An efficient molecular orbital approach for self-consistent calculations of molecular junctions.
An efficient molecular orbital approach for self-consistent calculations of molecular junctions.
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DOI：
10.1063/1.2388264
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发表时间：
2006-11
期刊：
影响因子：
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通讯作者：
Hisao Nakamura;K. Yamashita
中科院分区：
文献类型：
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作者：
Hisao Nakamura;K. Yamashita
为了模拟通过分子结的电子传输，我们提出了一种使用从头算起的自洽非平衡格林函数理论与密度泛函理论相结合的有效方法。由于其灵活性，我们采用了接近扩展分子方法的模型，但通过与格林函数相同的从头计算水平的系统程序，改进了与分子表面耦合和长程势相关的问题。由此产生的算法涉及三个主要步骤：（i）构建嵌入势； (ii) 格林函数在分子轨道基础上的微扰展开； (iii) 通过将分子轨道空间分为非活性空间、活性空间和虚空间来截断分子轨道空间。上述过程直接减小了格林函数的矩阵大小以实现自洽计算步骤，因此该算法适合应用于大分子系统。
To model electron transport through a molecular junction, we propose an efficient method using an ab initio self-consistent nonequilibrium Green's function theory combined with density functional theory. We have adopted a model close to the extended molecule approach, due to its flexibility, but have improved on the problems relating to molecule-surface couplings and the long-range potential via a systematic procedure for the same ab initio level as that of Green's function. The resulting algorithm involves three main steps: (i) construction of the embedding potential; (ii) perturbation expansion of Green's function in the molecular orbital basis; and (iii) truncation of the molecular orbital space by separating it into inactive, active, and virtual spaces. The above procedures directly reduce the matrix size of Green's function for the self-consistent calculation step, and thus, the algorithm is suitable for application to large molecular systems.