  We study one-dimensional hardcore lattice gases, with nearest-neighbor
interactions, in the presence of an external potential barrier, that moves on
the periodic lattice with a constant speed. We investigate how the nature of
the interaction (attractive or repulsive) affects particle transport and
determine, using numerical simulations and mean-field calculations, the
conditions for an optimum transport in the system. Physically, the particle
current induced by the time-dependent potential is opposed by a diffusive
current generated by the density inhomogeneity (a traveling wave) built up in
the system, resulting in a current reversal, that crucially depends on the
speed of the barrier and particle-number density. Indeed the presence of
nearest-neighbor interaction has a significant impact on the current: Repulsive
interaction enhances the current, whereas attractive interaction suppresses it
considerably. Quite remarkably, when the number density is low, the current
increases with the strength of the repulsive interaction and the maximum
current is obtained for the strongest possible repulsion strength, i.e., for
the nearest-neighbor exclusion. However, at high density, very strong repulsion
makes particle movement difficult in an overcrowded environment and, in that
case, the maximal current is achieved for weaker repulsive interaction
strength.
