DNA二聚体的多电荷转移和捕获
Multiple-charge transfer and trapping in DNA dimers
摘要：
我们使用模型哈密顿方法研究了DNA碱基对二聚体中一个和两个过剩电荷的电荷转移特性。电子部分包括对角和非对角库仑矩阵元，例如相关跳跃和键-键相互作用，其最近由Starikov [E. B.斯塔里科夫菲尔Mag. Lett. { \bf 83}，699（2003）]。电子自由度耦合到作为耗散环境的欧姆或超欧姆浴。我们采用数值重整化群方法在核隧穿制度和比较的结果Marcus理论的热激活制度。对于实际参数，在两个过量电子的子空间中至少一个电荷从供体转移到受体的速率显著超过单个电荷扇区中的速率。此外，库仑矩阵元的动力学的强烈影响。我们发现顺序和对转移，以及一个政权，两个收费保持自陷。在GC-GC二聚体中，当位间库仑矩阵元之差等于重组能时，转移速率达到最大值。在欧姆浴中，AT-AT中的两个过剩电子的电荷转移被完全抑制，而在超欧姆浴中，电荷转移被阻尼相干电子对振荡所取代。有限的键-键相互作用$W$改变了转移速率：当有效库仑排斥超过重组能（反转状态）时，它作为$W$的函数增加，并且对于较小的库仑排斥减小。
英文摘要：
We investigate the charge transfer characteristics of one and two excess charges in a DNA base-pair dimer using a model Hamiltonian approach. The electron part comprises diagonal and off-diagonal Coulomb matrix elements such a correlated hopping and the bond-bond interaction, which were recently calculated by Starikov [E. B. Starikov, Phil. Mag. Lett. {\bf 83}, 699 (2003)] for different DNA dimers. The electronic degrees of freedom are coupled to an ohmic or a super-ohmic bath serving as dissipative environment. We employ the numerical renormalization group method in the nuclear tunneling regime and compare the results to Marcus theory for the thermal activation regime. For realistic parameters, the rate that at least one charge is transferred from the donor to the acceptor in the subspace of two excess electrons significantly exceeds the rate in the single charge sector. Moreover, the dynamics is strongly influenced by the Coulomb matrix elements. We find sequential and pair transfer as well as a regime where both charges remain self-trapped. The transfer rate reaches its maximum when the difference of the on-site and inter-site Coulomb matrix element is equal to the reorganization energy which is the case in a GC-GC dimer. Charge transfer is completely suppressed for two excess electrons in AT-AT in an ohmic bath and replaced by damped coherent electron-pair oscillations in a super-ohmic bath. A finite bond-bond interaction $W$ alters the transfer rate: it increases as function of $W$ when the effective Coulomb repulsion exceeds the reorganization energy (inverted regime) and decreases for smaller Coulomb repulsion.
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