A full-dimensional multilayer multiconfiguration time-dependent Hartree study on the ultraviolet absorption spectrum of formaldehyde oxide.
A full-dimensional multilayer multiconfiguration time-dependent Hartree study on the ultraviolet absorption spectrum of formaldehyde oxide.
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DOI：
10.1063/1.4896201
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
Qingyong Meng;H. Meyer
中科院分区：
文献类型：
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作者：
Qingyong Meng;H. Meyer
采用多层多组态含时Hartree(ML-MCTDH)方法，结合多态多模振动耦合哈密顿(MMVCH)模型，对最简单的Criegee中间体甲醛氧化物在5个低位单重态进行了全维(9D)量子动力学研究。然后通过自相关函数的傅里叶变换来模拟紫外(UV)光谱。MMVCH模型是基于广泛的MRCI(8e，8o)/aug-cc-pVTZ计算建立的。为了确保最终计算的快速收敛，进行了大量的ML-MCTDH测试计算，以找到合适的ML-MCTDH核波函数的多层分离(ML-树)，并对动力学计算进行了仔细的检查，以确保计算的良好收敛。为了比较计算效率，还使用相同的哈密顿量进行了标准的MCTDH模拟。比较了两种方法的计算结果，结果表明，即使对于目前不太大的体系(这里是9维)，ML-MCTDH计算也可以节省大量的计算资源，同时产生与MCTDH计算相同的谱。此外，本文的理论B̃(1)A‘←X̃(1)A’UV光谱带和相应的实验测量[J.M.Beams，F.Liu，L.Lu和M.I.Lester，J.Am.化学。SoC。20045-20048(2012年)；L.Sheps，J.Phys。化学。让我们来吧。4,4201-4205(2013)；Ting W.L.Ting，Y.-H.Chen，W.Chao，M.C.Smith，J.J.M.Lin，Phys.化学。化学。太棒了。16,10438-10443(2014年)]进行了讨论。据我们所知，这是第一次为该分子模拟的理论紫外光谱，包括超出绝热简谐近似的核运动。
Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjunction with the multistate multimode vibronic coupling Hamiltonian (MMVCH) model, we perform a full dimensional (9D) quantum dynamical study on the simplest Criegee intermediate, formaldehyde oxide, in five lower-lying singlet electronic states. The ultraviolet (UV) spectrum is then simulated by a Fourier transform of the auto-correlation function. The MMVCH model is built based on extensive MRCI(8e,8o)/aug-cc-pVTZ calculations. To ensure a fast convergence of the final calculations, a large number of ML-MCTDH test calculations is performed to find an appropriate multilayer separations (ML-trees) of the ML-MCTDH nuclear wave functions, and the dynamical calculations are carefully checked to ensure that the calculations are well converged. To compare the computational efficiency, standard MCTDH simulations using the same Hamiltonian are also performed. A comparison of the MCTDH and ML-MCTDH calculations shows that even for the present not-too-large system (9D here) the ML-MCTDH calculations can save a considerable amount of computational resources while producing identical spectra as the MCTDH calculations. Furthermore, the present theoretical B̃(1)A'←X̃(1)A' UV spectral band and the corresponding experimental measurements [J. M. Beames, F. Liu, L. Lu, and M. I. Lester, J. Am. Chem. Soc. 134, 20045-20048 (2012); L. Sheps, J. Phys. Chem. Lett. 4, 4201-4205 (2013); W.-L. Ting, Y.-H. Chen, W. Chao, M. C. Smith, and J. J.-M. Lin, Phys. Chem. Chem. Phys. 16, 10438-10443 (2014)] are discussed. To the best of our knowledge, this is the first theoretical UV spectrum simulated for this molecule including nuclear motion beyond an adiabatic harmonic approximation.