Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
J Am Chem Soc. 2014 Nov 19;136(46):16378-86. doi: 10.1021/ja509016a. Epub 2014 Nov 10.
We report multistate trajectory simulations, including coherence, decoherence, and multidimensional tunneling, of phenol photodissociation dynamics. The calculations are based on full-dimensional anchor-points reactive potential surfaces and state couplings fit to electronic structure calculations including dynamical correlation with an augmented correlation-consistent polarized valence double-ζ basis set. The calculations successfully reproduce the experimentally observed bimodal character of the total kinetic energy release spectra and confirm the interpretation of the most recent experiments that the photodissociation process is dominated by tunneling. Analysis of the trajectories uncovers an unexpected dissociation pathway for one quantum excitation of the O-H stretching mode of the S1 state, namely, tunneling in a coherent mixture of states starting in a smaller ROH (∼0.9-1.0 Å) region than has previously been invoked. The simulations also show that most trajectories do not pass close to the S1-S2 conical intersection (they have a minimum gap greater than 0.6 eV), they provide statistics on the out-of-plane angles at the locations of the minimum energy adiabatic gap, and they reveal information about which vibrational modes are most highly activated in the products.
我们报告了苯酚光解动力学的多态轨迹模拟，包括相干、退相干和多维隧穿。计算基于全维锚点反应势能面和状态耦合，这些耦合拟合了电子结构计算，包括与增强相关的动态关联，使用了扩充相关一致极化价双ζ基组。计算成功地再现了实验观察到的总动能释放谱的双峰特征，并证实了最近实验的解释，即光解过程主要由隧穿主导。轨迹分析揭示了 S1 态 O-H 伸缩模式的一个量子激发的意外解离途径，即在比以前提出的更小的 ROH（约 0.9-1.0 Å）区域开始的相干态混合中隧穿。模拟还表明，大多数轨迹不会靠近 S1-S2 锥形交叉（它们的最小间隙大于 0.6 eV），它们提供了在最低能量绝热间隙位置处的面外角度的统计信息，并揭示了有关产品中哪些振动模式被高度激活的信息。
