分子接触中非平衡量子输运的守恒GW方案
Conserving GW scheme for nonequilibrium quantum transport in molecular contacts
摘要：
我们给出了一个详细的介绍，我们最近的计划，包括在分子输运计算中使用的GW近似的非平衡Keldysh形式主义的相关效应。我们将GW的自能限制在中心区域，并采用密度泛函理论（DFT）对其进行了描述。一个最小的最大本地化的Wannier函数的基础上应用在中央GW区域和铅。使用一个保守的，即完全自洽的，GW自能的重要性，证明了分析和数值例子。我们引入了一个有效的自旋相关的相互作用，自动减少自相互作用的错误的所有订单的相互作用。该计划适用于安德森模型在平衡和出。在零温度下的平衡，我们发现GW描述的近藤共振相当好的中间相互作用强度。平衡，我们证明了一杆G 0 W 0近似可以产生严重的错误，特别是在高偏置。最后，我们考虑一个苯分子之间的无特征的线索。据发现，分子的HOMO-LUMO间隙计算GW显着减少耦合到引线的增加，反映了更有效的屏蔽在强耦合结。对于结的IV特性，我们发现HF和G 0 W 0 [G_HF]产生的结果比DFT和G 0 W 0 [G_DFT]更接近GW。这是解释在自相互作用的影响和寿命减少，由于电子-电子相互作用。
英文摘要：
We give a detailed presentation of our recent scheme to include correlation effects in molecular transport calculations using the GW approximation within the non-equilibrium Keldysh formalism. We restrict the GW self-energy to the central region, and describe the leads by density functional theory (DFT). A minimal basis of maximally localized Wannier functions is applied both in the central GW region and the leads. The importance of using a conserving, i.e. fully self-consistent, GW self-energy is demonstrated both analytically and by numerical examples. We introduce an effective spin-dependent interaction which automatically reduces self-interaction errors to all orders in the interaction. The scheme is applied to the Anderson model in- and out of equilibrium. In equilibrium at zero temperature we find that GW describes the Kondo resonance fairly well for intermediate interaction strengths. Out of equilibrium we demonstrate that the one-shot G0W0 approximation can produce severe errors, in particular at high bias. Finally, we consider a benzene molecule between featureless leads. It is found that the molecule's HOMO-LUMO gap as calculated in GW is significantly reduced as the coupling to the leads is increased, reflecting the more efficient screening in the strongly coupled junction. For the IV characteristics of the junction we find that HF and G0W0[G_HF] yield results closer to GW than does DFT and G0W0[G_DFT]. This is explained in terms of self-interaction effects and life-time reduction due to electron-electron interactions.
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