ-S states are calculated, illuminating the influence of electronic configuration variation on electronic dipole moment. With the help of nonvanishing spin-orbit matrixelements including b3Π and A1Π as a function of the internuclear distance, the nearby state perturbations to b3Π and A1Π are discussed in detail. Finally, the transition dipole moments and Franck-Condon factors of A1Π-X1Σ+ and E1Σ+-X1Σ+ transitions are obtained, and radiative lifetimes of five lowest vibrational levels of the two singlet excited states are evaluated.
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