Charge transfer in DNA. Sensitivity of electronic couplings to conformational changesDedicated to Professor F. Dörr on the occasion of his 80th birthday.

Stable Valence Anions of Nucleic Acid Bases and DNA Strand Breaks Induced by Low Energy Electrons

“…from microseconds to several hours) than that required for non-adiabatic ET to be completed. Furthermore, several studies concerning hole transfer in DNA, which do proceed in nonadiabatic manner [30] demonstrated that the rate of charge transfer is strongly modified by the conformational changes of the biopolymer [31,32]. Hence, the dynamics of DNA might be another factor which could hinder the ET process assumed by the Simon's group [29] and the others [1,2].…”

Inelastic quantum transport in a ladder model: Implications for DNA conduction and comparison to experiments on suspended DNA oligomers

“…Though calculations 23,46 show that the interstrand hopping is usually very small, ϳ few meV, we do not consider the hopping integrals as bare tight-binding parameters but as effective ones, thus keeping some freedom in the choice of their specific values. Electronic correlations 41 or structural fluctuations mediated by the coupling to other vibrational degrees of freedom 47 can lead to a strong renormalization of the bare electronic coupling. The interaction with the electronic reservoirs will be described in the most simple way by invoking the wideband approximation, i.e., neglecting the energy dependence of the leads' self-energies ͑see below͒.…”

π−πorbital resonance in twisting duplex DNA: Dynamical phyllotaxis and electronic structure effects

“…Accordingly, some complementary approaches would be welcome in order to get a more detailed picture of the optimal DNA stack configurations. 5,6,11 Spurred by these results, in the present work we shall study the physical role of collective twist motions of the bps which occur in a synchronized manner, giving rise to the emergence of helicoidal standing waves in the DNA duplex. The resulting structural patterns will be described in the framework of dynamical phyllotaxis, by focusing on the presence of long-range spatial correlation effects mediated by twist phonons coupling.…”

“…5,10 Thus, depending on the DNA sequence composition, its length and effective temperature, reported transfer integral values can vary over a relatively broad interval, ranging from t = 0.01 to t = 0.4 eV. 6,[11][12][13][14][15][16][17][18][19][20][21] These figures imply charge migration time scales within the range ប / t Ӎ 2 -66 fs for coherent tunneling. Nevertheless, femtosecond spectroscopy experiments aimed at determining the rates of DNA charge-transport processes unveiled a two-step decay process with characteristic time scales of 5-10 and 75 ps, respectively, 22,23 which cannot be accounted for in terms of coherent tunneling processes alone.…”

“…Accordingly, the electronic coupling between nucleobases is very sensitive to structural fluctuations and the Condon approximation is rather limited. [6][7][8] Making use of molecular-dynamics calculations it was shown that the standard deviation of the nucleobases coupling is much larger than its average value. This result indicates that charge transport in DNA preferentially occurs in specific conformations, which may considerably deviate from the canonical B-DNA structure.…”