  Swarms of self-propelled particles exhibit complex behavior that can arise
from simple models, with large changes in swarm behavior resulting from small
changes in model parameters. We investigate the steady-state swarms formed by
self-propelled Morse particles in three dimensions using molecular dynamics
simulations optimized for GPUs. We find a variety of swarms of different
overall shape assemble spontaneously and that for certain Morse potential
parameters coexisting structures are observed. We report a rich "phase diagram"
of athermal swarm structures observed across a broad range of interaction
parameters. Unlike the structures formed in equilibrium self-assembly, we find
that the probability of forming a self-propelled swarm can be biased by the
choice of initial conditions. We investigate how thermal noise influences swarm
formation and demonstrate ways it can be exploited to reconfigure one swarm
into another. Our findings validate and extend previous observations of
self-propelled Morse swarms and highlight open questions for predictive
theories of nonequilibrium self-assembly.
