  The steady state and phase ordering kinetics in a pure active Borwnian
particle system are studied in recent years. In binary mixture of active and
passive Brownian particles passive particles are used as probe to understand
the properties of active medium. In our present study we study the mixture of
passive and active Brownian particles. Here we aim to understand the steady
state and kinetics of small passive particles in the mixture. In our system,the
passive particles are small in size and large in number, whereas ABPs are large
in size and small in number. The system is studied on a two-dimensional
substrate using overdamp Langevin dynamic simulation. The steady state and
kinetics of passive particles are studied for various size and activity of
active particles. Passive particles are purely athermal in nature and have
dynamics only due to bigger ABPs. For small size ratio and activity the passive
particles remain homogeneous in the system, whereas on increasing size ratio
and activity they form periodic hexagonal close pack (HCP) spanning clusters in
the system. We have also studied the kinetics of growing passive particle
clusters. The mass of the largest cluster shows a much slower growth kinetics
in contrast to conserved growth kinetics in ABP system. Our study provides an
understanding of steady state and kinetics of passive particles in the presence
of bigger active particles. The mixture can be thought of as effect of big
microorganism moving in passive medium.
