科研之友
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摘要
A subtractive implementation of the QM/QM hybrid method for the description of photochemical reactions occurring in molecular crystals is presented and tested by applying it in a simulation study of the ultrafast intramolecular excited-state proton transfer reaction in the crystal form of 7-(2-pyridyl)-indole, an organic compound featuring an intramolecular hydrogen bond within a six-membered ring. By propagating molecular dynamics on the excited-state potential energy surface, a mean proton transfer time was calculated as 80 fs. The reaction mechanism is discussed in terms of three-dimensional reaction coordinate diagrams. Proton transfer was found to be barrierless and to be strongly coupled to vibrational modes of the photoexcited molecule that modulate the proton donor-acceptor distance. Some 300 fs after the initial photoexcitation, the excited state molecule reached an S-1/S-0 conical intersection through the mutual twist of the pyridyl and indolyl moieties.
- 出版日期2013-2
