  We present a screened exact-exchange (SXX) method for the efficient and
accurate calculation of the optical properties of solids, where the screening
is achieved through the zero-wavevector limit of the inverse dielectric
function. The SXX approach can be viewed as a simplification of the
Bethe-Salpeter equation (BSE) or, in the context of time-dependent
density-functional theory, as a first step towards a new class of hybrid
functionals for the optical properties of solids. SXX performs well for bound
excitons and continuum spectra in both small-gap semiconductors and large-gap
insulators, with a computational cost much lower than that of the BSE.
