Low-cost alternatives to the Bethe-Salpeter equation: Towards simple hybrid functionals for excitonic effects in solids
Low-cost alternatives to the Bethe-Salpeter equation: Towards simple hybrid functionals for excitonic effects in solids
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DOI：
10.1103/physrevresearch.2.013091
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Jiuyu Sun;Jinlong Yang;C. Ullrich
中科院分区：
文献类型：
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作者：
Jiuyu Sun;Jinlong Yang;C. Ullrich
Bethe-Salpeter方程（BSE）是固体中光学激发（包括激子效应）的标准计算方法。在本文中，我们探索了通过简化介质屏蔽库仑相互作用来降低BSE计算成本的方法：我们不是从第一性原理计算介电函数，而是用动量依赖模型介电函数或仅用单个参数代替它。结合半局部交换相关核，这在广义时变密度泛函理论中定义了固体的混合泛函的另一类。我们对这些简化方法进行了系统的评估，发现它们得到的半导体和宽间隙绝缘体的光吸收光谱和激子结合能与标准BSE和实验结果非常吻合。我们还介绍了钙钛矿材料的应用，这是一个更复杂系统的例子。
The Bethe-Salpeter equation (BSE) is the standard computational method for optical excitations in solids, including excitonic effects. In this paper we explore ways to reduce the computational cost of the BSE by simplifying the dielectrically screened Coulomb interaction: Instead of calculating the dielectric function from first principles, we replace it by a momentum-dependent model dielectric function or just by a single parameter. Combined with a semilocal exchange-correlation kernel, this defines an alternative class of hybrid functionals for solids within generalized time-dependent density-functional theory. We perform a systematic assessment of these simplified approaches and find that they yield optical absorption spectra and exciton binding energies of semiconductors and wide-gap insulators in close agreement with the standard BSE and with experiment. We also present applications to the perovskite materialas an example of a more complex system.