Double k-Grid Method for Solving the Bethe-Salpeter Equation via Lanczos Approaches.
Double k-Grid Method for Solving the Bethe-Salpeter Equation via Lanczos Approaches.
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DOI：
10.3389/fchem.2021.763946
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发表时间：
2021
影响因子：
5.5
通讯作者：
Grüning M
中科院分区：
文献类型：
--
作者：
Alliati IM;Sangalli D;Grüning M
布里渊区k点采样网格尺寸的收敛性是用Bethe-Salpeter方程（BSE）计算周期晶体光谱的主要瓶颈。我们解决这个挑战，提出了一个双网格的方法k-采样兼容的有效的Lanczos为基础的Haydock迭代解决方案。我们的方法依赖于驱动计算成本的粗k网格，而密集的k网格负责捕获激子效应，尽管是以近似的方式。重要的是，由于我们的方法简单，精细的k网格需要最小的额外计算，这也使得后者易于实现。我们进行了测试体硅，体砷化镓和单层二硫化钼，所有这些产生的光谱与其他地方报道的数据吻合得很好。该框架具有使得能够计算半导体系统中的光谱的潜力，其中单独的Haydock方案的效率不足以实现BSE的计算上易处理的解决方案，例如，具有非常严格的k采样要求以实现收敛的大规模系统。
Convergence with respect to the size of the k-points sampling grid of the Brillouin zone is the main bottleneck in the calculation of optical spectra of periodic crystals via the Bethe-Salpeter equation (BSE). We tackle this challenge by proposing a double grid approach to k-sampling compatible with the effective Lanczos-based Haydock iterative solution. Our method relies on a coarse k-grid that drives the computational cost, while a dense k-grid is responsible for capturing excitonic effects, albeit in an approximated way. Importantly, the fine k-grid requires minimal extra computation due to the simplicity of our approach, which also makes the latter straightforward to implement. We performed tests on bulk Si, bulk GaAs and monolayer MoS2, all of which produced spectra in good agreement with data reported elsewhere. This framework has the potential of enabling the calculation of optical spectra in semiconducting systems where the efficiency of the Haydock scheme alone is not enough to achieve a computationally tractable solution of the BSE, e.g., large-scale systems with very stringent k-sampling requirements for achieving convergence.