Abstract

In this paper, highly correlated <i>ab initio</i> calculations are performed for accurately determining the electronic structures and spectroscopic features of the Λ-S and Ω low-lying electronic states of SbS . The potential energy curves for 27 Λ-S states of the first three dissociation asymptotes are constructed. Spectroscopic constants and vibrational states for all bound states are well determined. The calculated atomic states for both atoms are consistent with experimental data quite well. Several low-lying Ω electronic states are also investigated, and their respective spectroscopic constants and vibrational states are obtained and compared with those of corresponding Λ-S states, which indicates that the spin-orbit coupling effect gives rise to a minor influence on the electronic states of SbS. To verify our computational accuracy, the additional calculations for the low-lying electronic states of PS, AsS and BiS are also carried out. Our derived results are in reasonable agreement with available experimental data. In addition, vibrational spectra from the excited Ω states to the ground state of SbS are simulated, including bands of X(3/2)→X(1/2), 2(1/2)→X(1/2), 4(1/2)→X(1/2), 5(1/2)→X(1/2) and 6(1/2)→X(1/2). The X(3/2)→X(1/2) band is found in the mid-infrared region, while the others are located in the visible region. The predictive results provided in this paper are expected to serve as a guideline for further researches, such as assisting laboratorial detections and analyzing observed spectrum of SbS.

Highlights

  • highly correlated ab initio calculations are performed for accurately determining the electronic structures

  • well determined. The calculated atomic states for both atoms are consistent with experimental data

  • which indicates that the spin-orbit coupling effect gives rise to a minor influence

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Summary

L-S 态的势能曲线与光谱常数

SbS 前三个离解极限相对能量的计算值及对 应的电子态如表 1 所列, 本文计算值与实验值相 比, 符合得很好. 例如 S 原子第一激发态 1Dg 相对 基态 3Pg 的能量为 9346 cm–1, 与实验值 [68] 相差约 1.2%, 而 Sb 原子第一激发态 2Du 与基态 4Su 能量 间隔为 10022 cm–1, 高于实验值 [68] 约 1.7%. 所有 L-S 电子态势能曲线如图 1 所示, 其中14Σ+ , 16Σ+ , 16Π , 22∆ , 34Σ+ , 34∆ , 14Φ , 34Π , 44Π 和54Π 为排 斥态, 其余电子态均为束缚态. Dissociation relationships of the L-S states of SbS. 基态 X2Π 与第一激发态 14Π 在 Re 附近的能量 差超过了 12800 cm–1, 并且没有其他电子态势能曲 线与基态曲线交叉, 表明与其对应的 W 态不会受 到其他 W = 1/2 或 W = 3/2 电子态的影响, 其光 谱常数也不会有大的变化. 在 R = 2.4—3.4 Å, E = 25000—40000 cm–1 范围内, 激发态势能曲线产生 了复杂的曲线 (避免) 交叉, 预示了在此范围内对 其 W 态的分析将具有很大的挑战性. 需要说明的 是, 本文所得电子激发态的谐振频率总体上与文 献 [7] 的数据 (介于 296—442 cm–1 之间) 是相符 的, 但是由于文献 [7] 没有标识电子态, 因此无法 与其数据进行比较. Spectroscopic constants of the L-S states of SbS. 电子组态(组态系数) 15sab7πxabyab8πxa (72.77) 15sab7πxabya8πxaya (84.83) 15sab7πxabyb8πxaya (52.26) 15sab7πxabya8πxayb (31.90) 15sa7πxabyab8πxaya (83.08) 15sab7πxayab8πyab (59.44) 15sab16sa7πxabyab (52.15) 15sa7πxabyab8πxbya (61.23) 15sa7πxabyab8πxayb (60.01) 15sab7πxaya8πxabyb(50.92) 15sa7πxabyab8πyab (38.05) 15sa7πxabyab8πxab (38.05) 15sab16sa7πxabya8πya (35.39) 15sab16sa7πxayab8πxa (35.39) 15sa16sa7πxabyb8πxaya (27.31) 15sa7πxabyab8πyab (16.85) 15sa7πxabyab8πxab (16.85) 15sa7πxayab8πxayab (14.08) 15sa7πxabya8πxabya (14.08) 15sab16sa7πxayab8πya (35.84) 15sab16sa7πxabya 8πxa (35.84) 15sa16sab7πxayab8πxa (17.70) 15sa16sab7πxabya8πya (17.70). 表 3 汇总了氮族元素硫化物自由基的光谱常 数. 通过比较, 发现该系列硫化物基态 X2Π 的光谱 常数体现了同族元素代换后的渐变规律性. 随着氮 族元素核电荷数的增加, Re 逐渐变大, 这源于氮族 元素 np 价电子的弥散性渐强, 而氮族元素与 S 原 子之间的化学键减弱则导致谐振频率 we 逐渐减小

W 态的势能曲线与光谱常数
L-S 态与 W 态的振动能级和转动常数
W 态的振动跃迁
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