论文标题
来自时间依赖性密度功能理论的2D单层的光谱
Optical spectra of 2D monolayers from time-dependent density functional theory
论文作者
论文摘要
二维（2D）周期系统的光谱为时间依赖性密度功能理论（TDDFT）提供了挑战，因为这些材料中具有较大的兴奋性效应。在这项工作中，我们探讨了如何准确地描述这些光谱在纯的Kohn-Sham时间依赖性密度功能框架中，即需要一个框架，在该框架中，需要校正Kohn-Sham Sag的框架，即Kohn-Sham密度功能性理论（例如$ GW $）所必需的。为了实现这一目标，我们为3D系统的光谱[Cavo，Berger，Romaniello，phys提供了一种最新的方法。 Rev. B 101，115109（2020）]到2D系统。我们的方法取决于TDDFT的交换相关核与地面密度功能功能理论的衍生性不连续性之间的联系，该理论保证了正确的准粒子间隙，以及对极化功能的概括[Berger，phys。 Rev. Lett。，115，137402（2015）]，其中描述了激子效应。我们将方法应用于两个典型的2D单层，$ h $ bn和mos $ _2 $。我们发现，我们的协议对$ H $ bn的光谱进行了定性的良好描述，而MOS $ _2 $需要改进来描述激子峰的强度。
The optical spectra of two-dimensional (2D) periodic systems provide a challenge for time-dependent density-functional theory (TDDFT) because of the large excitonic effects in these materials. In this work we explore how accurately these spectra can be described within a pure Kohn-Sham time-dependent density-functional framework, i.e., a framework in which no theory beyond Kohn-Sham density-functional theory, such as $GW$, is required to correct the Kohn-Sham gap. To achieve this goal we adapted a recent approach we developed for the optical spectra of 3D systems [Cavo, Berger, Romaniello, Phys. Rev. B 101, 115109 (2020)] to those of 2D systems. Our approach relies on the link between the exchange-correlation kernel of TDDFT and the derivative discontinuity of ground-state density-functional theory, which guarantees a correct quasi-particle gap, and on a generalization of the polarization functional [Berger, Phys. Rev. Lett., 115, 137402 (2015)], which describes the excitonic effects. We applied our approach to two prototypical 2D monolayers, $h$-BN and MoS$_2$. We find that our protocol gives a qualitative good description of the optical spectrum of $h$-BN, whereas improvements are needed for MoS$_2$ to describe the intensity of the excitonic peaks.
