  The detection of GW170817 and the accompanying electromagnetic counterpart,
AT2017gfo, have provided an important set of observational constraints for
theoretical models of neutron star mergers, nucleosynthesis, and radiative
transfer for kilonovae. We apply the 3D Monte Carlo radiative transfer code
ARTIS to produce synthetic light curves of the dynamical ejecta from a neutron
star merger, which has been modelled with 3D smooth-particle hydrodynamics
(SPH) and included neutrino interactions. Nucleosynthesis calculations provide
the energy released from radioactive decays of r-process nuclei, and radiation
transport is performed using grey opacities given as functions of the electron
fraction. We present line-of-sight dependent bolometric light curves, and find
the emission along polar lines of sight to be up to a factor of ~2 brighter
than along equatorial lines of sight. Instead of a distinct emission peak, our
bolometric light curve exhibits a monotonic decline, characterised by a
shoulder at the time when the bulk ejecta becomes optically thin. We show
approximate band light curves based on radiation temperatures and compare these
to the observations of AT2017gfo. We find that the rapidly declining
temperatures lead to a blue to red colour evolution similar to that shown by
AT2017gfo. We also investigate the impact of an additional, spherically
symmetric secular ejecta component, and we find that the early light curve
remains nearly unaffected, while after about 1 day the emission is strongly
enhanced and dominated by the secular ejecta, leading to the shift of the
shoulder from 1-2 to 6-10 days.
