Lehr Andreas, Gómez Sandra, Parkes Michael A, Worth Graham A
Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
University College London, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, UK.
Phys Chem Chem Phys. 2020 Nov 21;22(43):25272-25283. doi: 10.1039/d0cp04514d. Epub 2020 Nov 2.
The first two excitation bands below 7 eV in the electronic absorption spectrum of maleimide are investigated using a model Hamiltonian including four low-lying singlet excited states within the manifold of 24 vibrational modes. The role of non-adiabatic effects is studied and shines light on both the broad, inter-state coupling-dominated spectral band as well as the fine-structured, not-so-strong coupled band. Calculations have been performed using the Multiconfigurational Time-Dependent Hartree (MCTDH) wavepacket propagation method as well as its multilayer version (ML-MCTDH) using a quadratic vibronic coupling (QVC) Hamiltonian model where parameters are obtained from fitting adiabatic potential energy surfaces computed by ab initio methods. The quantum dynamics calculations provide information on the relaxation dynamics and the vibrational modes involved. Already with a low-order vibronic coupling model and only a few modes being considered, a quantitative agreement with the experimental spectrum is obtained. However, it is found that all modes need to be considered to get a full picture of the photo-excited relaxation dynamics of this molecule.
使用一个包含24个振动模式流形内的四个低能单重激发态的模型哈密顿量，研究了马来酰亚胺电子吸收光谱中低于7 eV的前两个激发带。研究了非绝热效应的作用，揭示了宽的、以态间耦合为主的光谱带以及精细结构的、耦合不太强的光谱带。使用多组态含时哈特里（MCTDH）波包传播方法及其多层版本（ML-MCTDH）进行了计算，采用二次电子振动耦合（QVC）哈密顿量模型，其中参数通过拟合从头算方法计算的绝热势能面获得。量子动力学计算提供了有关弛豫动力学和所涉及振动模式的信息。仅使用低阶电子振动耦合模型并仅考虑少数模式，就获得了与实验光谱的定量一致性。然而，发现需要考虑所有模式才能全面了解该分子的光激发弛豫动力学。
