  We present a method to compute the photoionization spectra of atoms and
molecules in linear response time-dependent density functional theory. The
electronic orbital variations corresponding to ionized electrons are expanded
on a basis set of delocalized functions obtained as the solution of the
inhomogeneous Helmholtz equation with gaussian basis set functions as
right-hand side. The resulting scheme is able to reproduce photoionization
spectra without any need for artificial regularization or localization. We
demonstrate that it is able to produce accurate spectra for semilocal
exchange-correlation functionals even using relatively small standard gaussian
basis sets.
