DNA分子链的电子局域性质及电导的研究  

The localized properties of electronic states and conductivity of DNA sequence

作　　者：刘小良[1] 徐慧[1] 马松山[1] 邓超生[1] 郭爱敏[1] 

机构地区：[1]中南大学物理科学与技术学院,长沙410083

出　　处：《物理学报》2006年第10期5562-5567,共6页Acta Physica Sinica

基　　金：湖南省自然科学基金(批准号:05JJ40135);中南大学文理研究基金(批准号:0601052)资助的课题.~~

摘　　要：将一维随机二元固体模型应用于DNA分子链,利用传输矩阵方法来研究系统电子态的局域性质并进而讨论系统的导电性质.对一个链长为50000个碱基对的DNA序列,数值分析了局域长度和电导随碱基对的摩尔百分数、本征能量和无序度的变化关系.结果表明,系统的局域长度和电导强烈地依赖于能量,在能带中心部分局域长度大于边沿部分.无序度也在一定程度上影响着局域长度,双方成反向变化的关系.对有限长度的DNA分子链,局域长度体现出明显的对碱基对摩尔百分数的依赖关系,对正常成分比例的随机DNA序列,在所有能量范围内系统的态都是局域的,系统的电导很小,系统呈现绝缘体行为.仅当一种碱基对在序列中所占比例很小时,系统中可以发现与特定分立能量值相对应的“扩展态”存在,处在这些态下的系统有较大的电导,但这些扩展态是不稳定的,在热力学极限之下会消失.According to the tight-binding model of the single electron, we establish a one-dimensional random binary solid model for DNA molecules. Using the transfer-matrix approach, we calculate numerically the localization length and the conductivity of a DNA sequence with 50000 nucleotides base pairs. The results show that the random DNA sequence is an insulator with very small conductivity, that the localization length and conductivity strongly depend on energies, and there exist greater localization lengths at the band center than at the band edge, which implies there is higher conductivity at the band center. The results also show the localization lengths are affected by disorder degrees to some extent and decrease with the increasing of the degree of disorder for all energies. Especially with finite-size DNA sequence, the localization length and conductivity have obvious effect on nucleotide base pairs＇ mol percentage.

关 键 词：DNA分子链 电子局域 局域长度 电导 

分 类 号：Q523[生物学—生物化学]