碱基对组分、电极位能及界面耦合对DNA分子I-V特性的影响

在紧束缚近似下,利用传输矩阵方法,计算研究了碱基对组分、金属电极位能及DNA分子与电极耦合强度对DNA分子I-V特征的影响.计算结果表明:由单一碱基对构成的DNA分子的饱和电流强度远大于由两种碱基对按一定组分随机分布的DNA分子的饱和电流强度,且当DNA分子中两种碱基对的含量相等时,其饱和电流强度最小.同时,富含C-G碱基对的DNA分子比富含A-T碱基对的DNA分子的电子输运能力大.金属电极位能对DNA分子电子输运的影响体现在两方面,当偏压较小时,电极位能具有阻碍电荷注入的效果,当偏压较大时

Base pairs composition,on-site energies of electrode and DNA-metal coupling effects on current-voltage characteristic of DNA molecule

Based on a tight-binding approximation and transfer matrix method, we investigated the effects of the composition of nucleotide base pairs, on-site energies of the electrode and DNA-metal coupling strength on the current-voltage characteristic. The results indicate that the saturation current of DNA molecule which is composed of one single kind of nucleotide base pair is much higher than that composed of two kinds of nucleotide base pair. Meanwhile, the DNA molecule which is rich in G-C base pairs has higher electronic transport ability. When the bias is low, the on-site energies of the electrode have the effect of impeding charge injection. On the other hand, when the bias is high, the on-site energies of the electrode have the effect of enhancing charge injection. In addition, we can find that a stronger DNA-metal coupling does not always result in a larger saturation current. When t_dm=t_d, there is a resonance injection, which is optimized for electron transport. When t_dm departs from t_d, the resonance injection is reduced, which lead to the stronger of DNA-metal coupling at the range of t_dm>t_d and the lower of saturation current of DNA.