Vadhel Sagar, Jani Tejas, Shastri Aparna, Pothodichackra Vinodkumar, Vinodkumar Minaxi
V.P. & R.P.T.P. Science College, Vallabh Vidyanagar 388120, Gujarat, India.
Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
J Phys Chem A. 2022 Nov 10;126(44):8136-8155. doi: 10.1021/acs.jpca.2c05186. Epub 2022 Oct 26.
We report here theoretical investigations on structural, spectroscopic, and electron scattering for acrylonitrile (CHCHCN), a molecule of importance in astrochemistry as well as the chemical industry. Quantum chemical calculations for ground and excited states are performed using density functional theory (DFT) and time-dependent-DFT methods, respectively. The results of geometry optimization and vibrational frequencies agree well with data available in the literature, while vertical excited singlet-state energies are extended to higher excited states as compared to earlier studies, including Rydberg and valence excitations. Quantum defect analysis and comparison of the theoretically predicted energies with earlier reported experimental works led to the confirmation of some spectral assignments and the revision of a few assignments. Vibrational frequencies calculated for the cationic ground state are used to tentatively assign vibrational bands appearing along with the Rydberg transitions. Triplet excited-state energies for which no data is available in the literature are reported here for the first time. Low-energy (0.1 to 20 eV) electron scattering calculations are performed using the R-matrix method. Several types of resonances are predicted in the energy-dependent elastic cross-section, most of which are in good agreement with earlier experimental or theoretical works, while a few new resonances are found above 6 eV. Additionally, calculations of eigenphase sum, differential, momentum transfer, electronic excitation, ionization, and total cross-sections are being reported for the first time. This work represents a comprehensive theoretical study of the electronically excited states as well as low-energy electron scattering of acrylonitrile, which would be useful for understanding its chemistry in the interstellar medium as well as industrial applications.
我们在此报告对丙烯腈（CHCHCN）的结构、光谱和电子散射的理论研究，丙烯腈是天体化学以及化学工业中一种重要的分子。分别使用密度泛函理论（DFT）和含时密度泛函理论方法对基态和激发态进行量子化学计算。几何优化和振动频率的结果与文献中的数据吻合良好，而与早期研究相比，垂直激发单重态能量扩展到了更高的激发态，包括里德堡激发和价电子激发。量子缺陷分析以及将理论预测能量与早期报道的实验工作进行比较，使得一些光谱归属得到确认，同时对一些归属进行了修正。计算得到的阳离子基态振动频率用于初步归属伴随里德堡跃迁出现的振动谱带。本文首次报道了文献中尚无数据的三重态激发态能量。使用R矩阵方法进行低能（0.1至20电子伏特）电子散射计算。在能量依赖的弹性截面中预测了几种类型的共振，其中大多数与早期的实验或理论工作吻合良好，同时在6电子伏特以上发现了一些新的共振。此外，首次报道了本征相和、微分、动量转移、电子激发、电离和总截面的计算结果。这项工作代表了对丙烯腈电子激发态以及低能电子散射的全面理论研究，这对于理解其在星际介质中的化学性质以及工业应用将是有用的。
