纳米结中的电子关联：GW近似与单杂质Anderson模型数值精确解的比较
Electronic correlation in nanoscale junctions: Comparison of the GW approximation to a numerically exact solution of the single-impurity Anderson model
摘要：
利用单杂质安德森模型分析了纳米级结中电子相关性的影响，例如由单分子形成的结。数值精确的量子蒙特卡罗计算进行映射出的轨道填充，线性响应电导和光谱函数作为库仑相互作用强度和杂质能级位置的函数。这些数值结果形成了一个基准，对近似的，但更广泛适用的方法，包括电子相关运输可以比较。作为一个例子，自洽GW近似已经实现了安德森模型和结果相比，这个基准。对于弱耦合或水平的位置，使杂质是几乎空的或几乎满的，GW近似被发现是准确的。然而，对于中等或强耦合，GW近似不能正确地表示自旋或电荷波动的影响。无论是光谱函数，也不是线性响应电导准确地给出了整个库仑阻塞平台，以及进入混合价态制度。
英文摘要：
The impact of electronic correlation in nanoscale junctions, e.g. formed by single molecules, is analyzed using the single-impurity Anderson model. Numerically exact Quantum Monte Carlo calculations are performed to map out the orbital filling, linear response conductance and spectral function as a function of the Coulomb interaction strength and the impurity level position. These numerical results form a benchmark against which approximate, but more broadly applicable, approaches to include electronic correlation in transport can be compared. As an example, the self consistent GW approximation has been implemented for the Anderson model and the results compared to this benchmark. For weak coupling or for level positions such that the impurity is either nearly empty or nearly full, the GW approximation is found to be accurate. However, for intermediate or strong coupling, the GW approximation does not properly represent the impact of spin or charge fluctuations. Neither the spectral function nor the linear response conductance are accurately given across the Coulomb blockade plateau and well into the mixed valence regimes.
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