Alfalah S, Belz S, Deeb O, Leibscher M, Manz J, Zilberg S
Faculty of Pharmacy, Al-Quds University, POB 20002, Palestine.
J Chem Phys. 2009 Mar 28;130(12):124318. doi: 10.1063/1.3089546.
In this study, we investigate the photoinduced nonadiabatic dynamics of para- and ortho-fulvene by a combination of quantum chemical ab initio calculations and quantum dynamical simulations. We explore the competition between two different pathways, the photoisomerization and radiationless decay via a conical intersection (CI) at planar configuration. For this purpose, we extend a previous two-dimensional model which included the molecular torsion and the antisymmetric stretch as a coupling mode [Grohmann et al., Chem. Phys. 338, 252 (2007)] to a three-dimensional model, taking into account also the symmetric stretch as additional vibrational mode. Quantum dynamical simulations show that upon excitation with a single short laser pulse, the mode selective motion along the symmetric stretch drives the system to the CI, followed by radiationless decay before photoisomerization of fulvene can take place, thus confirming previous semiclassical calculations [Bearpark et al., J. Am. Chem. Soc. 118, 5253 (1996)]. Moreover, we show that the competition between photoisomerization and radiationless decay at a planar geometry depends on the nonadiabatic coupling strength.
在本研究中，我们通过量子化学从头算计算和量子动力学模拟相结合的方法，研究了对-富烯和邻-富烯的光诱导非绝热动力学。我们探讨了两种不同途径之间的竞争，即光异构化和通过平面构型处的锥形交叉点（CI）的无辐射衰变。为此，我们将先前的二维模型（该模型将分子扭转和反对称拉伸作为耦合模式[格罗曼等人，《化学物理》338, 252 (2007)]）扩展为三维模型，还将对称拉伸作为额外的振动模式考虑在内。量子动力学模拟表明，用单个短激光脉冲激发时，沿对称拉伸的模式选择性运动将系统驱动至锥形交叉点，随后在富烯发生光异构化之前发生无辐射衰变，从而证实了先前的半经典计算结果[贝尔帕克等人，《美国化学会志》118, 5253 (1996)]。此外，我们表明平面几何构型处光异构化和无辐射衰变之间的竞争取决于非绝热耦合强度。
