Accurate solid-state band gaps via screened hybrid electronic structure calculations.

The band energy differences of solids calculated with screened hybrid density functionals, such as the functional of Heyd-Scuseria-Ernzerhof (HSE), reproduce experimental band gaps with a high degree of accuracy. This unexpected result is here rationalized by observing that band energy differences obtained from generalized Kohn-Sham calculations with screened (short-range) Hartree-Fock-type exchange approach the excitation energies obtained via time-dependent density functional calculations with the corresponding unscreened functional. The latter are expected to be the accurate predictions of the experimental optical absorption spectra.