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

该项目的主要目标是从理论上研究基于dna的分子线中量子输运（相干和非相干）、无序和拉伸效应之间的相互作用，这是最近实验工作的重点。这个问题的复杂性使得有必要同时使用密度泛函理论和模型哈密顿方法。我们计划沿着以下路线进行：(i)对不同碱基序列的短DMA低聚物在不同环境下以及在拉伸低聚物上进行基于密度函数的计算，以获得有关碱基对的电子结构，它们之间的相互作用以及与环境的耦合的信息；采用基于密度-功能的分子动力学方法，研究极化子形成的机制及其在不同条件下（碱基序列、环境）的稳定性；（iii）制定有效的紧密结合哈密顿量，以最小限度地描述任意长度DNA导线的电子结构，包括环境和内部振动自由度的影响。哈密顿量将通过点(i)和点（ii）的密度泛函计算参数化；（iv）研究先前模型哈密顿量中的非平衡量子输运。我们将使用Keldysh Green函数技术来描述非平衡状态。上述技术的使用将为正在进行的解决由生物学相关碱基对组成、dna拉伸和结构波动产生的无序影响的实验提供新的思路。

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.