The singlet electronic states of pyrrole: a theoretical study by both ab initio multi-reference configuration interaction methods and time-dependent density functional theory and a reconsideration of the experimental VUV spectral data
The singlet electronic states of pyrrole: a theoretical study by both ab initio multi-reference configuration interaction methods and time-dependent density functional theory and a reconsideration of the experimental VUV spectral data
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吡咯的单线态电子态：从头算多参考构型相互作用方法和瞬态密度泛函理论的理论研究以及对实验 VUV 光谱数据的重新考虑
DOI：
10.1080/0026897031000108050
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发表时间：
2003
影响因子：
1.7
通讯作者：
P. Wilson
中科院分区：
文献类型：
--
作者：
M. Palmer;P. Wilson
采用多参考多根组态相互作用（CI）和含时密度泛函理论（DFT）方法，结合渐近修正的交换关联势，重新研究了吡咯分子的单重电子激发光谱.该方法使用三重zeta价+极化+ Rydberg（TZVPR）基组和比我们先前的CI研究中大得多的活性空间[Palmer，M. H、步行者岛C.的方法，客人，M。F.、1998，化学物理，238，179]。计算的垂直激发能，振子强度和电子电荷分布被用来表征和分配的价和里德堡激发态的能量范围为5-12 eV。与其他高层次的从头算研究，本方法进行了比较，包括基组和CI的大小的影响，并确定一些统计关系。与各种二阶微扰型方法（CASPT 2、CASPT 2-MS、ADC（2）和MRMP）相比，目前的CI垂直激发能通常与团簇型方法（尤其是CC 3）更接近。研究了杂化泛函发展中轨道交换势和乘性势对激发能的影响。CI和DFT方法之间的差异按B 97 -2 <B 97 -1 < HCTH < LDA的顺序变化。混合DFT和CI激发之间的差异最小化时，轨道交换的分数（π）位于约0.2-0.3的范围。里德堡和价型激发被认为是不太敏感的静态极化率，包括轨道交换或乘法潜力的混合功能的发展。为了让一个现实的评估性能的理论研究，吡咯的实验电子光谱的分配进行了详细讨论。以前的结论导致了里德堡s-和d-型状态的错误数量，而f-型状态以前被忽略了。一些激发从第二IP，这必须发生在5-10 eV的范围内，已被重新分配在光的其他光谱状态和量子缺陷之间的已知的小差异。目前迫切需要对吡咯及其相关分子进行更高分辨率的研究。
The singlet electronic excitation spectrum of pyrrole has been reinvestigated by both multi-reference multi-root configuration interaction (CI) calculations and time-dependent density functional theory (DFT) with asymptotically corrected exchange-correlation potentials. The methods used a triple zeta valence + polarization + Rydberg (TZVPR) basis set and a much larger active space than in our previous CI study [Palmer, M. H., Walker, I. C., and Guest, M. F., 1998, Chem. Phys., 238, 179]. Computed vertical excitation energies, oscillator strengths and electronic charge distributions were used to characterize and assign the valence and Rydberg excited states over an energy range of 5–12 eV. A comparison of the present methods with other high-level ab initio studies has been made, including the effects of basis sets and size of CI, and some statistical relationships determined. The present CI vertical excitation energies are generally in closer agreement with the cluster-type methods, especially CC3, than to the various second-order perturbation-type methods (CASPT2, CASPT2-MS, ADC(2) and MRMP). The influence on the excitation energies from exact orbital exchange and multiplicative potentials in hybrid functional development has been investigated. Differences between the CI and the DFT methods vary in the order B97-2 < B97-1 < HCTH < LDA. The differences between hybrid DFT and CI excitations are minimized when the fraction of orbital exchange (ξ) lies in the approximate range 0.2–0.3. The Rydberg and valence-type excitations are seen to be less sensitive than the static polarizability to the inclusion of orbital exchange or multiplicative potentials in hybrid functional development. In order to allow a realistic assessment of the performance of the theoretical studies, the assignment of the experimental electronic spectrum of pyrrole is discussed in detail. Previous conclusions have led to incorrect numbers of Rydberg s- and d-type states, while f-type states have previously been ignored. Some excitations from the second IP, which must occur in the 5–10 eV range, have been reassigned in light of the known small differences between other spectroscopic states and quantum defects. There is an urgent need for higher-resolution studies of pyrrole and related molecules.