First Principles Dynamics of Photoexcited DNA and RNA Bases
- Department of Chemistry, Beckman Institute, and Center for Biophysics and Computational Biology University of Illinois, Urbana, Illinois 61801 (United States)
The reaction dynamics of excited electronic states in nucleic acid bases is a key process in DNA photodamage. Recent ultrafast spectroscopy experiments have shown multi-component decays of excited uracil and thymine, tentatively assigned to nonadiabatic transitions involving multiple electronic states. Using both quantum chemistry and first principles quantum molecular dynamics methods we show that a true minimum on the bright S{sub 2} electronic state is responsible for the first step which occurs on a femtosecond timescale. Thus the observed femtosecond decay does not correspond to surface crossing as previously thought. We suggest that subsequent barrier crossing to the minimal energy S{sub 2}/S{sub 1} conical intersection is responsible for the picosecond decay.
- OSTI ID:
- 21043528
- Journal Information:
- AIP Conference Proceedings, Vol. 963, Issue 2; Conference: ICCMSE 2007: International conference on computational methods in science and engineering, Corfu (Greece), 25-30 Sep 2007; Other Information: DOI: 10.1063/1.2836045; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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