  We discuss an active phase field crystal (PFC) model that describes a mixture
of active and passive particles. First, a microscopic derivation from dynamical
density functional theory (DDFT) is presented that includes a systematic
treatment of the relevant orientational degrees of freedom. Of particular
interest is the construction of the nonlinear and coupling terms. This allows
for interesting insights into the microscopic justification of phenomenological
constructions used in PFC models for active particles and mixtures, the
approximations required for obtaining them, and possible generalizations.
Second, the derived model is investigated using linear stability analysis and
nonlinear methods. It is found that the model allows for a rich nonlinear
behavior with states ranging from steady periodic and localized states to
various time-periodic states. The latter include standing, traveling, and
modulated waves corresponding to spatially periodic and localized traveling,
wiggling, and alternating peak patterns and their combinations.
