Abstract:
Minimum-energy reaction paths and corresponding potential-energy profiles have been computed for the lowest excited states of the amino form of 9H-adenine. Complete-active- space self-consistent-field (CASSCF) and density functional theory (DFT) methods have been employed. The potential-energy function of the lowest 1πσ* state, nominally a 3s Rydberg state, is found to be dissociative with respect to the stretching of the NH bond length of the azine group. The 1πσ* potential-energy function intersects not only those of the 1ππ* and 1 nπ* excited states, but also that of the electronic ground state. The 1ππ*- 1πσ* and 1πσ*-S0 intersections are converted into conical intersections when the out-of-plane motion of the active hydrogen atom is taken into account. It is argued that the predissociation of the 1ππ* and 1 nπ* states by the 1πσ* state and the conical intersection of the 1πσ* state with the S0 state provide the mechanism for the ultrafast radiationless deactivation of the excited singlet states of adenine.
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Received 7 May 2002 Published online 13 September 2002
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Sobolewski, A., Domcke, W. On the mechanism of nonradiative decay of DNA bases: ab initio and TDDFT results for the excited states of 9H-adenine. Eur. Phys. J. D 20, 369–374 (2002). https://doi.org/10.1140/epjd/e2002-00164-5
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DOI: https://doi.org/10.1140/epjd/e2002-00164-5