  Silver chloride is a material that has been investigated and used for many
decades. Of particular interest are its optical properties, but only few
fundamental theoretical studies exist. We present first-principles results for
the optical properties of AgCl, obtained using time-dependent density
functional theory and many-body perturbation theory. We show that optical
properties exhibit strong excitonic effects, which are correctly captured only
by solving the Bethe-Salpeter equation starting from quasiparticle
self-consistent GW results. Numerical simulations are made feasible by using a
model screening for the electron-hole interaction in a way that avoids the
calculation of the static dielectric constant. A thorough analysis permits us
to discuss localization in bright and dark excitons of silver chloride.
