Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
J Chem Phys. 2012 Aug 7;137(5):054313. doi: 10.1063/1.4739756.
Global three dimensional potential energy surfaces and transition dipole moment functions are calculated for the lowest singlet and triplet states of carbonyl sulfide at the multireference configuration interaction level of theory. The first ultraviolet absorption band is then studied by means of quantum mechanical wave packet propagation. Excitation of the repulsive 2 (1)A' state gives the main contribution to the cross section. Excitation of the repulsive 1 (1)A" state is about a factor of 20 weaker at the absorption peak (E(ph) ≈ 45,000 cm(-1)) but becomes comparable to the 2 (1)A' state absorption with decreasing energy (35,000 cm(-1)) and eventually exceeds it. Direct excitation of the repulsive triplet states is negligible except at photon energies E(ph) < 38,000 cm(-1). The main structure observed in the cross section is caused by excitation of the bound 2 (3)A" state, which is nearly degenerate with the 2 (1)A' state in the Franck-Condon region. The structure observed in the low energy tail of the spectrum is caused by excitation of quasi-bound bending vibrational states of the 2 (1)A' and 1 (1)A" electronic states. The absorption cross sections agree well with experimental data and the temperature dependence of the cross section is well reproduced.
在多参考组态相互作用理论水平上，计算了羰基硫的最低单重态和三重态的全局三维势能面和跃迁偶极矩函数。然后通过量子力学波包传播研究了第一紫外吸收带。激发排斥的 2(1)A'态对截面有主要贡献。在吸收峰（E(ph) ≈ 45,000 cm(-1))处，激发排斥的 1(1)A"态的强度约为 20 倍，但随着能量的降低（35,000 cm(-1))，它与 2(1)A'态吸收相当，最终超过了它。除了光子能量 E(ph) < 38,000 cm(-1)外，直接激发排斥三重态可以忽略不计。截面中观察到的主要结构是由束缚的 2(3)A"态激发引起的，该态在 Franck-Condon 区域与 2(1)A'态几乎简并。光谱低能尾部观察到的结构是由 2(1)A'和 1(1)A"电子态的准束缚弯曲振动态激发引起的。吸收截面与实验数据吻合较好，截面的温度依赖性也得到了很好的再现。
