Liu Zhen-Fei
Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
J Chem Phys. 2020 Feb 7;152(5):054103. doi: 10.1063/1.5140972.
Molecule-metal interfaces have a broad range of applications in nanoscale materials science. Accurate characterization of their electronic structures from first-principles is key in understanding material and device properties. The GW approach within many-body perturbation theory is the state-of-the-art and can in principle yield accurate quasiparticle energy levels and interfacial level alignments that are in quantitative agreement with experiments. However, the interfaces are large heterogeneous systems that are currently challenging for first-principles GW calculations. In this work, we develop a GW-based dielectric embedding approach for molecule-metal interfaces, significantly reducing the computational cost of direct GW without sacrificing the accuracy. To be specific, we perform explicit GW calculations only in the simulation cell of the molecular adsorbate, in which the dielectric effect of the metallic substrate is embedded. This is made possible via a real-space truncation of the substrate polarizability and the use of the interface plasma frequency in the adsorbate GW calculation. Here, we focus on the level alignment at weakly coupled molecule-metal interfaces, i.e., the energy difference between a molecular frontier orbital resonance and the substrate Fermi level. We demonstrate our method and assess a few GW-based approximations using two well-studied systems, benzene adsorbed on the Al (111) and on the graphite (0001) surfaces.
分子 - 金属界面在纳米尺度材料科学中有着广泛的应用。从第一性原理准确表征其电子结构是理解材料和器件性能的关键。多体微扰理论中的GW方法是目前的先进方法，原则上可以产生与实验定量一致的精确准粒子能级和界面能级排列。然而，这些界面是大型非均匀系统，目前对于第一性原理GW计算具有挑战性。在这项工作中，我们为分子 - 金属界面开发了一种基于GW的介电嵌入方法，在不牺牲准确性的情况下显著降低了直接GW的计算成本。具体而言，我们仅在分子吸附质的模拟单元中进行显式GW计算，其中嵌入了金属基底的介电效应。这通过对基底极化率进行实空间截断以及在吸附质GW计算中使用界面等离子体频率得以实现。在这里，我们关注弱耦合分子 - 金属界面处的能级排列，即分子前沿轨道共振与基底费米能级之间的能量差。我们使用两个经过充分研究的系统，即吸附在Al(111)和石墨(0001)表面上的苯，来展示我们的方法并评估一些基于GW的近似方法。
