共查询到18条相似文献,搜索用时 78 毫秒
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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 相似文献
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采用局域密度泛函理论和第一性原理的方法,计算四方结构和六角结构硅酸锌的平衡晶格常数、电子态密度和能带结构。计算结果表明,四方结构硅酸锌的平衡晶格常数为0.71048nm,六角结构为1.40877nm,两者与实验值的误差均在1%左右。态密度图显示,主要电子态分布在-7.18~0.00eV和2.79~10.50eV两个能量区域;同时,不同元素电子对导带和价带有不同贡献,其中氧的p态电子对价带顶贡献最大,锌的s态电子对导带底贡献最大。能带计算表明,四方与六角结构硅酸锌均为直接带隙半导体,禁带宽度分别为2.66,2.89eV。 相似文献
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电场对分子线电子结构的影响 总被引:6,自引:2,他引:4
从第一性原理出发,利用密度泛函理论计算了分子2-氨基-5-硝基-1,4-二乙炔基-4-苯硫醇基苯与金原子团形成的分子线的电子结构,从轨道、能级及吸附电子三个方面讨论了电场对分子线电子结构的影响.该工作将有利于未来纳米电子学器件的设计. 相似文献
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文章作者用磁镊与原子力显微镜研究了抗癌药物顺铂对单个DNA分子结构的影响.当顺铂浓度较低时,DNA链变得柔软,驻留长度从~52 nm显著缩短到~15 nm; 当顺铂浓度较高时, DNA表现出凝聚现象.基于单分子拉伸和原子力显微镜(AFM)成像两方面的实验结果,文章作者提出一个顺铂导致的DNA变软(softening)-成环(looping)-缩短(shortening)-凝聚(condensing)模型(简写为SLSC模型)来解释观察到的DNA凝聚,并认为通过远程交联使DNA形成小环结构是铂类抗癌药物作用的重要特征. 相似文献
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随着单分子操纵技术的发明与发展,人们已经可以对单个生物大分子施以力或力矩,并测量它们的物理性质,DNA单分子的力学实验表明,在分子尺度上理解生物大分子的生化过程,力与能量是同等重要的结构与功能参数。一个梯子模型被用来描述双链DNA的外力拉伸曲线,在这个模型中,DNA是由许多碱基对(梯子的横杆,横杆之间存在吸引势)连接两条聚核苷酸虫链(梯子的两侧)形成的高分子,利用路径积分法得出的理论曲线与实验曲线吻合得很好,对于单链DNA,用分立的杂化高分子链统计理论的母函数方法来计算其弹性行为,得出与实验相符合的外力引起的解链相变结果。此外,对于抑瘤蛋白p53识别序列DNA微环弹性进行分析,发现其弹性模量只是通常随机序列的三分之一。 相似文献
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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.
关键词:
DNA分子链
电子局域
局域长度
电导 相似文献
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《Physics letters. A》2019,383(17):2069-2075
By using density functional theory in combination with non-equilibrium Green's function method, we have investigated the spin-polarized electronic transport properties of four DNA base devices, namely, adenine (A), cytosine (C), guanine (G) and thymine (T). The results show the spin-polarized transport properties can be effectively regulated by adopting different bases, and thymine based device can exhibit high-efficiency spin-filtering, negative differential resistance, spin rectifying behaviors and switching effect by tuning the external magnetic field. We find that the variation in the degree of localization of the frontier molecular orbitals at different biases is responsible for these interesting phenomena. These effects can be explained by the spin-resolved transmission spectrum and the spatial distribution of molecular orbitals around the Fermi level. Our results suggest that thymine base holds great potential application in designing multi-functional spin molecular device. 相似文献
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首先用液流拉伸单分子DNA,使其吸附在修饰过的云母基片上.然后让二次液流沿着垂直于已拉伸的DNA的方向流过云母片,用原子力显微镜(AFM)观测,可见DNA单分子片段在基片上形成了一些纳米尺度的悬链线.提出一种“S悬桥”模型能定量地解释这一现象.该研究工作揭示,在DNA的单分子操作中,经典的弹性力学理论足以描述和控制DNA分子二维图形的形成
关键词:
DNA
单分子DNA操纵
原子力显微镜(AFM)
纳米悬链线 相似文献
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采用量子化学密度泛函理论方法在B3LYP/6-31G水平上对具有手性侧链的卟啉液晶分子进行几何结构优化,在此基础上使用含时密度泛函理论方法计算了分子第一激发态的电子垂直跃迁能,得到最大吸收波长λmax.计算表明,手性侧链取代基对λmax的影响不大,Zn络合导致最大吸收波长兰移,与实验结果一致. 相似文献
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X.-M. Wang H.-P. Zheng C.-J. Li 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(2):255-263
In order to get more reliable electronic structure of
protein in aqueous solution, it is necessary to construct a simple, easy-use
equivalent potential of water molecules for protein's electronic structure
calculation. The first-principles, all-electron, ab initio calculations have been
performed to construct the equivalent potential of water molecules for the
electronic structure of Cys. The process consists of three steps. First, the
electronic structure of the cluster containing Cys and water molecules is
calculated. Then, based on the structure, the electronic structure of Cys
with the potential of water molecules is calculated using the
self-consistent cluster-embedding method. Finally, the electronic structure
of Cys with the potential of dipoles is calculated. The dipoles are adjusted
so the electronic structure of Cys with the potential of dipoles is close to
that of water molecules. The calculations show that the major effect of
water molecules on Cys' electronic structure is lowering the occupied
electronic states by about 0.032 Ry, and broadening energy gap by 16%.
The effect of water molecules on the electronic structure of Cys can be
simulated by dipoles potential. 相似文献
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Using ab initio calculations based on density functional theory, an equivalent potential of water molecules for the electronic structure of Ala in solution has been obtained. The calculation process consists of three steps: first, the geometric structure of Ala + nH2O system is determined by searching for the lowest energy of the system using free cluster calculation method. Second, based on the geometric structure obtained, the electronic structure of Ala with the potential of water molecules is calculated using a self-consistent cluster-embedding method. Finally, after replacing water molecules with dipoles, the electronic structure of Ala with the potential of dipoles is calculated. The dipoles are adjusted so the electronic structure of Ala with the potential of dipoles is close to that of water molecules. The calculated results show that the main effect of water molecules is to raise the state for methyl CH3 by about 0.14 Ry, raising all other eigenvalues by about 0.059 Ry, and widening the energy gap by about 25%. In contrast, the replacement of water molecules by dipoles is comparatively efficient, showing that the effect of water molecules on the electronic structure of Ala can be simulated by a dipole potential, which would be a shortcut calculation. 相似文献