Full dimensional quantum-mechanical simulations for the vibronic dynamics of difluorobenzene radical cation isomers using the multilayer multiconfiguration time-dependent Hartree method.
Full dimensional quantum-mechanical simulations for the vibronic dynamics of difluorobenzene radical cation isomers using the multilayer multiconfiguration time-dependent Hartree method.
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DOI：
10.1063/1.4755372
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发表时间：
2012-10
期刊：
影响因子：
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通讯作者：
Qingyong Meng;S. Faraji;O. Vendrell;H. Meyer
中科院分区：
文献类型：
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作者：
Qingyong Meng;S. Faraji;O. Vendrell;H. Meyer
采用Heidelberg MCTDH软件包，采用从头算多态多模电子振动耦合哈密顿（MMVCH）模型，对三种二氟苯阳离子异构体在五个最低电子态的动力学行为进行了全维多层多组态含时Hartree（ML-MCTDH）计算.同样的动力学问题，但处理与MCTDH计划和使用降维从头算MMVCH模型，以前已报道[S。法拉吉，H. D. Meyer和H. Köppel，“二氟苯自由基阳离子中的多态振动相互作用。129，074311（2008）]。为了便于与降维结果进行比较，还进行了11 D或10 D ML-MCTDH计算。进行广泛的ML-MCTDH测试计算以找到合适的ML-MCTDH波函数结构（ML树），并且仔细检查ML-MCTDH计算的收敛性以确保准确的结果。基于合适的ML树，模拟分析了光电子（PE）谱和质量分析阈值电离（MATI）谱，并与相应的实验谱进行了比较。由于其对大型系统的有效模拟能力，ML-MCTDH计算节省了大量的中央处理单元（CPU）时间，即使当使用降维MMVCH时，即，与相应的MCTDH计算中相同的简化模型。通过全维ML-MCTDH计算对实验PE谱进行模拟，再现了源自不同电子态的主峰。与降维计算相比，该协议得到了改善。不幸的是，实验PE光谱不是很好地解决。因此，我们比较我们的计算另外与高分辨率的MATI光谱，然而，这是只适用于X射线状态。基于一系列的ML-MCTDH模拟与较长的传播时间的X射线，一些振动模式，包括基本的，它们的组合，和泛音进行了模拟和分配通过比较与实验指定和从头算频率。实验和全维ML-MCTDH结果之间的良好相关性表明ML-MCTDH是准确的，非常有效的，从头算MMVCH模型是非常适合ML-MCTDH计算。
Full dimensional multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) calculations of the dynamics of the three difluorobenzene cationic isomers in five lowest-lying doublet electronic states using the ab initio multistate multimode vibronic coupling Hamiltonian (MMVCH) model are carried out using the Heidelberg MCTDH package. The same dynamical problems, but treated with the MCTDH scheme and using a reduced dimensional ab initio MMVCH model, have been previously reported [S. Faraji, H.-D. Meyer, and H. Köppel, "Multistate vibronic interactions in difluorobenzene radical cations. II Quantum dynamical simulations," J. Chem. Phys. 129, 074311 (2008)]. For easy comparison with the reduced dimensional results, 11D or 10D ML-MCTDH calculations are also performed. Extensive ML-MCTDH test calculations are performed to find appropriate ML-MCTDH wavefunction structures (ML-trees), and the convergence of the ML-MCTDH calculations are carefully checked to ensure accurate results. Based on the appropriate ML-trees, the photoelectron (PE) spectrum and the mass analyzed threshold ionization (MATI) spectrum are simulated, analyzed, and compared with corresponding experimental spectra. Because of its efficient simulation capability for large systems, ML-MCTDH calculations save a considerable amount of central processing unit (CPU)-time, even when a reduced dimensional MMVCH is used, i.e., the same reduced model as in the corresponding MCTDH calculations. Simulations of the experimental PE spectra by full dimensional ML-MCTDH calculations reproduced main peaks, which originate from different electronic states. The agreement is improved as compared to the reduced dimensionality calculations. Unfortunately, the experimental PE spectra are not very well resolved. Therefore, we compare our calculations additionally with highly resolved MATI spectra, which, however, are only available for the X̃ state. Based on a series of ML-MCTDH simulations with longer propagation time for X̃, a number of vibrational modes, including fundamentals, their combinations, and overtones are simulated and assigned by comparing with the experimental assignments and the ab initio frequencies. Excellent correlation between the experimental and full dimensional ML-MCTDH results show that ML-MCTDH is accurate and very efficient and that the ab initio MMVCH model is very suitable for ML-MCTDH calculations.