The Charge-Transfer States in a Stacked Nucleobase Dimer Complex: A Benchmark study

0364672 - ÚOCHB 2012 RIV US eng J - Journal Article
Aquino, A. J. A. - Nachtigallová, Dana - Hobza, Pavel - Truhlar, D. G. - Hättig, Ch. - Lischka, Hans
The Charge-Transfer States in a Stacked Nucleobase Dimer Complex: A Benchmark study.
Journal of Computational Chemistry. Roč. 32, č. 7 (2011), s. 1217-1227. ISSN 0192-8651. E-ISSN 1096-987X
R&D Projects: GA MŠMT LC512
Grant - others:NSF(US) CHE09-56776
Institutional research plan: CEZ:AV0Z40550506
Keywords : charge transfer * excited states * coupled cluster * DFT * stacked nucleobases
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 4.583, year: 2011

Electronic singlet excitations of stacked adenine–thymine (AT) and guanine–cytosine (GC) complexes have been investigated with respect to local excitation and charge-transfer (CT) characters. Potential energy curves for rigid displacement of the nucleobases have been computed to establish the distance dependence of the CT states. ADC(2) method served as reference approach for comparison to a selected set of density functionals used within the TD-DFT. Particular attention was dedicated to the performance of the recently developed family of M06 functionals. The calculations for the stacked complexes show that at the ADC(2) level, the lowest CT state is S6 for the AT and as S4 for the GC pair. At the reference geometry, the actual charge transferred is found to be 0.73 e for AT. In case of GC, this amount is much smaller (0.17 e). With increasing separation of the two nucleobases, the CT state is strongly destabilized. The M06-2X version provides a relatively good reproduction of the ADC(2) results. It avoids the serious overstabilization and overcrowding of the spectrum found with the B3LYP functional. On the other hand, M06-HF destabilizes the CT state too strongly.
Permanent Link: http://hdl.handle.net/11104/0200095