  The Lees-Edwards boundary condition (LEbc) was first developed by Lees and
Edwards in 1970s. The current implementation of LEbc in the ESPResSo++ MD
software package provides a new possibility in simulating molecular or coarse
grained systems under such non-equilibrium conditions, namely by introducing a
shear flow which has potential applications in high-speed fluids, thermoplastic
and other non-equilibrium processes etc. Using the LEbc code, shear flow
simulations were carried out in model systems such as the Lennard-Jones fluids
and the Kremer-Grest polymer melts. Some important physical properties and
phenomena, including the linear profiles of shear velocities, non-layered
density distribution and shear thinning, are successfully reproduced or
captured. Results also show in good agreement with those from the previous
literature even with unphysical simulation conditions, which on the other side
gives a solid validation to our implementation of LEbc. Regarding the high
performance computing (HPC) environments, we considered in depth and paid
efforts on the parallelization of the LEbc code in ESPResSo++. By this, a
modified scheme for data communication has been introduced within the framework
of the domain decomposition. The benchmarks show a linear and good scaling for
simulations which are parallelized up to 1024 processors in supercomputer
systems.
