Nonadiabatic Dynamics of Uracil: Population Split among Different Decay Mechanisms

0364303 - ÚOCHB 2012 RIV US eng J - Článek v odborném periodiku
Nachtigallová, Dana - Aquino, A. J. A. - Szymczak, J. J. - Barbatti, M. - Hobza, Pavel - Lischka, H.
Nonadiabatic Dynamics of Uracil: Population Split among Different Decay Mechanisms.
Journal of Physical Chemistry A. Roč. 115, č. 21 (2011), s. 5247-5255. ISSN 1089-5639. E-ISSN 1520-5215
Grant CEP: GA MŠMT LC512
Výzkumný záměr: CEZ:AV0Z40550506
Klíčová slova: ab initio calculations * excited states * nucleic acids * photodynamics
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 2.946, rok: 2011

Nonadiabatic dynamics simulations performed at the state-averaged CASSCF method are reported for uracil. The dominant mechanism is characterized by relaxation into the S(2) minimum of .pi.pi.* character followed by the relaxation to the S(1) minimum of n.pi. * character. This mechanism contributes to the slower relaxation with a decay constant larger than 1.5 ps, in good agreement with the long time constants experimentally observed. A minor fraction of trajectories decay to the ground state with a time constant of about 0.7 ps, which should be compared to the experimentally observed short constant. A contribution of the relaxation proceeding via a ring-opening conical intersection was also observed. The existence of these two latter channels together with a reduced long time constant is responsible for a significantly shorter lifetime of uracil compared to that of thymine.
Trvalý link: http://hdl.handle.net/11104/0006547