The optical spectrum of the hydrated (aqueous) electron, e-aq, is the primary observable
by means of which this species is detected, monitored, and studied. In theoretical
calculations, this spectrum has most often been simulated using one-electron mod-
els. Here, we present ab initio simulations of that spectrum in both bulk water and,
for the first time, at the water/vapor interface, using density functional theory and
time-dependent variant. Our results indicate that this approach provides a reliable
description, and quantitative agreement with the experimental spectrum for the bulk
species is obtained using a "tuned" long-range corrected functional. The spectrum of
the interfacial electron is found to be very similar to the bulk spectrum.