Role of trapping and crowding as sources of negative differential mobility

TL;DR

This paper investigates how trapping and crowding influence negative differential mobility, emphasizing that crowding alone does not necessarily cause it and that microscopic jump rates significantly affect particle mobility.

Contribution

The study clarifies the roles of trapping and crowding in negative differential mobility and highlights the importance of microscopic jump rates in modeling particle dynamics.

Findings

Crowding does not necessarily induce negative differential mobility.

Trapping enhanced by force is key to non-monotonous drift velocity.

Microscopic jump rates critically influence mobility behavior.

Abstract

Increasing the crowding in an environment does not necessarily trigger negative differential mobility of strongly pushed particles. Moreover, the choice of the model, in particular the kind of microscopic jump rates, may be very relevant in determining the mobility. We support these points via simple examples and we therefore address recent claims saying that crowding in an environment is likely to promote negative differential mobility. Trapping of tagged particles enhanced by increasing the force remains the mechanism determining a drift velocity not monotonous in the driving force.