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arXiv 1904.02012cond-mat.mtrl-sciphysics.chem-ph
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基于$GW$的分子-金属界面能级排列计算

Accelerating $GW$-Based Energy Level Alignment Calculations for Molecule-Metal Interfaces Using a Substrate Screening Approach

Zhen-Fei Liu, Felipe H. da Jornada, Steven G. Louie, Jeffrey B. Neaton

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摘要：

在分子和金属之间形成的界面处的电子能级排列的物理学通常可以通过\emph{ab initio} $GW$方法准确地捕获。然而，对于典型界面的这种$GW$计算的计算成本是显著的，考虑到它们的大系统尺寸和化学复杂性。在过去，近似的自能校正，如从图像电荷模型与气相分子水平校正一起构建的那些，已被用来计算具有良好精度的水平对齐。然而，这些方法往往忽略了极化率的动力学效应，并需要定义一个图像平面。在这项工作中，我们提出了一个新的近似，使更有效的$GW$质量计算的接口，在那里我们大大简化了非相互作用的极化率，一个主要的瓶颈，大型异构系统的计算。这是通过首先计算界面的每个单独组分的非相互作用极化率来实现的，例如，分子和金属，而不使用大的超晶胞;然后使用折叠和空间截断技术来有效地组合这些量。总的来说，这种方法显著降低了传统的水平对准的$GW$计算的计算成本，而不牺牲精度。此外，这种方法捕捉动态和非局部极化效应，而不需要调用一个经典的图像电荷表达式或定义一个图像平面。我们证明了我们的方法，通过考虑一个模型系统的苯在相对较低的覆盖率在铝（111）表面。尽管该方法是为此类接口开发的，但它可以很容易地扩展到其他异构接口。

英文摘要：

The physics of electronic energy level alignment at interfaces formed between molecules and metals can in general be accurately captured by the \emph{ab initio} $GW$ approach. However, the computational cost of such $GW$ calculations for typical interfaces is significant, given their large system size and chemical complexity. In the past, approximate self-energy corrections, such as those constructed from image-charge models together with gas-phase molecular level corrections, have been used to compute level alignment with good accuracy. However, these approaches often neglect dynamical effects of the polarizability and require the definition of an image plane. In this work, we propose a new approximation to enable more efficient $GW$-quality calculations of interfaces, where we greatly simplify the calculation of the non-interacting polarizability, a primary bottleneck for large heterogeneous systems. This is achieved by first computing the non-interacting polarizability of each individual component of the interface, e.g., the molecule and the metal, without the use of large supercells; and then using folding and spatial truncation techniques to efficiently combine these quantities. Overall this approach significantly reduces the computational cost for conventional $GW$ calculations of level alignment without sacrificing the accuracy. Moreover, this approach captures both dynamical and nonlocal polarization effects without the need to invoke a classical image-charge expression or to define an image plane. We demonstrate our approach by considering a model system of benzene at relatively low coverage on aluminum (111) surface. Although developed for such interfaces, the method can be readily extended to other heterogeneous interfaces.

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