| A particle driven by an external force in a molecular crowding environment - a quiescent bath of other particles - makes their spatial distribution inhomogeneous. The bath particles accumulate in front of the biased particle (BP) and are depleted behind, such that a BP travels together with the inhomogeneity it creates. A natural question is what will happen with two BPs when they appear sufficiently close to each other such that the inhomogeneities around each of them start to interfere? In quest for the answer we examine here, via extensive Monte Carlo simulations, the dynamics of two BPs in a quiescent lattice gas of bath particles. We observe that, surprisingly, for sufficiently dense medium both BPs spend most of the time together which signifies that the interference of the microstructural inhomogeneities results in effectively attractive interactions between them. Such statistical pairing of BPs allows to minimize the size of the inhomogeneity and thus, to reduce the frictional drag force exerted on the BPs by the medium. These interactions, of course, are absent in absence of the external force and/or of the quiescent bath. |
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