Importance of nonuniform Brillouin zone sampling for ab initio Bethe-Salpeter equation calculations of exciton binding energies in crystalline solids
Importance of nonuniform Brillouin zone sampling for ab initio Bethe-Salpeter equation calculations of exciton binding energies in crystalline solids
复制标题
非均匀布里渊区采样对于结晶固体中激子结合能的从头算 Bethe-Salpeter 方程计算的重要性
DOI：
10.1103/physrevb.108.235117
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发表时间：
2023
影响因子：
3.7
通讯作者：
Alvertis A
中科院分区：
文献类型：
--
作者：
Alvertis A
激子普遍存在于半导体和绝缘体中，其结合能对于光电应用至关重要。扩展系统中激子第一性原理计算的最先进方法是从头开始的 Bethe-Salpeter 方程 (BSE) 方法，该方法需要对倒易空间进行精细采样才能准确解析固态激子特性。在这里，我们表明，对于一系列半导体和绝缘体，常用的布里渊区均匀采样方法可能会导致激子结合能欠收敛，因为需要不切实际的网格尺寸才能实现足够的收敛。我们进一步表明，布里渊区的非均匀采样，集中在激子波函数所在的倒易空间区域，可以在给定的理论水平上实现激子结合能的有效快速数值收敛。我们提出了一种定义明确的收敛过程，该过程可以以相对较低的计算成本进行，并且在某些情况下导致将先前的最佳理论估计修正近 2 倍，从质上改变了预测的激子物理。这些结果要求采用非均匀采样方法进行从头 BSE 计算，并重新审视之前计算的许多系统的激子结合能值。
Excitons are prevalent in semiconductors and insulators, and their binding energies are critical for optoelectronic applications. The state-of-the-art method for first-principles calculations of excitons in extended systems is theab initio-Bethe-Salpeter equation (BSE) approach, which can require a fine sampling of reciprocal space to accurately resolve solid-state exciton properties. Here we show, for a range of semiconductors and insulators, that the commonly employed approach of uniformly sampling the Brillouin zone can lead to underconverged exciton binding energies, as impractical grid sizes are required to achieve adequate convergence. We further show that nonuniform sampling of the Brillouin zone, focused on the region of reciprocal space where the exciton wave function resides, enables efficient rapid numerical convergence of exciton binding energies at a given level of theory. We propose a well-defined convergence procedure, which can be carried out at relatively low computational cost and which in some cases leads to a correction of previous best theoretical estimates by almost a factor of 2, qualitatively changing the predicted exciton physics. These results call for the adoption of nonuniform sampling methods forab initio-BSE calculations and for revisiting previously computed values for exciton binding energies of many systems.