Curchod Basile F E, Sisto Aaron, Martínez Todd J
Department of Chemistry and the PULSE Institute, Stanford University , Stanford, California 94305, United States.
SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
J Phys Chem A. 2017 Jan 12;121(1):265-276. doi: 10.1021/acs.jpca.6b09962. Epub 2017 Jan 3.
The ultrafast decay dynamics of 4-(N,N-dimethylamino)benzonitrile (DMABN) following photoexcitation was studied with the ab initio multiple spawning (AIMS) method, combined with GPU-accelerated linear-response time-dependent density functional theory (LR-TDDFT). We validate the LR-TDDFT method for this case and then present a detailed analysis of the first ≈200 fs of DMABN excited-state dynamics. Almost complete nonadiabatic population transfer from S (the initially populated bright state) to S takes place in less than 50 fs, without significant torsion of the dimethylamino (DMA) group. Significant torsion of the DMA group is only observed after the nuclear wavepacket reaches S and acquires locally excited electronic character. Our results show that torsion of the DMA group is not prerequisite for nonadiabatic transitions in DMABN, although such motion is indeed relevant on the lowest excited state (S).
采用从头算多重产生（AIMS）方法，并结合GPU加速的线性响应含时密度泛函理论（LR-TDDFT），研究了4-（N，N-二甲基氨基）苯甲腈（DMABN）光激发后的超快衰减动力学。我们验证了该情况下的LR-TDDFT方法，然后对DMABN激发态动力学的前约200飞秒进行了详细分析。在不到50飞秒的时间内，几乎完全发生了从S（最初占据的亮态）到S的非绝热布居转移，而二甲基氨基（DMA）基团没有明显的扭转。只有在核波包到达S并获得局域激发电子特征后，才观察到DMA基团的明显扭转。我们的结果表明，DMA基团的扭转不是DMABN中非绝热跃迁的先决条件，尽管这种运动在最低激发态（S）上确实是相关的。
