Dielectrically screened hybrid functionals for optical spectra in solids: an alternative to the Bethe-Salpeter equation

The Bethe-Salpeter equation (BSE) is the standard computational method for optical excitations in solids, including excitonic effects. We show that time-dependent density-functional theory is a promising alternative to the BSE, using simple global hybrid functionals where the admixture of nonlocal exchange is controlled by the dielectric constant. Optical absorption spectra are presented for semiconductors and wide-gap insulators, as well as several types of inorganic perovskites. The hybrid approach produces excellent agreement with the BSE while reducing the computational cost significantly.