Ab Initio Multiple Spawning Photochemical Dynamics of DMABN Using GPUs

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• 作者：Basile F. E. Curchod ; Aaron Sisto ; Todd J. Martínez
• 刊名：Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：265-276
• 全文大小：681K
• ISSN：1520-5215

文摘

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 S₂ (the initially populated bright state) to S₁ 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 S₁ 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 (S₁).