  Molecular dynamics (MD) simulations represent a powerful investigation tool
in the field of soft matter. By using shear flows, one can probe the bulk
rheology of complex fluids, also beyond the linear response regime, in a way
that imitates laboratory experiments. One solution to impose a shear flow in
particle-based simulations is the Lees-Edwards technique which ensures that
particles experience shear by imposing rules for motion and interactions across
the boundary in the direction of the shear plane. Despite their presentation in
1972, a readily available public implementation of Lees-Edwards boundary
conditions has been missing from MD simulation codes. In this article, we
present our implementation of the Lees-Edwards technique and discuss the
relevant technical choices. We used ESPResSo, the extensible simulation package
for research on soft matter, for molecular dynamics simulations which can be
used as a reference for other implementers. We illustrate our implementation
using bulk dissipative particle dynamics fluids, compare different viscosity
measurement techniques, and observe the anomalous diffusion in our samples
during continuous and oscillatory shear, in good comparison to theoretical
estimates.
