Rani Vadala Jhansi, Kanakati Arun Kumar, Mahapatra S
School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
J Chem Phys. 2024 Oct 14;161(14). doi: 10.1063/5.0222242.
Multi-dimensional quantum mechanical simulations are carried out to understand the multi-state and multi-mode vibronic interactions in the first six low-lying viz., X̃2B1, Ã2A1, B̃2B2, C̃2A2, D̃2A1, and Ẽ2B1 electronic states of c-C2H4O·+. Vibronic coupling theory is applied to study interactions among electronic states using symmetry selection rules. A model 6 × 6 diabatic electronic Hamiltonian is constructed. The parameters of the diabatic Hamiltonian are estimated by performing extensive ab initio electronic structure calculations, using the EOM-IP-CCSD method. The nuclear dynamics calculations are performed with both time-independent and time-dependent quantum mechanical methods. The calculated vibronic structures of six electronic states are found to be in excellent agreement with the available experimental findings. Progressions found in the theoretical spectrum are assigned in terms of vibrational modes. It is found that extremely strong vibronic interactions among the X̃2B1-Ã2A1, B̃2B2-C̃2A2, and D̃2A1-Ẽ2B1 electronic states results into highly overlapping vibronic bands due to multiple multi-state conical intersections. The impact of associated nonadiabatic effects on the vibronic structure and dynamics of the mentioned electronic states is examined at length. Interesting comparison is made with the results obtained for the isomeric acetaldehyde radical cation.
进行多维量子力学模拟，以了解环丙二酮阳离子（c-C2H4O·+）前六个低能电子态，即X̃2B1、Ã2A1、B̃2B2、C̃2A2、D̃2A1和Ẽ2B1中的多态和多模振子-电子相互作用。应用振子-电子耦合理论，利用对称选择规则研究电子态之间的相互作用。构建了一个6×6的非绝热电子哈密顿量模型。通过使用EOM-IP-CCSD方法进行广泛的从头算电子结构计算，估算了非绝热哈密顿量的参数。使用与时间无关和与时间有关的量子力学方法进行核动力学计算。发现六个电子态的计算振子-电子结构与现有的实验结果非常吻合。根据振动模式对理论光谱中发现的跃迁进行了归属。发现X̃2B1-Ã2A1、B̃2B2-C̃2A2和D̃2A1-Ẽ2B1电子态之间极其强烈的振子-电子相互作用，由于多个多态锥形交叉导致振子-电子能带高度重叠。详细研究了相关非绝热效应对上述电子态的振子-电子结构和动力学的影响。与同分异构的乙醛自由基阳离子得到的结果进行了有趣的比较。
