  We explore crystallisation and polymorph selection in active Brownian
particles with numerical simulation. In agreement with previous work [Wysocki
$\textit{et al.}$ $\textit{Europhys. Lett.}$, $\textbf{105}$ 48004 (2014)], we
find that crystallisation is suppressed by activity and occurs at higher
densities with increasing $P\'{e}clet$ number ($Pe$). While the nucleation rate
decreases with increasing activity, the crystal growth rate increases due to
the accelerated dynamics in the melt. As a result of this competition we
observe the transition from a nucleation and growth regime at high $Pe$ to
"spinodal nucleation" at low $Pe$. Unlike the case of passive hard spheres,
where preference for FCC over HCP polymorphs is weak, activity causes the
annealing of HCP stacking faults, thus strongly favouring the FCC symmetry at
high $Pe$. When freezing occurs more slowly, in the nucleation and growth
regime, this tendency is much reduced and we see a trend towards the passive
case of little preference for either polymorph.
