On-the-fly molecular dynamics study of the excited-state branching reaction of α-methyl-cis-stilbene

• Published in: Chemical physics Vol. 515; pp. 564 - 571
• Main Authors: Tsutsumi, Takuro, Harabuchi, Yu, Yamamoto, Rina, Maeda, Satoshi, Taketsugu, Tetsuya
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 14.11.2018
• Subjects: Excited-state dynamics; On-the-fly MD; Reaction pathways; Stilbene; Reaction pathways; On-the-fly MD; Excited-state dynamics; Stilbene
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2018.08.017

[Display omitted] The branching reaction of α-methyl-cis-stilbene (cis-mSB) into its trans-mSB and 4a,4b-dihydrophenanthrene (DHP) forms upon ππ∗ excitation was examined theoretically by exploring the excited-state potential energy surface and using on-the-fly molecular dynamics simulations at the spin-flip time-dependent density functional theory (SF-TDDFT) level of theory. The branching ratio of trajectories was calculated as DHP:twist = 11:29, where twist denotes a mid-region between the cis-form and trans-form, indicating that the trans-mSB is a dominant product. The branching mechanism was analyzed by comparison with the corresponding theoretical studies on stilbene (SB) and 1,1′-dimethyl-stilbene (dmSB). The present computations elucidate the origin of variations in the branching ratio in the photoreactions of cis-SB, cis-mSB, and cis-dmSB. We also found that, because of loss of the slow component of the decay to the ground state, cis-mSB shows a faster decay rate to the ground state than cis-SB and cis-dmSB.