Double k-Grid Method for Solving the Bethe-Salpeter Equation via Lanczos Approaches.

ABSTRACT: 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

SUBMITTER: Alliati IM 

PROVIDER: S-EPMC8811451 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature