Multistate vibronic interactions in difluorobenzene radical cations.: II.: Quantum dynamical simulations
Multistate vibronic interactions in difluorobenzene radical cations.: II.: Quantum dynamical simulations
复制标题
DOI：
10.1063/1.2958918
复制
发表时间：
2008-08-21
影响因子：
4.4
通讯作者：
Koeppel, Horst
中科院分区：
文献类型：
--
作者：
Faraji, Shirin;Meyer, H. -D.;Koeppel, Horst
用量子动力学从头算方法研究了三种二氟苯自由基阳离子的（X）over代字号-（D）over代字号电子态的多态振动动力学。本文采用了文[S]中的电子振动耦合方案和系统参数的从头算值。Faraji和H. Koppel，J.Chem.Phys.129，074310（2008）]。借助于多组态含时Hartree方法，通过波包传播进行了大量的计算。五个耦合电子势能面和10个（11个邻位异构体的情况下）振动自由度已包括在这些计算中。非绝热相互作用导致光电子谱包络的重构。超快的内部转换过程中的电子歧管的问题证明了强度的非绝热耦合效应和电子光谱的类似结果的补充。内部转换动力学的特征在于在飞秒到皮秒的时间尺度上电子布居逐步转移到最低电子态。发现三种异构体之间的差异与Meta异构体中（X）代字号-（A）代字号和（B）代字号-（C）代字号-（D）代字号状态（具有高能圆锥交叉）之间的相互作用较弱有关。这些研究结果的影响进行了讨论的定性理解的荧光动力学的氟苯自由基阳离子。(C)2008年美国物理学会。
The multistate vibronic dynamics in the (X) over tilde-(D) over tilde electronic states of all three difluorobenzene radical cations are investigated theoretically by an ab initio quantum dynamical approach. The vibronic coupling scheme and the ab initio values of the system parameters are adopted from Paper I [S. Faraji and H. Koppel, J. Chem. Phys. 129, 074310 (2008)]. Extensive calculations by wave-packet propagation have been performed with the aid of the multiconfiguration time-dependent Hartree method. Five coupled electronic potential energy surfaces and 10 (11 in the case of the orthoisomer) vibrational degrees of freedom have been included in these calculations. The nonadiabatic interactions lead to the restructuring of the photoelectron spectral envelopes. Ultrafast internal conversion processes within the electronic manifolds in question demonstrate the strength of the nonadiabatic coupling effects and complement the analogous findings for the electronic spectra. The internal conversion dynamics is characterized by a stepwise transfer of the electronic population to the lowest electronic state on a time scale of femtoseconds to picoseconds. A difference between the three isomers is found to be related to the weaker interaction between the sets of (X) over tilde-(A) over tilde and (B) over tilde-(C) over tilde-(D) over tilde states (with high-energy conical intersections) in the meta isomer, as compared to the other isomers. The implications of these findings for the qualitative understanding of the fluorescence dynamics of fluorinated benzene radical cations are discussed. (C) 2008 American Institute of Physics.