Assessment of approximations in nonequilibrium Green’s function theory
Assessment of approximations in nonequilibrium Green’s function theory
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非平衡格林函数理论中近似值的评估
DOI：
10.1103/physrevb.83.195304
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发表时间：
2011
影响因子：
3.7
通讯作者：
P. Vogl
中科院分区：
文献类型：
--
作者：
T. Kubis;P. Vogl
提出了开放式半导体纳米器件中固定载流子动力学的非平衡格林函数（NEGF）方法，其中包括所有相关的非相干散射机制。开发了一致的先导模型，确保所有可观测值都能反映器件的内在特性。通过将电荷自洽计算限制为通过异质结构的垂直传输，可以非常准确地确定格林函数和自能。这使我们能够详细评估许多常用的近似，例如弹道导程、戴森和凯尔迪什方程的解耦、截断或动量平均自能以及 NEGF 形式中的局部自能，并研究电阻器中的扩散传输等极限情况。精确和近似 NEGF 计算的比较说明了常见近似值的物理含义和有效性，并提出了数值有效的简化。
A nonequilibrium Green's function (NEGF) method for stationary carrier dynamics in open semiconductor nanodevices is presented that includes all relevant incoherent scattering mechanisms. A consistent lead model is developed that ensures all observables to reflect intrinsic device properties. By restricting the charge self-consistent calculations to vertical transport through heterostructures, the Green's functions and self-energies can be determined very accurately. This allows us to assess many commonly used approximations, such as ballistic leads, decoupling of Dyson's and Keldysh's equations, truncated or momentum-averaged self-energies, and local self-energies in the NEGF formalism in detail, and to study limiting cases such as diffusive transport in resistors. The comparison of exact and approximated NEGF calculations illustrates the physical implications and validity of common approximations and suggests numerically efficient simplifications.
影响因子：
8.6
作者：
Schull, Guillaume;Frederiksen, Thomas;Berndt, Richard
通讯作者：
Berndt, Richard