Driven lattice gas of dimers coupled to a bulk reservoir

We investigate the nonequilibrium steady state of a one-dimensional
(1D) lattice gas of dimers. The dynamics is described by a totally
asymmetric exclusion process (TASEP) supplemented by attachment and
detachment processes, mimicking chemical equilibrium of the 1D
driven transport with the bulk reservoir. The steady-state phase
diagram and current and density profiles are calculated using both
a refined mean-field theory and extensive stochastic simulations.
As a consequence of the on-off kinetics, a phase coexistence region
arises intervening between low and high density phases such that
the discontinuous transition line of the TASEP splits into two
continuous ones. The results of the mean-field theory and
simulations are found to coincide. We show that the physical
picture obtained in the corresponding lattice gas model with
monomers is robust, in the sense that the phase diagram changes
quantitatively, but the topology remains unaltered. The mechanism
for phase separation is identified as generic for a wide class of
driven 1D lattice gases.