  In time-dependent density-functional theory, a family of exchange-correlation
kernels, known as long-range-corrected (LRC) kernels, have shown promise in the
calculation of excitonic effects in solids. We perform a systematic assessment
of existing static LRC kernels (empirical LRC, Bootstrap, and
jellium-with-a-gap model) for a range of semiconductors and insulators,
focusing on optical spectra and exciton binding energies. We find that no LRC
kernel is capable of simultaneously producing good optical spectra and
quantitatively accurate exciton binding energies for both semiconductors and
insulators. We propose a simple and universal, empirically scaled Bootstrap
kernel which yields accurate exciton binding energies for all materials under
consideration, with low computational cost.
