Low-cost alternatives to the Bethe-Salpeter equation: Towards simple hybrid functionals for excitonic effects in solids

Abstract

This paper shows that the Bethe-Salpeter equation for optical excitations in solids can be considerably simplified without major loss of accuracy, leading to a significant computational speedup for complex materials such as perovskites. A new hybrid functional within time-dependent density-functional theory is proposed, which is well suited to describe excitonic effects in a broad range of semiconductors and insulators.