Quantum Transport in DNA-based molecular wires: Towards a realistic description of charge transport and dynamics in complex molecular systems

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The project main goal is to theoretically investigate the interplay between quantum transport (coherent and incoherent), disorder and stretching effects in DNA-based molecular wires, which are the focus of recent experimental work. The complexity of this issue makes necessary to use both density functional theory and model Hamiltonian approaches. We plan to proceed along the following lines: (i) Perform density-functional-based calculations of short DMA oligomers with different base sequences, in different environments as well as on stretched oligomers, in order to gain information about the electronic structure of the base pairs, their mutual interaction and the coupling with the environment; (ii) Investigate the mechanisms leading to polaron formation and its stability under different conditions (base sequence, environment) by a combined density-functional-based molecular dynamics approach; (iii) Formulate effective tight-binding Hamiltonians to minimally describe the electronic structure of DNA wires with arbitrary lengths, including the effects of an environment, and of internal vibrational degrees of freedom. The Hamiltonian wilt be parametrized by the density functional calculations of points (i) and (ii); (iv) Study nonequilibrium quantum transport in the previous model Hamiltonians. We will use Keldysh Green function techniques to describe the nonequilibrium regime. The use of the mentioned techniques will shed new light on ongoing experiments addressing the influence of disorder, as generated by biologically relevant base pair compositions, DNA-stretching, and structural fluctuations.