电子输运计算中电极自能矩阵的轮廓积分法
Contour integral method for obtaining the self-energy matrices of electrodes in electron transport calculations
摘要：
我们提出了一种有效的计算方法来评估电极的自能矩阵，以研究纳米系统中的弹道电子输运性质。为了减少大型系统中的高计算成本，基于Sakurai-Sugiura方法结合移位双共轭梯度法的轮廓积分特征值求解器被开发用于求解复波矢量的指数型特征值问题。该算法的一个显著特点是数值计算过程与传统的能带结构计算过程非常相似。我们实现了开发的方法的框架下的实空间高阶有限差分格式与非局部赝势。各种材料的数值试验验证了所提出的方法的鲁棒性，准确性和效率。作为该方法的一个例子，我们提出了电子输运性质的独立硅烯与线缺陷起源于反向屈曲相。
英文摘要：
We propose an efficient computational method for evaluating the self-energy matrices of electrodes to study ballistic electron transport properties in nanoscale systems. To reduce the high computational cost incurred in large systems, a contour integral eigensolver based on the Sakurai-Sugiura method combined with the shifted biconjugate gradient method is developed to solve exponential-type eigenvalue problem for complex wave vectors. A remarkable feature of the proposed algorithm is that the numerical procedure is very similar to that of conventional band structure calculations. We implement the developed method in the framework of the real-space higher-order finite difference scheme with nonlocal pseudopotentials. Numerical tests for a wide variety of materials validate the robustness, accuracy, and efficiency of the proposed method. As an illustration of the method, we present the electron transport property of the free-standing silicene with the line defect originating from the reversed buckled phases.
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