  We explore the changes in static structure of a two-dimensional system of
active Brownian particles (ABP) with hard-disk interactions, using event-driven
Brownian dynamics simulations. In particular, the effect of the self-propulsion
velocity and the rotational diffusivity on the orientationally-averaged fluid
structure factor is discussed. Typically activity increases structural ordering
and generates a structure factor peak at zero wave vector which is a precursor
of motility-induced phase separation. Our results provide reference data to
test future statistical theories for the fluid structure of active Brownian
systems.
