Photodynamical simulations of cytosine: characterization of the ultrafast bi-exponential UV deactivation

0364575 - ÚOCHB 2012 RIV GB eng J - Journal Article
Barbatti, M. - Aquino, A. J. A. - Szymczak, J. J. - Nachtigallová, Dana - Lischka, H.
Photodynamical simulations of cytosine: characterization of the ultrafast bi-exponential UV deactivation.
Physical Chemistry Chemical Physics. Roč. 13, č. 13 (2011), s. 6145-6155. ISSN 1463-9076. E-ISSN 1463-9084
R&D Projects: GA MŠMT LC512
Institutional research plan: CEZ:AV0Z40550506
Keywords : initio calculations * excited states * nucleic acids * photodynamics
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.573, year: 2011

Deactivation of UV-excited cytosine is investigated by non-adiabatic dynamics simulations, optimization of conical intersections, and determination of reaction paths. Quantum chemical calculations are performed up to the MR-CISD level. Dynamics simulations were performed at multiconfigurational level with the surface hopping method including four electronic states. The results show the activation of four distinct reaction pathways at two different subpicosecond time scales and involving three different conical intersections. Most trajectories relax to a minimum of the S1 state and deactivate with a time constant of 0.69 ps mainly through a semi-planar conical intersection along the no.pi.* surface. A minor fraction deactivate along .pi.pi.* regions of the S1 surface. Sixteen percent of trajectories do not relax to the minimum and deactivate with a time constant of only 13 fs.
Permanent Link: http://hdl.handle.net/11104/0200025